Date: Wed, 10 Jan 2024 16:57:08 +0000 From: Stanislav Silnicki <stanislav.silnicki@mailgate.us> To: FreeBSD ARM List <freebsd-arm@freebsd.org> Subject: Re: STM32MP157 Message-ID: <686297325f0d8.847517e9afdee@mailgate.us> References: <4d6bf0126f4fb.c24cc5f2fa47c@mailgate.us> <cade2176971ebe57c4cf952a633e12d5@ohdata.se> <00cab7929791c.8af55c0bd1d5f@mailgate.us> <5d65957f4c04a4bec7ae6ef5469b149c@ohdata.se> <d12e3b1a90216.8e6290090dd15@mailgate.us> <0dab0fc75864.77e1118ea80bb@mailgate.us> <5aa7e3eff95c.2102a80bb1a3b@mailgate.us> <0926803a4f0a.17799edcfe428@mailgate.us> <19de1a006e313.760d63ffe37aa@mailgate.us> <41EBB5DE-EB46-435A-98FC-9017A2CE3B10@mit.edu> <efc9993b489d1.5c9a553874833@mailgate.us> <689d44174e0f9.1733c7a78ebda@mailgate.us>
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------sinikael-?=_1-17049058292700.7558567376711265 Content-Type: text/plain; format=flowed Content-Transfer-Encoding: 7bit WIP status: So far implemented: - u-boot config + DTS with SPL (only secure mode). A port is prepared and compiled, while pending dev. testing. - uart: EARLY_PRINTF, low-level driver interface (full console). high level methods are pending implementation, though seem trivial. - SMP: second core is started Pending: - sd/mmc (a must) - rtc (seems trivial) - net if driver (optional?) Couple questions to community: 1. Shall I consider any other parts to port to be able to pass phabricator & review? 2. My current board with STM32MP1 (Karo's Qbase4 + QSMP1570 module) does not have sd card connector soldered. May I consider a description in port's README of how to solder an SD Card to be able to boot from one? There is also an option to describe how to flash onboard 4Gb emmc chip. A special question about 32bit systems discontinuty: is it mainly a warning for i386 or there is a real plan to abandon armv7? Stan Stanislav Silnicki wrote: Reading TCMTR shows 0x0, so is looks like TCM is not implemented in my case... Stanislav Silnicki wrote: if you mean SRAM, stm32mp1 has some @ 0x20000000. In my current setup with ftfp boot, it is used to load SPL+uboot, then, kernel is loaded into default kernel space @ 0xc0000000, where DRAM starts. At the _start kernel's entry sp is something about 0xdd....., so it uses DRMA as well. Where can I find traces of TCM usage? John F Carr wrote: Are you using a chip where some memory can be mapped as TCM or cache? Trying to use the memory both ways could cause problems. <block quote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> On Nov 18, 2023, at 19:46, Stanislav Silnicki <stanislav.silnicki@mailgate.us> wrote: The root cause of zeroed stack in my setup with STM32MP157 seems to be in the TEX remapping registers values, calculated by pmap_set_tex(void). It can be a wrong assumption, as I'm not sure of any hardware (OTP/Security) tunings, that might be in effect.... Blindly copied values for PRRR & NMRR registers from Linux kernel (6.1.28), supplied by STM in their distribution I could avoid the trouble with zeroed stack memory. The hardcoded values are: rg ".equ\s+(PR|NM)RR" arch/arm/mm/* arch/arm/mm/proc-v7-3level.S 110:.equ PRRR, 0xeeaa4400 @ MAIR0 111:.equ NMRR, 0xff000004 @ MAIR1 arch/arm/mm/proc-v7-2level.S 137:.equ PRRR, 0xff0a81a8 138:.equ NMRR, 0x40e040e0 I (wrongly?) assume, 2level is related to the ones, calculated by pmap_set_tex. Narrowing down the inconsistency among values found in Linux kernel and calculated here, I came to the result that the type of inner cache, tuned for first value of tex_classes lut ruins memory: TEX(PRRR_MEM, NMRR_WB_WA, NMRR_WB_WA, 0), /* 0 - ATTR_WB_WA */ - zeroes stack mem on TLB flush TEX(PRRR_MEM, NMRR_WB, NMRR_WB_WA, 0), /* 0 - ATTR_WB_WA */ - zeroes stack mem on TLB flush TEX(PRRR_MEM, NMRR_WT, NMRR_WB_WA, 0), /* 0 - ATTR_WB_WA */ - DOES NOT zeroes stack mem on TLB flush TEX(PRRR_MEM, NMRR_NC, NMRR_WB_WA, 0), /* 0 - ATTR_WB_WA */ - DOES NOT zeroes stack mem on TLB flush Need further investigation.... Any clues? Stan Stanislav Silnicki wrote: STM32MP15x port current progress: ... it took some time to solder down the probe and establish conveniences with remote kernel debug... So far, I need to understand, whither or not I face an expected behavior? It looks like tlb_flush_all_local() (https://github.com/freebsd/freebsd-src/blob/525ecfdad597980ea4cd59238e24c8530dbcd31d/sys/arm/arm/pmap-v6.c#L512C14-L512C14) destroys stack memory, where return address is stored, so when stored lr is poped into pc, it is 0x0.... here is a dump of my debug session around that code: 508 cp15_prrr_set(prrr); (kgdb) i f Stack level 0, frame at 0xc0784598: pc = 0xc0557b44 in pmap_set_tex (/usr/src/sys/arm/arm/pmap-v6.c:508); saved pc = 0xc055254c called by frame at 0xc07847e0 source language c. Arglist at 0xc0784590, args: Locals at 0xc0784590, Previous frame's sp is 0xc0784598 Saved registers: r4 at 0xc0784580, r5 at 0xc0784584, r6 at 0xc0784588, r10 at 0xc078458c, r11 at 0xc0784590, lr at 0xc0784594 (kgdb) x 0xc0784594 0xc0784594: 0xc055254c (kgdb) n stm32mp15x.cpu0 rev 5, partnum c07, arch f, variant 0, implementor 41 stm32mp15x.cpu1 rev 5, partnum c07, arch f, variant 0, implementor 41 target halted in Thumb state due to debug-request, current mode: Supervisor cpsr: 0x600001f3 pc: 0x0000060e MMU: disabled, D-Cache: disabled, I-Cache: enabled 509 cp15_nmrr_set(nmrr); (kgdb) x 0xc0784594 0xc0784594: 0xc055254c (kgdb) n stm32mp15x.cpu0 rev 5, partnum c07, arch f, variant 0, implementor 41 stm32mp15x.cpu1 rev 5, partnum c07, arch f, variant 0, implementor 41 target halted in Thumb state due to debug-request, current mode: Supervisor cpsr: 0x600001f3 pc: 0x0000060e MMU: disabled, D-Cache: disabled, I-Cache: enabled 512 tlb_flush_all_local(); (kgdb) x 0xc0784594 0xc0784594: 0xc055254c (kgdb) si stm32mp15x.cpu0 rev 5, partnum c07, arch f, variant 0, implementor 41 stm32mp15x.cpu1 rev 5, partnum c07, arch f, variant 0, implementor 41 target halted in Thumb state due to debug-request, current mode: Supervisor cpsr: 0x600001f3 pc: 0x0000060e MMU: disabled, D-Cache: disabled, I-Cache: enabled _CP15_TLBIALL () at /usr/src/sys/arm/include/cpu-v6.h:147 147 _WF0(_CP15_TLBIALL, CP15_TLBIALL) /* Invalidate entire unified TLB */ (kgdb) si stm32mp15x.cpu0 rev 5, partnum c07, arch f, variant 0, implementor 41 stm32mp15x.cpu1 rev 5, partnum c07, arch f, variant 0, implementor 41 target halted in Thumb state due to debug-request, current mode: Supervisor cpsr: 0x600001f3 pc: 0x0000060e MMU: disabled, D-Cache: disabled, I-Cache: enabled tlb_flush_all_local () at /usr/src/sys/arm/include/cpu-v6.h:340 340 dsb(); (kgdb) x 0xc0784594 0xc0784594: 0x00000000 (kgdb) si stm32mp15x.cpu0 rev 5, partnum c07, arch f, variant 0, implementor 41 stm32mp15x.cpu1 rev 5, partnum c07, arch f, variant 0, implementor 41 target halted in Thumb state due to debug-request, current mode: Supervisor cpsr: 0x600001f3 pc: 0x0000060e MMU: disabled, D-Cache: disabled, I-Cache: enabled pmap_set_tex () at /usr/src/sys/arm/arm/pmap-v6.c:513 513 } (kgdb) si Polling target stm32mp15x.cm4 failed, trying to reexamine Failed to read memory at 0xe000ed00 Examination failed, GDB will be halted. Polling again in 100ms Program stopped. pmap_set_tex () at /usr/src/sys/arm/arm/pmap-v6.c:513 513 } (kgdb) The address, referenced from error message (0xe000ed00) is mapped by STM's address space to "DDR extension (CA7 only) or Debug" with debug assigned to Cortex-M4 coprocessor. I'm not sure, that it is an unexpected behav. (it is my first attempt to port to armv7), so need an advice. Any? Stan Stanislav Silnicki wrote: my current progress of STM32MP1xx port attempt: Basically, both options to boot ubldr and then kernel in SPL & TF-A modes of u-boot are supported. Initially, when I stated from TF-A options (security supervision from arm's trusted firmware os) I stuck with this line: https://github.com/freebsd/freebsd-src/blob/501bdf3001190686bf55d9d333cb533858c2cf2f/sys/arm/arm/locore-v6.S#L371 control does not seem to reach beyond that point. I tried to enable the led with this assembly, which works anywhere else: /* prepare to use LED @ GPIOA 13*/ ldr r0, =0x50002014 ldr r1, =0xFFFFDFFF ldr r2, [r0] and r2, r1, r2 /* Enable caches. */ mrc CP15_SCTLR(r7) orr r7, #CPU_CONTROL_DC_ENABLE orr r7, #CPU_CONTROL_IC_ENABLE orr r7, #CPU_CONTROL_BPRD_ENABLE mcr CP15_SCTLR(r7) DSB /* turn on GPIO LED */ str r2, [r0] Control passes if I disable data cache ORing instruction, but then hangs on setting of new TTB couple lines below... I thought it was due to security access control from TF-A, but it behaves the same w/o. Any clues or expertise from other platforms are highly appreciated. Stan Stanislav Silnicki wrote: Hello, I need an advice on the intial addresses layout when booting the kernel. As I understand, ubldr is the proper way to boot the kernel. What is the correct address to load it, given that I wand to keep default KERNVIRTADDR (=0xc0000000) intact? The u-boot loads ubldr this way in my current setup: // FreeBSD version of environment env_set("baudrate", "115200"); env_set("console", "ttyS0,115200"); env_set("stderr", "serial"); env_set("stdin", "serial"); env_set("stdout", "serial"); env_set("autostart", "yes"); env_set("loaderdev", "mmc 1"); // fbsd's ubldr treats our second mmc at index 1 env_set("bootcmd", "fatload mmc 2 0xc0000000 ubldr && bootelf"); then ubldr leads the kernel from mmc and passes it the control: Loading kernel... /boot/kernel/kernel text=0x1b4 text=0x5b8530 text=0x17d91c data=0xa4a60 data=0x0+0x20c000 0x4+0x88810+0x4+0xe9d98| Loading configured modules... can't find '/boot/entropy' can't find '/etc/hostid' Using DTB compiled into kernel. Kernel entry at 0xc0400200... Kernel args: (null) Then I could correctly pass the init of MMU and get into translated mode only with setting KERNVIRTADDR = 0xc4000000. It looks like kernel and loader clash somehow. So, just need to understand what is best option to load ubldr to? Will it affect further routines? Stan Stanislav Silnicki wrote: OK, I got the idea! As I realize, there is a minor bug in dtc, which affects compilation of stm's originated DTBs. I think it is best to make a PR into https://github.com/davidchisnall/dtc, which I'm discussing with repo owner already. Please tell me, that I need to post PR into FBSD source tree if it is a shorter way for my fix. My current setup is based upon QBASE1 from Karo-Electronics, but there is no goal to support/debug all peripherals, only a subset, including USB, I2C, SDMMC, DSI (and GPU, if lucky). https://www.karo-electronics.com/fileadmin/download/Datasheets/QSMP-QSBASE1-Evalkit.pdf The vendor (Karo) supports only their Yocto based Linux distro. I spent some time to prepare TF-A & Uboot, capable with booting from SD card (that is more robust approach, as I think). STM does not promote/support non-secure boot approach with SPL, they insist to use TF-A or OPTEE, so it is pretty cumbersome path, I had to pass. I think, it will be easier for me to prepare some sort of README to support customization of uboot for STM's port and dig it somewhere in SRC rather than ; ; ; ; ;try to post PR's in those repos... Not sure, anyway. So far I'm struggling with uart and early_printf... I'm mixing this activity with my current occupation, so I don't expect rapid progress. Thank you for clarifications! I'll try to do my best! Stan Oskar Holmlund wrote: Hi Stanislav, Please resend your message and CC the arm mailing list. It might be interesting for someone in the future ( https://lists.freebsd.org/archives/freebsd-arm/ ) otherwise they all think you stopped working on the STM32 port. You should always keep one terminal up n running % man 9 style :) https://wiki.freebsd.org/Phabricator will give you some information. Its good if you get to know the people active in the ARM area, just keep an eye on the mailinglist and you will notice some names. If you have the opportunity to join any of the conference (eurobsdcon.org, asiabsdcon.org, bsdcan.org) to get to know even more people. Join the IRC, for example on efnet #bsdmips is a good channel for ARM stuff. Start with small changes and you will get feedback. From there the experience will grow and you will get into it all. Correct, the device-tree import is from the Linux kernel and there is no prior work for the STM32MP15 SoCs. I cant find anything about the STM32MP15x in Net or OpenBSD either. Probably because the STM32MP15 is the first(?) application SoC from ST? 1) hum? Do you need that for the reviews? It should be in SRC 2) Target branch is probably main. 3) It depends, if your custom board is opensource and availble around the globe through mouser/farnell/.. I dont see any problem. Otherwise pick the board from ST that you used as a reference when you developed the custom board. For example in my day job we have a custom board built around the octavosystems OSD3358 that can be found in pocketbeagle/beaglebone black wifi. So the code thats goes into the FreeBSD project are all tested on the beaglebone boards. The stuff we need for our custom board like the device tree is keept as local patches in our inhouse build process. //Oskar 2023-10-28 14:25 skrev Stanislav Silnicki: Hi Oskar! > can you point me some guidelines to help myself to fit development process? I'm sure, there is mature dev. culture around FBSD and I'd be happy to make my contribution coherently from the beginning. > So far I'm done with setup of my account at reviews (keys, 2FA, etc.) > As I understand, there is no considerable progress with STM32, although I have noticed, there are some DTS imported into the project. > > Indeed, several major questions: 1. repo url? 2. tagret branch for patches for stm32 hw? 3. is it possible to target custom board from our project, or I have to ensure support for all dev. boards, provided by STM? > Thank you,Stan > Oskar Holmlund wrote: >> 2023-10-27 22:33 skrev Stanislav Silnicki: quote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> >>> Hello! I'm porting onto the subject hardware. So far the progress is modest, while the system boots (without console although...) One of major issues is hardcoded value inside locore-v6.S. Here is my relevant post: >> > https://community.st.com/t5/stm32-mpus-embedded-software/freebsd-port-for-mp157c/td-p/601438 [1] What is the best way to proceed? Patch, vendor kernel build, something else? Stan > Links: ------ >> [1] > > https://community.st.com/t5/stm32-mpus-embedded-software/freebsd-port-for-mp157c/td-p/601438 >> Hi Stan, >> Upload your patch to reviews.freebsd.org >> Love to see your other patches for the STM32MP15x. kquote> >> //Oskar < < > </block ------sinikael-?=_1-17049058292700.7558567376711265 Content-Type: text/html; format=flowed Content-Transfer-Encoding: 7bit <html><head></head><body><div> <meta charset="utf-8"> <div id="compose-body-wrapper" dir="auto"><div dir="auto">WIP status:</div><div dir="auto"><br></div><div dir="auto">So far implemented:</div><div dir="auto">- u-boot config + DTS with SPL (only secure mode). A port is prepared and compiled, while pending dev. testing.</div><div dir="auto">- uart: EARLY_PRINTF, low-level driver interface (full console). high level methods are pending implementation, though seem trivial.</div><div dir="auto">- SMP: second core is started</div><div dir="auto"><br></div><div dir="auto">Pending:</div><div dir="auto">- sd/mmc (a must)</div><div dir="auto">- rtc (seems trivial)</div><div dir="auto">- net if driver (optional?)</div><div dir="auto"><br></div><div dir="auto">Couple questions to community:</div><div dir="auto">1. Shall I consider any other parts to port to be able to pass phabricator & review?</div><div dir="auto" id="tmjah_g_1299">2. My current board with STM32MP1 (Karo's Qbase4 + QSMP1570 module) does not have sd card connector soldered.</div><div dir="auto" id="tmjah_g_1299">May I consider a description in port's README of how to solder an SD Card to be able to boot from one? There is also an option to describe how to flash onboard 4Gb emmc chip.</div><div dir="auto" id="tmjah_g_1299"><br></div><div dir="auto" id="tmjah_g_1299">A special question about 32bit systems discontinuty: is it mainly a warning for i386 or there is a real plan to abandon armv7?</div><div dir="auto" id="tmjah_g_1299"><br></div><div dir="auto" id="tmjah_g_1299">Stan</div><br></div><div class="replyHeader" dir="auto">Stanislav Silnicki wrote:</div><br><br><div><blockquote cite="mid:689d44174e0f9.1733c7a78ebda@mailgate.us" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div> <meta charset="utf-8"> <div> <meta charset="utf-8"> <div id="compose-body-wrapper" dir="auto"><div dir="auto">Reading TCMTR shows 0x0, so is looks like TCM is not implemented in my case...</div><div dir="auto"><br></div></div><div class="replyHeader" dir="auto">Stanislav Silnicki wrote:</div><br><br><div><blockquote cite="mid:efc9993b489d1.5c9a553874833@mailgate.us" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div> <meta charset="utf-8"> <div id="compose-body-wrapper" dir="auto"><div dir="auto"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">if </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">you </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">mean </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">SRAM, </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">stm32mp1 </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">has </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">some @ </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">0x20000000. </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">In </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">my </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">current </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">setup </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">with </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">ftfp </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">boot, </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">it </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">is </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">used </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">to </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">load </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">SPL+</span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">uboot, </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">then, </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">kernel </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">is </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">loaded </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">into </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">default </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">kernel </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">space @ </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">0xc0000000, </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">where </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">DRAM </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">starts. </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">At </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">the </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">_start </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">kernel's </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">entry </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">sp </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">is </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">something </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">about </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">0xdd....., </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">so </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">it </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">uses </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">DRMA </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">as </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">well. </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">Where </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">can </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">I </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">find </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">traces </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">of </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">TCM </span><wbr style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;"><span style="font-family: "Open Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 14px;">usage?</span><br></div><div dir="auto"><br></div></div><div class="replyHeader" dir="auto">John F Carr wrote:</div><br><br><div><blockquote cite="mid:41EBB5DE-EB46-435A-98FC-9017A2CE3B10@mit.edu" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>Are you using a chip where some memory can be mapped as TCM or cache?</div><div>Trying to use the memory both ways could cause problems.</div><div><br></div><br><block<div>quote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div> On Nov 18, 2023, at 19:46, Stanislav Silnicki <stanislav.silnicki@mailgate.us> wrote:</div><div> </div><div> The root cause of zeroed stack in my setup with STM32MP157 seems to be in the TEX remapping registers values, calculated by pmap_set_tex(void). It can be a wrong assumption, as I'm not sure of any hardware (OTP/Security) tunings, that might be in effect....</div><div> </div><div> Blindly copied values for PRRR & NMRR registers from Linux kernel (6.1.28), supplied by STM in their distribution I could avoid the trouble with zeroed stack memory. The hardcoded values are:</div><div> rg ".equ\s+(PR|NM)RR" arch/arm/mm/*</div><div> arch/arm/mm/proc-v7-3level.S</div><div> 110:.equ PRRR, 0xeeaa4400 @ MAIR0</div><div> 111:.equ NMRR, 0xff000004 @ MAIR1</div><div> </div><div> arch/arm/mm/proc-v7-2level.S</div><div> 137:.equ PRRR, 0xff0a81a8</div><div> 138:.equ NMRR, 0x40e040e0</div><div> </div><div> I (wrongly?) assume, 2level is related to the ones, calculated by pmap_set_tex.</div><div> </div><div> Narrowing down the inconsistency among values found in Linux kernel and calculated here, I came to the result that the type of inner cache, tuned for first value of tex_classes lut ruins memory:</div><div> </div><div> TEX(PRRR_MEM, NMRR_WB_WA, NMRR_WB_WA, 0), /* 0 - ATTR_WB_WA */ - zeroes stack mem on TLB flush</div><div> </div><div> TEX(PRRR_MEM, NMRR_WB, NMRR_WB_WA, 0), /* 0 - ATTR_WB_WA */ - zeroes stack mem on TLB flush</div><div> TEX(PRRR_MEM, NMRR_WT, NMRR_WB_WA, 0), /* 0 - ATTR_WB_WA */ - DOES NOT zeroes stack mem on TLB flush</div><div> TEX(PRRR_MEM, NMRR_NC, NMRR_WB_WA, 0), /* 0 - ATTR_WB_WA */ - DOES NOT zeroes stack mem on TLB flush</div><div> </div><div> Need further investigation....</div><div> Any clues?</div><div> </div><div> Stan</div><div> </div><div> Stanislav Silnicki wrote:</div><div> </div><br><blockquote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div> STM32MP15x port current progress:</div><div> </div><div> ... it took some time to solder down the probe and establish conveniences with remote kernel debug...</div><div> </div><div> So far, I need to understand, whither or not I face an expected behavior?</div><div> </div><div> It looks like tlb_flush_all_local() (https://github.com/freebsd/freebsd-src/blob/525ecfdad597980ea4cd59238e24c8530dbcd31d/sys/arm/arm/pmap-v6.c#L512C14-L512C14)</div><div>; destroys stack memory, where return address is stored, so when stored lr is poped into pc, it is 0x0....</div><div> </div><div> here is a dump of my debug session around that code:</div><div> </div><div> 508 cp15_prrr_set(prrr);</div><div> (kgdb) i f</div><div> Stack level 0, frame at 0xc0784598:</div><div> pc = 0xc0557b44 in pmap_set_tex (/usr/src/sys/arm/arm/pmap-v6.c:508); saved pc = 0xc055254c</div><div> called by frame at 0xc07847e0</div><div> source language c.</div><div> Arglist at 0xc0784590, args: </div><div> Locals at 0xc0784590, Previous frame's sp is 0xc0784598</div><div> Saved registers:</div><div> r4 at 0xc0784580, r5 at 0xc0784584, r6 at 0xc0784588, r10 at 0xc078458c, r11 at 0xc0784590, lr at 0xc0784594</div><div> (kgdb) x 0xc0784594</div><div> 0xc0784594: 0xc055254c</div><div> (kgdb) n</div><div> stm32mp15x.cpu0 rev 5, partnum c07, arch f, variant 0, implementor 41</div><div> stm32mp15x.cpu1 rev 5, partnum c07, arch f, variant 0, implementor 41</div><div> target halted in Thumb state due to debug-request, current mode: Supervisor</div><div> cpsr: 0x600001f3 pc: 0x0000060e</div><div> MMU: disabled, D-Cache: disabled, I-Cache: enabled</div><div> 509 cp15_nmrr_set(nmrr);</div><div> (kgdb) x 0xc0784594</div><div> 0xc0784594: 0xc055254c</div><div> (kgdb) n</div><div> stm32mp15x.cpu0 rev 5, partnum c07, arch f, variant 0, implementor 41</div><div> stm32mp15x.cpu1 rev 5, partnum c07, arch f, variant 0, implementor 41</div><div> target halted in Thumb state due to debug-request, current mode: Supervisor</div><div> cpsr: 0x600001f3 pc: 0x0000060e</div><div> MMU: disabled, D-Cache: disabled, I-Cache: enabled</div><div> 512 tlb_flush_all_local();</div><div> (kgdb) x 0xc0784594</div><div> 0xc0784594: 0xc055254c</div><div> (kgdb) si</div><div> stm32mp15x.cpu0 rev 5, partnum c07, arch f, variant 0, implementor 41</div><div> stm32mp15x.cpu1 rev 5, partnum c07, arch f, variant 0, implementor 41</div><div> target halted in Thumb state due to debug-request, current mode: Supervisor</div><div> cpsr: 0x600001f3 pc: 0x0000060e</div><div> MMU: disabled, D-Cache: disabled, I-Cache: enabled</div><div> _CP15_TLBIALL () at /usr/src/sys/arm/include/cpu-v6.h:147</div><div> 147 _WF0(_CP15_TLBIALL, CP15_TLBIALL) /* Invalidate entire unified TLB */</div><div> (kgdb) si</div><div> stm32mp15x.cpu0 rev 5, partnum c07, arch f, variant 0, implementor 41</div><div> stm32mp15x.cpu1 rev 5, partnum c07, arch f, variant 0, implementor 41</div><div> target halted in Thumb state due to debug-request, current mode: Supervisor</div><div> cpsr: 0x600001f3 pc: 0x0000060e</div><div> MMU: disabled, D-Cache: disabled, I-Cache: enabled</div><div> tlb_flush_all_local () at /usr/src/sys/arm/include/cpu-v6.h:340</div><div> 340 dsb();</div><div> (kgdb) x 0xc0784594</div><div> 0xc0784594: 0x00000000</div><div> (kgdb) si</div><div> stm32mp15x.cpu0 rev 5, partnum c07, arch f, variant 0, implementor 41</div><div> stm32mp15x.cpu1 rev 5, partnum c07, arch f, variant 0, implementor 41</div><div> target halted in Thumb state due to debug-request, current mode: Supervisor</div><div> cpsr: 0x600001f3 pc: 0x0000060e</div><div> MMU: disabled, D-Cache: disabled, I-Cache: enabled</div><div> pmap_set_tex () at /usr/src/sys/arm/arm/pmap-v6.c:513</div><div> 513 }</div><div> (kgdb) si</div><div> Polling target stm32mp15x.cm4 failed, trying to reexamine</div><div> Failed to read memory at 0xe000ed00</div><div> Examination failed, GDB will be halted. Polling again in 100ms</div><div> </div><div> Program stopped.</div><div> pmap_set_tex () at /usr/src/sys/arm/arm/pmap-v6.c:513</div><div> 513 }</div><div> (kgdb) </div><div> </div><div> The address, referenced from error message (0xe000ed00) is mapped by STM's address space to "DDR extension (CA7 only) or Debug" with debug assigned to Cortex-M4 coprocessor.</div><div> </div><div> I'm not sure, that it is an unexpected behav. (it is my first attempt to port to armv7), so need an advice.</div><div> Any?</div><div> </div><div> Stan</div><div> </div><div> </div><div> Stanislav Silnicki wrote:</div><div> </div><br><blockquote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div> my current progress of STM32MP1xx port attempt:</div><div> </div><div> Basically, both options to boot ubldr and then kernel in SPL & TF-A modes of u-boot are supported.</div><div> </div><div> Initially, when I stated from TF-A options (security supervision from arm's trusted firmware os) I stuck with </div><div> this line: https://github.com/freebsd/freebsd-src/blob/501bdf3001190686bf55d9d333cb533858c2cf2f/sys/arm/arm/locore-v6.S#L371</div><div>; </div><div> control does not seem to reach beyond that point. I tried to enable the led with this assembly, which works anywhere else:</div><div> </div><div> /* prepare to use LED @ GPIOA 13*/</div><div> ldr r0, =0x50002014</div><div> ldr r1, =0xFFFFDFFF</div><div> ldr r2, [r0]</div><div> and r2, r1, r2</div><div> </div><div> /* Enable caches. */</div><div> mrc CP15_SCTLR(r7)</div><div> orr r7, #CPU_CONTROL_DC_ENABLE</div><div> orr r7, #CPU_CONTROL_IC_ENABLE</div><div> orr r7, #CPU_CONTROL_BPRD_ENABLE</div><div> mcr CP15_SCTLR(r7)</div><div> DSB</div><div> </div><div> /* turn on GPIO LED */</div><div> str r2, [r0]</div><div> </div><div> Control passes if I disable data cache ORing instruction, but then hangs on setting of new TTB couple lines below...</div><div> </div><div> I thought it was due to security access control from TF-A, but it behaves the same w/o.</div><div> </div><div> Any clues or expertise from other platforms are highly appreciated.</div><div> </div><div> Stan</div><div> </div><div> Stanislav Silnicki wrote:</div><div> </div><br><blockquote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div> Hello, I need an advice on the intial addresses layout when booting the kernel.</div><div> </div><div> As I understand, ubldr is the proper way to boot the kernel. </div><div> What is the correct address to load it, given that I wand to keep default KERNVIRTADDR (=0xc0000000) intact?</div><div> </div><div> The u-boot loads ubldr this way in my current setup:</div><div> </div><div> // FreeBSD version of environment</div><div> env_set("baudrate", "115200");</div><div> env_set("console", "ttyS0,115200");</div><div> env_set("stderr", "serial");</div><div> env_set("stdin", "serial");</div><div> env_set("stdout", "serial");</div><div> env_set("autostart", "yes");</div><div> env_set("loaderdev", "mmc 1"); // fbsd's ubldr treats our second mmc at index 1</div><div> env_set("bootcmd", "fatload mmc 2 0xc0000000 ubldr && bootelf");</div><div> </div><div> then ubldr leads the kernel from mmc and passes it the control:</div><div> </div><div> Loading kernel...</div><div> /boot/kernel/kernel text=0x1b4 text=0x5b8530 text=0x17d91c data=0xa4a60 data=0x0+0x20c000 0x4+0x88810+0x4+0xe9d98|</div><div> Loading configured modules...</div><div> can't find '/boot/entropy'</div><div> can't find '/etc/hostid'</div><div> Using DTB compiled into kernel.</div><div> Kernel entry at 0xc0400200...</div><div> Kernel args: (null)</div><div> </div><div> Then I could correctly pass the init of MMU and get into translated mode only with setting KERNVIRTADDR = 0xc4000000. It looks like kernel and loader clash somehow. </div><div> </div><div> So, just need to understand what is best option to load ubldr to? Will it affect further routines?</div><div> </div><div> Stan</div><div> </div><div> </div><div> Stanislav Silnicki wrote:</div><div> </div><div> </div><br><blockquote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div> OK, I got the idea!</div><div> </div><div> As I realize, there is a minor bug in dtc, which affects compilation of stm's originated DTBs. I think it is best to make a PR into https://github.com/davidchisnall/dtc, which I'm discussing with repo owner already. Please tell me, that I need to post PR into FBSD source tree if it is a shorter way for my fix.</div><div> </div><div> My current setup is based upon QBASE1 from Karo-Electronics, but there is no goal to support/debug all peripherals, only a subset, including USB, I2C, SDMMC, DSI (and GPU, if lucky).</div><div> https://www.karo-electronics.com/fileadmin/download/Datasheets/QSMP-QSBASE1-Evalkit.pdf</div><div>; </div><div> The vendor (Karo) supports only their Yocto based Linux distro. I spent some time to prepare TF-A & Uboot, capable with booting from SD card (that is more robust approach, as I think). STM does not promote/support non-secure boot approach with SPL, they insist to use TF-A or OPTEE, so it is pretty cumbersome path, I had to pass. I think, it will be easier for me to prepare some sort of README to support customization of uboot for STM's port and dig it somewhere in SRC rather than ; ; ; ; ;try to post PR's in those repos... Not sure, anyway.</div><div> </div><div> So far I'm struggling with uart and early_printf...</div><div> </div><div> I'm mixing this activity with my current occupation, so I don't expect rapid progress.</div><div> </div><div> Thank you for clarifications! I'll try to do my best!</div><div> </div><div> Stan</div><div> </div><div> Oskar Holmlund wrote:</div><div> </div><div> </div><br><blockquote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div> Hi Stanislav,</div><div> </div><div> Please resend your message and CC the arm mailing list. It might be interesting for someone in the future ( https://lists.freebsd.org/archives/freebsd-arm/ ) otherwise they all think you stopped working on the STM32 port.</div><div> </div><div> You should always keep one terminal up n running % man 9 style :)</div><div> https://wiki.freebsd.org/Phabricator will give you some information.</div><div> Its good if you get to know the people active in the ARM area, just keep an eye on the mailinglist and you will notice some names. If you have the opportunity to join any of the conference (eurobsdcon.org, asiabsdcon.org, bsdcan.org) to get to know even more people.</div><div> Join the IRC, for example on efnet #bsdmips is a good channel for ARM stuff.</div><div> </div><div> Start with small changes and you will get feedback. From there the experience will grow and you will get into it all.</div><div> </div><div> Correct, the device-tree import is from the Linux kernel and there is no prior work for the STM32MP15 SoCs. I cant find anything about the STM32MP15x in Net or OpenBSD either.</div><div> Probably because the STM32MP15 is the first(?) application SoC from ST?</div><div> </div><div> </div><div> 1) hum? Do you need that for the reviews? It should be in SRC</div><div> 2) Target branch is probably main.</div><div> 3) It depends, if your custom board is opensource and availble around the globe through mouser/farnell/.. I dont see any problem. Otherwise pick the board from ST that you used as a reference when you developed the custom board.</div><div> For example in my day job we have a custom board built around the octavosystems OSD3358 that can be found in pocketbeagle/beaglebone black wifi. So the code thats goes into the FreeBSD project are all tested on the beaglebone boards. The stuff we need for our custom board like the device tree is keept as local patches in our inhouse build process.</div><div> </div><div> //Oskar</div><div> </div><div> 2023-10-28 14:25 skrev Stanislav Silnicki:</div><div> </div><br><blockquote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div> Hi Oskar!</div><div> > can you point me some guidelines to help myself to fit development</div><div> process? I'm sure, there is mature dev. culture around FBSD and I'd be</div><div> happy to make my contribution coherently from the beginning.</div><div> > So far I'm done with setup of my account at reviews (keys, 2FA, etc.)</div><div> > As I understand, there is no considerable progress with STM32,</div><div> although I have noticed, there are some DTS imported into the project.</div><div> > > Indeed, several major questions:</div><div> 1. repo url?</div><div> 2. tagret branch for patches for stm32 hw?</div><div> 3. is it possible to target custom board from our project, or I have</div><div> to ensure support for all dev. boards, provided by STM?</div><div> > Thank you,Stan</div><div> > Oskar Holmlund wrote:</div><div> >> 2023-10-27 22:33 skrev Stanislav Silnicki:</div><div> </div><div> quote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"></div><div> >>> Hello!</div><div> </div><br><blockquote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div> </div><br><blockquote class="gmail_quote" type="cite" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div> I'm porting onto the subject hardware. So far the progress is</div><div> modest,</div><div> while the system boots (without console although...)</div><div> One of major issues is hardcoded value inside locore-v6.S. Here</div><div> is my</div><div> relevant post:</div><div> >> > https://community.st.com/t5/stm32-mpus-embedded-software/freebsd-port-for-mp157c/td-p/601438</div><div>; [1]</div><div> What is the best way to proceed? Patch, vendor kernel build,</div><div> something</div><div> else?</div><div> Stan</div><div> </div><div> </div><br></blockquote><div> </div><div> > Links:</div><br></blockquote><div> </div><div> ------</div><div> >> [1] ></div><div> > https://community.st.com/t5/stm32-mpus-embedded-software/freebsd-port-for-mp157c/td-p/601438</div><div>; >> Hi Stan,</div><div> >> Upload your patch to reviews.freebsd.org</div><div> >> Love to see your other patches for the STM32MP15x.</div><div> </div><div> kquote></div><br></blockquote><div> </div><br></blockquote><div> >> //Oskar</div><br></blockquote><br></blockquote><br></blockquote><br></blockquote><br><div> </div><br><br><<div><br><<div><div><div><div><div><div>></div></div></div></div></div></div></div><br></block<div></blockquote></div> </div></blockquote></div> </div> </div></blockquote></div> </div></body></html> ------sinikael-?=_1-17049058292700.7558567376711265--
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