Date: Sun, 13 Sep 2020 22:30:34 +0100 From: Charles Lecklider <freebsd-stable@lists.invis.net> To: freebsd-stable@freebsd.org Subject: Re: Cannot find announcement that min supported i386 CPU is now i686 Message-ID: <934c2a63-d3b0-dafb-08cf-8572bb313d03@lists.invis.net> In-Reply-To: <6bd2c4f6-5ce1-5a0d-14b3-71831a0443f4@grosbein.net> References: <4460db23-9a29-7972-1b41-74585764a5d7@lists.invis.net> <20200831205136.GA15141@elch.exwg.net> <2986c4ef-6e73-50f9-215e-20e8a9793434@lists.invis.net> <6bd2c4f6-5ce1-5a0d-14b3-71831a0443f4@grosbein.net>
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On 2020-09-01 03:20, Eugene Grosbein wrote: > CPU: Geode(TM) Integrated Processor by AMD PCS (499.91-MHz 586-class CPU) > Origin="AuthenticAMD" Id=0x5a2 Family=0x5 Model=0xa Stepping=2 > Features=0x88a93d<FPU,DE,PSE,TSC,MSR,CX8,SEP,PGE,CMOV,CLFLUSH,MMX> > AMD Features=0xc0400000<MMX+,3DNow!+,3DNow!> > > Of course, its NanoBSD image is built with CPUTYPE=i586 as well as installed packages. You've got CMOV so you'll be fine with 11.4-RELEASE, whereas I don't: CPU: Pentium/P55C (232.68-MHz 586-class CPU) Origin="GenuineIntel" Id=0x543 Family=0x5 Model=0x4 Stepping=3 Features=0x8003bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8,APIC,MMX> Getting 11.4 to work has been a *major* undertaking: Setting CPUTYPE in `make.conf` doesn't set -march for the kernel build tools, so while you can compile world and kernel for i386, you can't actually link it to create a working kernel on a real i586 (I found that out with `/usr/obj` and `/usr/src` mounted over NFS). clang is hypersensitive to command line arguments - if you just fiddle with CFLAGS etc you'll get a duplicate -O2 and/or -march and that results in a kernel/world that can't build itself (ZFS wedges). You must set NO_CPU_CFLAGS= and then each of CFLAGS/CXXFLAGS/COPTFLAGS. Don't try -Os or -Oz (which really do help on a real i586) - ZFS will wedge quickly. 11.4 i386 doesn't honour `vfs.zfs.arc_max` in any meaningful way resulting in one of the `find`s in periodic security wedging ZFS. By ZFS wedging I mean something gets stuck on zio->i having eaten all of kmem (I presume - on the real i586 I expect ~200M in ARC would do that and that's what `top` shows) and that's it for the machine - it doesn't panic, but there's no more disk IO either. This also happens in VirtualBox with 4GB RAM, so it's not a hardware problem. To get 11.4 to behave itself (and it's only been 72 hours so still early days) I've had to set: options KSTACK_PAGES=4 and kern.maxvnode="1024" vm.kmem_size="330M" vm.kmem_size_max="330M" vfs.zfs.arc_max="125M" vfs.zfs.arc_meta_limit="16M" I had to set kmem for 11.3 but not the rest. TL;DR: I'd avoid 11.4 i386 as it doesn't appear to have been tested on i486/i586 at all. Unfortunately I'm not sure 12 is an option yet either - 12.0 chokes on my SiI3124 SATA controllers, and I've yet to compile 12.1 to test (RELEASE has the same problem as 11.4). -C
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