Date: Wed, 29 Jun 2016 16:18:37 -0400 From: Ed Maste <emaste@freebsd.org> To: Tim Kientzle <tim@kientzle.com> Cc: Ian Lepore <ian@freebsd.org>, freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: Booting FreeBSD on BeagleBone Black from microSD by default Message-ID: <CAPyFy2BZJbcOA4VT3A8531zKK58-_iAKSe7RpoxR%2BM3_NJUqDA@mail.gmail.com> In-Reply-To: <87D8B295-950F-4B9D-AF58-0455FC212087@kientzle.com> References: <20160413095534.B48EA406057@ip-64-139-1-69.sjc.megapath.net> <1460560419.52955.23.camel@freebsd.org> <CAPyFy2AHdog0GzLBDQWeg%2B494yWo73gEJzFBPS_v=Nz3YparUA@mail.gmail.com> <87D8B295-950F-4B9D-AF58-0455FC212087@kientzle.com>
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On 29 June 2016 at 00:14, Tim Kientzle <tim@kientzle.com> wrote: > > If I remember correctly, the uboot provided on the stock eMMC image was c= onfigured to see if the SD card had a Linux kernel and load the kernel from= that if it was there. If the SD did not have a Linux kernel, it would fal= l back to eMMC. Yeah. After looking a little more I think the eMMC uboot will read uEnv.txt from the SD card and so it should somehow be possible to chain to a next stage that way, but it does not support UFS and does not have a 'bootelf' command. It is possible to have the eMMC uboot load something from a FAT file system on the SD card and execute it (with something like fatload mmc 1 <addr> <file>; go <addr>) but I don't yet know enough about the boot path here to build a suitable 3rd stage uboot. 1. eMMC SPL 2. eMMC u-boot, loads uEnv.txt from SD 3. SD u-boot 4. SD ubldr 5. kernel > Of course, if you=E2=80=99re willing to hold the boot switch, you can boo= t from SD without changing the eMMC. Right. My goal here would be to be able to produce a SD card image that works out of the box, without using the boot switch or modifying the eMMC in any way. My interest in being able to boot that way comes from a BSDCan talk[1] by Edicarla Andrade and Vin=C3=ADcius Zavam. They have FreeBSD on a BBB controlling a hexapod robot, but they weren't allowed to modify the BBB (provided by their lab) in any way. So they have to press the boot switch every time they power it up. It's a shame that they're doing something interesting with FreeBSD, yet have this minor but annoying boot issue. [1] https://www.bsdcan.org/2016/schedule/events/658.en.html
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