On 2/22/25 00:20, Stephen Boyd wrote:
Quoting Caleb Connolly (2025-02-20 17:00:30)
Hi Stephen,
On 2/20/25 20:58, Stephen Boyd wrote:
This series supports running U-Boot as a payload on sc7180 Trogdor
Chromebooks like Lazor or Wormdingler. This is a jumble of different
patches to get to the final goal of booting a Linux distro from the eMMC
on Lazor. I've yet to craft a USB stick with a stock distro but I'll
probably do that next week.
\o/ wow, this is awesome!
Thanks!
you might have some luck booting pmOS, we build depthcharge compatible
images for trogdor
https://images.postmarketos.org/bpo/edge/google-trogdor/
There's also a generic ARM64 EFI image that should work. You may need to
edit the image and remove efi/systemd/drivers/dtbloader.efi from the ESP:
https://images.postmarketos.org/bpo/edge/postmarketos-trailblazer/
Cool thanks for the pointers. I'm loading u-boot as a payload from
depthcharge so that I don't have to remove the write protect on the
flash. It's the altfw boot method.
I tried to boot the Debian ISO from a USB stick but it looks like the
FDT memory node isn't modified when I use u-boot to load the DTB from
the one flashed to the eMMC for the ChromeOS installation. Does the
efi_dt_fixup_protocol run in that case? I've never tried any of this
stuff before so I'm learning while I go.
The /memory node isn't used when booting with EFI, some EFI table is
used instead. I also don't think we use the DT fixup protocol in
mach-snapdragon so that should be a no-op.
I've been using this sort of flow to read the DTB from the FIT image
that chromeos has:
bootflow scan -l
bootflow select 2 # Select the MMC partition for cros bootmethod
bootflow read
bootflow info
fit=$hex_address_for_FDT_from_info_above
imxtract ${fit} fdt-22 ${fdt_addr_r} # fdt-22 matches my board variant
fdt addr ${fdt_addr_r}
load usb 0:2 ${kernel_add_r} /EFI/BOOT/BOOTAA64.EFI
bootefi ${kernel_addr_r} ${fdt_addr_r}
This seems to work to get me to the installation menu but then when I
run installation the kernel doesn't boot and it looks like memory hasn't
been updated per the earlycon info that I see. I'll continue
That's weird indeed.
I think once the FDT is loaded you can just run "bootefi" with no
arguments and it should pick up the USB drive automatically.
If you have some logs I'd be happy to take a look? You can find me
@calebccff in #u-boot-qcom on libera.chat
The first few patches add support for the particular SoC sc7180 used on
Trogdor devices. The next set of patches move the coreboot logic out of
x86 into lib to find the coreboot tables on ARM and stash them in global
data. Then I have a handful of patches to let the coreboot commands and
utilities parse and populate various things like pstore and DT with the
proper data from the coreboot tables. Finally, I add the calls to
coreboot dram parsing code in the snapdragon board so that if coreboot
tables exist we get the memory info from coreboot instead of from an
earlier stage DTB.
I tested the spi driver with the crosec command. The cros bootflow
method almost works, but it seems like chromeos userspace blows up
spectacularly likely because crossystem can't figure out what board it
is running on. I don't really care too much about booting chromeos
userspace here so I'm going to ignore that problem and assume that I can
boot some Linux distro because the eMMC can be read by U-Boot and the
kernel boots.
Guess it's time I finally get my hands on one of these devices :D
I bought a Lazor from eBay for a couple hundred dollars refurbished and
it is basically brand new because the battery was replaced. I want to
get the display working, which I think will require me to port the dsi
and eDP bridge code over even though coreboot would have left everything
largely configured.
Ahh that's annoying, Coreboot doesn't just give you a framebuffer you
can write to?
Kind regards,
--
Caleb (they/them)
