[U-Boot] flashing and testing u-boot on chromebook_bob

Simon Glass sjg at chromium.org
Mon Nov 18 05:46:14 UTC 2019

Hi Sahaj,

On Sun, 17 Nov 2019 at 21:33, Sahaj Sarup <sahajsarup at gmail.com> wrote:
> Hi All,
> I was wondering if you could answer a few questions regarding u-boot
> on Asus CP101 gru/bob ?
> - To test the u-boot image following README.chromium-chainload,
> should I expect output on the display or do I need
> CDD/SuzyQable Cable for serial?

The display should work OK. I don't think that device supports CCD.

> - The CONFIG_SYS_TEXT_BASE is currently 0x00200000 but
> shouldn't it be CONFIG_SYS_TEXT_BASE=0x20000100
> since its supposed to match CONFIG_KERNEL_START
> from /chromiumos/platform/depthcharge/board/gru/defconfig

Yes it is a bit annoying because the in-house bootloader doesn't
support FIT properly. As I recall you have to set it to the exact
address that it appears in the FIT.

> - In order to flash to spi, what's the procedure?

The chain load option doesn't use SPI flash. You actually sign the
image and put it into the kernel partition.

Not much help for you, but there is a new feature on more recent
Chromebooks called 'altfw' (alternative firmware) and if enabled, it
lets you press 1 to boot U-Boot (only in dev mode). It only works on
x86 devices so far and even then the device support is pretty basic if
it boots at all. But the good thing is that you can put things into
the altfw partition in SPI flash and they will boot without affecting
the device.


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