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

[Simon Glass]

Hi Sahaj,

On Mon, 18 Nov 2019 at 00:09, Sahaj Sarup <sahajsarup at gmail.com> wrote:
>
> see in-line...
>
> On Mon, 18 Nov 2019 at 11:16, Simon Glass <sjg at chromium.org> wrote:
> >
> > 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.
>
> Well since the display is blank and the uboot.bin and uboot.fit have
> a correct 0x100 offset, I'll need to wait for my CCD cable to arrive.
> Bob in fact supports ccd:
> https://www.chromium.org/chromium-os/developer-information-for-chrome-os-devices
> Although, i am confused as well since edp is supported, at least in
> the dts files.

Then I suspect it is broken.

>
> >
> > >
> > > - 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.
> >
>
> I know...
>
> > 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.
> >
>
> hmm.. but what about the whole remove the secure screw procedure and
> enable flash writes?

Not needed if you are chain loading, nor with altfw.

You can use it if you build a raw U-Boot, but need a way of recovering it!


> I know vaguely about it.

Regards,
Simon