[Linux-exynos] Kernel for Snow XE303C12 board?

Michal Suchanek hramrach at gmail.com
Thu Feb 19 13:07:43 CET 2015


On 18 February 2015 at 17:10, Merlijn Wajer <merlijn at wizzup.org> wrote:
> Hi Michal,
>
>
> On 18/02/15 16:58, Michal Suchanek wrote:
>> Hello,
>>
>> I am trying to boot mainline kernel on the Snow board.
>>
>> I built mainline u-boot and it is loaded by the RO u-boot.
>>
>> I checked out Linus master, built exynos_defconfig and copied the
>> zImage and snow dtb to a partition on the emmc together with a boot
>> script that loads them.
>>
>> The kernel loads and I get a black screen. There are no logs created
>> on the root so init does not run.
>>
>> Is there something special required in the boot script?
>>
>> Maybe I should also include a pause so I can check the dtb actually
>> loaded and there is no typo.
>>
>> Is the exynos_defconfig supposed to work or does it enable broken/not
>> enable required options?
>>
>> Is Linus master supposed to work or do I need some extra patches?
>>
>> Thanks
>>
>> Michal
>
> Current Linus master lacks some important components, so linux-next is
> recommended, for now.

It does not work either. Or something that has next in the name and
can be found at kernel.org, anyway.

>
> My recommendation would be to have a look at this guide:
>
> http://linux-exynos.org/wiki/Samsung_Chromebook_2_XE503C12/Mainline_Linux_Kernel
>
> Note that it is for a slightly different model, but the instructions are
> mostly the same. You just need a different DTS. You can either use the
> dp-integ branch mentioned there, or linux-next from kernel.org.

With dp-integ branch I get display (and keyboard) and then the kernel
locks up waiting for mmc to get detected which never happens. I guess
I can try an USB stick or something.

>
> Typically it's easier to append the dts to the zImage, as done in the

Booting zImage + DT I need no extra step - just cp. Also in case I
used the built kernel on multiple devices I can copy all built dtb
files and just make a symlink on each device which determines what dt
is actually loaded.

> guide. For testing it's also recommended to use nv u-boot rather than
> the "provided" u-boot.

I know no way to rid myself of the "provided" u-boot. AFAIK the board
is set to boot from the onboard flash which is readonly. Supposedly
you can take apart the case and doing so you break the read-protect
connection. However, since there is no documented way of booting from
other media in the case you write a new u-boot to the flash memory and
it does not work it is probably not good idea to try it.

Thanks

Michal



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