[PATCH] ARM: Distro boot: document the need for fdtfile variable to be set

[Vagrant Cascadian]

On 2020-09-03, Andre Heider wrote:
> On 03/09/2020 18:40, Dennis Gilmore wrote:
>> When testing builds provided in https://github.com/openwrt/openwrt/pull/3360
>> I discovered that fdtfile was not set and as a result the firmware was not
>> functional. So I am documenting what is needed.
>> 
>> Signed-off-by: Dennis Gilmore <dennis at ausil.us>
>> 
>> Cc: Atish Patra <atish.patra at wdc.com>
>> Cc: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
>> Cc: Tom Rini <trini at konsulko.com>
>> Cc: Masahiro Yamada <yamada.masahiro at socionext.com>
>> Cc: Vagrant Cascadian <vagrant at debian.org>
>> Cc: Stephen Warren <swarren at nvidia.com>
>> Cc: Karsten Merker <merker at debian.org>
>> ---
>>   doc/README.distro | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>> 
>> diff --git a/doc/README.distro b/doc/README.distro
>> index 5076bebd18..3eb70aeb14 100644
>> --- a/doc/README.distro
>> +++ b/doc/README.distro
>> @@ -224,6 +224,14 @@ fdt_addr_r:
>>   
>>     A size of 1MB for the FDT/DTB seems reasonable.
>>   
>> +fdtfile:
>> +
>> +  Mandatory. the name of the DTB file for the specific board for instance
>> +  the espressobin v5 board the value is "marvell/armada-3720-espressobin.dtb"
>> +  while on a clearfog pro it is "armada-388-clearfog-pro.dtb" in the case of
>> +  a board providing its firmware based DTB this value can be used to override
>> +  the DTB with a different DTB.

Thanks for documenting this!

With my Debian hat on...

Reviewed-by: Vagrant Cascadian <vagrant at debian.org>


> is that really supposed to include the vendor subdir on arm64?

Yes.


> If so, adding fdtfile like that would break booting debian using its 
> flash-image. It installs dtbs without that subdir into /boot:
> /boot/dtbs/4.19.0-9-arm64/armada-3720-espressobin.dtb
>
> But it already supports $fdtfile:
> https://salsa.debian.org/installer-team/flash-kernel/-/blob/master/bootscript/arm64/bootscr.uboot-generic#L32
>
> If I read that script correctly, it would fail to boot with 
> fdtfile=marvell/armada-3720-espressobin.dtb...

Support for installing in vendor subdirs was added to flash-kernel 3.91
from 2018, and I believe the vendor subdirs are included in the
debian-installer boot media as well.


live well,
  vagrant
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