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

[Tom Rini]

On Thu, Sep 03, 2020 at 07:50:32PM +0200, Andre Heider wrote:
> Hi Dennis,
> 
> 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.
> 
> is that really supposed to include the vendor subdir on arm64?
> 
> 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...

Ugh.  I thought vendors were not supposed to flatten the dtbs as
installed.  Did that change?

-- 
Tom
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