Re: [Buildroot] [PATCH 0/3] {linux, linux-headers}: add support for 6.12

From: Sergey Matyukevich <geomatsi@gmail.com>
To: Edgar Bonet <bonet@grenoble.cnrs.fr>
Cc: buildroot@buildroot.org
Subject: Re: [Buildroot] [PATCH 0/3] {linux, linux-headers}: add support for 6.12
Date: Tue, 10 Dec 2024 23:43:11 +0300	[thread overview]
Message-ID: <Z1in3yM7ddVMYEqq@curiosity> (raw)
In-Reply-To: <dcbd3f77-e737-41a2-9f23-87141d0bdf9b@grenoble.cnrs.fr>

Hi Edgar,

On Mon, Dec 09, 2024 at 09:11:40AM +0100, Edgar Bonet wrote:
> Hello everybody!
> 
> Sergey Matyukevich wrote:
> > I have been waiting for the new LTS Linux v6.12 in Buildroot to start
> > sending Christmas updates for some of my OrangePi boards. Now v6.12.3
> > is already available, but the latest kernel is still have 6.11.x. So I
> > decided to undertake a copy-paste exercise using the latest kernel and
> > headers update series by Bernd.
> 
> Nice!
> 
> Note, however, that there is an issue with Linux v6.12: the kernel build
> process won't build the device trees provided by Buildroot. The issue
> has been raised by Chris Packham both on the Buildroot mailing list[1]
> and on the kernel mailing list.[2] I think this should be fixed before
> bumping "latest kernel" to v6.12.
> 
> In the kernel thread, there is this solution suggested by Masahiro
> Yamada:
> 
> > I have [the yet-to-upstream device tree files] in the proper directory
> > location, and add
> >
> >   dtb-$(CONFIG_ARCH_FOO)  += foo-downstream-custom1.dtb
> >   dtb-$(CONFIG_ARCH_FOO)  += foo-downstream-custom2.dtb
> >     ...
> >
> > just like how they would look when they were upstreamed.
> 
> Maybe this approach could be adapted to Buildroot?

IIUC at the moment Buildroot includes the following configurations that
make use of BR2_LINUX_KERNEL_CUSTOM_DTS_PATH:
- acmesystems_acqua_a5_256mb_defconfig (v6.6)
- acmesystems_acqua_a5_512mb_defconfig (v6.6)
- octavo_osd32mp1_brk_defconfig (v5.10)
- octavo_osd32mp1_red_defconfig (v5.10)
- s6lx9_microboard_defconfig (v4.4.7)

Kernel version from each config is specified in parentheses. Adding new
v6.12 kernel is not going to break any of those boards right away.

However if the build rule for drop-in dtbs will not be re-enabled (which
seems likely), migration to new kernels will be a problem for those boards.
I don't see how BR2_LINUX_KERNEL_CUSTOM_DTS_PATH can be supported in this
case w/o patching new kernels. Probably it makes sense to convert those
out-of-tree dts files into proper kernel patches ?

Regards,
Sergey
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