Re: [PATCH] wic: bootimg-efi-isar: Add support for loading device tree files

[Henning Schild <henning.schild@siemens.com>]

Am Mon, 11 Jul 2022 17:14:09 +0200
schrieb Jan Kiszka <jan.kiszka@siemens.com>:

> On 11.07.22 15:12, Henning Schild wrote:
> > Am Sun, 10 Jul 2022 22:51:44 +0200
> > schrieb Jan Kiszka <jan.kiszka@siemens.com>:
> >   
> >> From: Jan Kiszka <jan.kiszka@siemens.com>
> >>
> >> For device tree using systems, add support to set a custom devices
> >> tree during UEFI boot. This requires to copy the DTB file to the
> >> boot partition and to add the respective loader entries to the
> >> configuration files.
> >>
> >> Both grub and systemd-boot support only loading a specific device
> >> tree. Therefore refuse to work if DTB_FILES contains more than one
> >> entry.
> >>
> >> This has been tested with grub from bullseye and systemd from
> >> bullseye-backport. The latter is needed as only systemd 250 gained
> >> the required feature.
> >>
> >> Out of scope are overlays (only supported by systemd-boot) as well
> >> as unified kernel images (practically broken on non-x86 with
> >> current toolchains).
> >>
> >> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> >> ---
> >>  meta/classes/imagetypes_wic.bbclass           |  2 +-
> >>  .../wic/plugins/source/bootimg-efi-isar.py    | 39
> >> +++++++++++++------ 2 files changed, 29 insertions(+), 12
> >> deletions(-)
> >>
> >> diff --git a/meta/classes/imagetypes_wic.bbclass
> >> b/meta/classes/imagetypes_wic.bbclass index 61a74d4a..3a577f71
> >> 100644 --- a/meta/classes/imagetypes_wic.bbclass
> >> +++ b/meta/classes/imagetypes_wic.bbclass
> >> @@ -106,7 +106,7 @@ WICVARS += "\
> >>             ROOTFS_SIZE STAGING_DATADIR STAGING_DIR STAGING_LIBDIR
> >> TARGET_SYS TRANSLATED_TARGET_ARCH" 
> >>  # Isar specific vars used in our plugins
> >> -WICVARS += "DISTRO DISTRO_ARCH"
> >> +WICVARS += "DISTRO DISTRO_ARCH DTB_FILES"
> >>  
> >>  python do_rootfs_wicenv () {
> >>      wicvars = d.getVar('WICVARS', True)
> >> diff --git
> >> a/meta/scripts/lib/wic/plugins/source/bootimg-efi-isar.py
> >> b/meta/scripts/lib/wic/plugins/source/bootimg-efi-isar.py index
> >> a24e04f3..aff51e81 100644 ---
> >> a/meta/scripts/lib/wic/plugins/source/bootimg-efi-isar.py +++
> >> b/meta/scripts/lib/wic/plugins/source/bootimg-efi-isar.py   
> > 
> > This file is a fork from OE with very minimal non-functional
> > changes to make it into Isar. I am afraid that feature will have to
> > make it via OE. 
> 
> Right, from
> 
>  bootimg-efi-isar.py |   65
> +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed,
> 59 insertions(+), 6 deletions(-)
> 
> to
> 
>  bootimg-efi-isar.py |  104
> +++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed,
> 87 insertions(+), 17 deletions(-)

If you look carefully you will see that what you propose is the only
new feature. And most of the other code is a "trivial" grub template
... which one could shrink, but it is not worth it. In other places i
invested a lot to make it hopefully easy to maintain, not to make it
look small.

What you suggest is a pretty big change, which is going to be pretty
hard to maintain. If we really need to go down that road ... we need
testing for that.

> The problem is that OE core has no DTB_FILES, and seems like not even
> a concept of injecting DTBs via the bootloader, thus passing them to
> wic.

Then prepare an "additional boot files" patch for OE. ... but wait. It
already has "custom_cfg". There is "initrd" which can specify multiple
files to copy, so i guess all you need is to write it down differently.
Carry the generated config+yourdiff as custom_cfg and set initrd=foo to
initrd=foo;my.dtb to get that file copied, done without a patch.

Henning

> Jan
>