Re: [PATCH 2/2] prefix DTB files with PN in deploy dir

["'MOESSBAUER, Felix' via isar-users" <isar-users@googlegroups.com>]

On Fri, 2026-04-10 at 15:38 +0200, Jan Kiszka wrote:
> On 10.04.26 15:22, Felix Moessbauer wrote:
> > As the changing of the DEPLOY_DIR_IMAGE has proven to be fundamentally
> > incompatible with custom initrd recipes, this patch was reverted,
> > re-introducing the do_copy_boot_files error on DTBs that are named
> > equally but belong to different mc targets.
> > 
> > To mitigate this limitation without breaking custom initrds, we prefix
> > all DTB files with ${PN}-${DISTRO} when deploying to DEPLOY_IMAGE_DIR.
> > On imaging, these prefixes are stripped again by the imager scripts.
> > 
> > Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> > ---
> >  RECIPE-API-CHANGELOG.md                       | 20 +++++++++++++++++++
> >  meta/classes-recipe/image.bbclass             |  6 ++++--
> >  meta/classes-recipe/imagetypes_wic.bbclass    |  2 +-
> >  .../wic/plugins/source/bootimg-efi-isar.py    |  3 ++-
> >  4 files changed, 27 insertions(+), 4 deletions(-)
> > 
> > diff --git a/RECIPE-API-CHANGELOG.md b/RECIPE-API-CHANGELOG.md
> > index 0e6a3172..856da5de 100644
> > --- a/RECIPE-API-CHANGELOG.md
> > +++ b/RECIPE-API-CHANGELOG.md
> > @@ -981,3 +981,23 @@ fragment, this can be specified via adding `${S}/path/to/fragment.cfg` to
> >  `KERNEL_CONFIG_FRAGMENTS`. If a fragment was checked out into ${WORKDIR} as
> >  part of a repository, a tarball, or some other directory structure, just
> >  specify it relative to ${WORKDIR} in `KERNEL_CONFIG_FRAGMENTS`.
> > +
> > +Changes in next
> > +---------------
> > +
> > +### Prefix DTB file names when deploying
> > +
> > +DTB files are now placed in the ${DEPLOY_DIR_IMAGE} with a prefix of
> > +${PN}-${DISTRO}. During wic imaging, the prefix is removed again, so no changes
> > +to downstream wks files are needed (i.e. `dtb=my-device-tree.dtb` is not
> > +affected by this change). Custom imaging plugins need to be adapted to this
> > +change by removing the prefix from the filename. For that, the variable
> > +DTB_PREFIX is exported as bitbake var into wic environment.
> > +
> > +This fixes errors when building different distros with the same machine,
> > +whereby previously the following error occured:
> > +
> > +do_copy_boot_files: The recipe isar-image-base is trying to install
> > +files into a shared area when those files already exists. It happens
> > +when some files have the same names (e.g., dtb files) for different
> > +distros.
> > diff --git a/meta/classes-recipe/image.bbclass b/meta/classes-recipe/image.bbclass
> > index 26a4ec06..9b5dd23e 100644
> > --- a/meta/classes-recipe/image.bbclass
> > +++ b/meta/classes-recipe/image.bbclass
> > @@ -379,7 +379,8 @@ EOF
> >  KERNEL_IMG = "${PP_DEPLOY}/${KERNEL_IMAGE}"
> >  INITRD_IMG = "${PP_DEPLOY}/${INITRD_DEPLOY_FILE}"
> >  # only one dtb file supported, pick the first
> > -DTB_IMG = "${PP_DEPLOY}/${@(d.getVar('DTB_FILES').split() or [''])[0]}"
> > +DTB_PREFIX = "${PN}-${DISTRO}."
> > +DTB_IMG = "${PP_DEPLOY}/${DTB_PREFIX}${@os.path.basename((d.getVar('DTB_FILES').split() or [''])[0])}"
> >  
> >  do_copy_boot_files[cleandirs] += "${DEPLOYDIR}"
> >  do_copy_boot_files[sstate-inputdirs] = "${DEPLOYDIR}"
> > @@ -402,7 +403,8 @@ do_copy_boot_files() {
> >              die "${file} not found"
> >          fi
> >  
> > -        cp -f "$dtb" "${DEPLOYDIR}/"
> > +        dtb_name=$(basename "$dtb")
> > +        cp -f "$dtb" "${DEPLOYDIR}/${DTB_PREFIX}$dtb_name"
> 
> Let's but the DTBs in prefix-subdirs - will also make referring to them
> cleaner.

I explicitly decided against putting them in subdirs to not diverge
from the names of the other artifacts. However, OE deploys the DTBs via
the devicetree class to ${IMAGE_DEPLOY_DIR}/devicetree/ , which does
not help much as we still would get a clash. In addition, it deploys to
sysroot where other recipes should consume it from [1]. But we could do
that cleanup while we are at it.

Another reason for not putting them in a directory are file globs
commonly used in CI to copy out all files in the deploy dir.

[1]
https://docs.yoctoproject.org/dev/ref-manual/classes.html#devicetree

Apart from that, OE anyways discourages direct deploy to
DEPLOY_DIR_IMAGE. Instead the deploy.bbclass class should be used to
deploy through the sstate cache.

> 
> >      done
> >  }
> >  addtask copy_boot_files before do_rootfs_postprocess after do_rootfs_install
> > diff --git a/meta/classes-recipe/imagetypes_wic.bbclass b/meta/classes-recipe/imagetypes_wic.bbclass
> > index dd6c501d..c0813223 100644
> > --- a/meta/classes-recipe/imagetypes_wic.bbclass
> > +++ b/meta/classes-recipe/imagetypes_wic.bbclass
> > @@ -107,7 +107,7 @@ 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 KERNEL_FILE MACHINE"
> > +WICVARS += "DISTRO DISTRO_ARCH KERNEL_FILE MACHINE DTB_PREFIX"
> >  
> >  python do_rootfs_wicenv () {
> >      wicvars = d.getVar('WICVARS')
> > 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 6bc78d42..32b220fa 100644
> > --- a/meta/scripts/lib/wic/plugins/source/bootimg-efi-isar.py
> > +++ b/meta/scripts/lib/wic/plugins/source/bootimg-efi-isar.py
> > @@ -57,7 +57,8 @@ class BootimgEFIPlugin(SourcePlugin):
> >          if dtb:
> >              if ';' in dtb:
> >                  raise WicError("Only one DTB supported, exiting")
> > -            cp_cmd = "cp %s/%s %s" % (bootimg_dir, dtb, hdddir)
> > +            dtb_file = "%s%s" % (get_bitbake_var("DTB_PREFIX"), dtb)
> > +            cp_cmd = "cp %s/%s %s/%s" % (bootimg_dir, dtb_file, hdddir, dtb)
> >              exec_cmd(cp_cmd, True)
> >  
> >      @classmethod
> 
> DTBs are the most prominent conflicts with multiconfigs or partial
> rebuilds. We may mitigate this one, so it's fine, but the fundamental
> risk will remain. One of the reason why I asked to study OE carefully
> and try to learn from it first.

In OE these problems are also not solved. Even the split of the TMPDIR
is done in downstream layers, not OE-core (at least I found nothing in
OE core).

Felix

> 
> Jan
> 
> -- 
> Siemens AG, Foundational Technologies
> Linux Expert Center

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