Re: [OE-core][PATCH 1/2] classes/recipes: remove unnecessary qemu inherit and qemu-native dependency

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Thu, 2025-04-10 at 06:31 +0000, Chen, Qi wrote:
> The postinst uses qemuwrapper which in turns uses qemu-native. But
> the postinst runs at do_rootfs time. And this dependency is ensured
> by the following line:
> meta/classes-recipe/image.bbclass:DEPENDS += "${@' '.join(["%s-
> qemuwrapper-cross" % m for m in
> d.getVar("MULTILIB_VARIANTS").split()])} qemuwrapper-cross
> depmodwrapper-cross cross-localedef-native"
> 
> PACKAGE_WRITE_DEPS  is for do_package_write_rpm/deb/ipk. These tasks
> do not run postinst and thus not using qemu-native. So 'qemu-native'
> can be removed from PACKAGE_WRITE_DEPS safely.
> 
> For the removal of qemu.bbclass inherit, these classes/recipes do not
> really use any function from this qemu.bbclass. So we can safely
> remove 'inherit qemu' for them.
> 
> My test for this patch 1/2 is: qemux86-64 + systemd + bitbake core-
> image-sato. There's no error.

Something needs to trigger the system to have qemu-native available at
do_rootfs time since these recipes write a postinstall which can use
qemu. That is what PACKAGE_WRITE_DEPS is for. I suspect you're pulling
in qemu through other dependencies but that doesn't mean this one is
unneeded.

package.bbclass has a comment about this:

# If your postinstall can execute at rootfs creation time rather than on
# target but depends on a native/cross tool in order to execute, you need to
# list that tool in PACKAGE_WRITE_DEPS. Target package dependencies belong
# in the package dependencies as normal, this is just for native/cross support
# tools at rootfs build time.
PACKAGE_WRITE_DEPS ??= ""

As for the qemu class inherit, the code used to write the qemu binary
call into the postinst but it uses qemuwrapper now which comes from
qemuwrapper-cross. I suspect you're right that it means the qemu
inherit is no longer needed however we should probably change the
inherit qemu for a PACKAGE_WRITE_DEPS += "qemuwrapper-cross"?

(and see if we could remove the dependency in image.bbclass?)

Cheers,

Richard