Re: [OE-core] [PATCH 0/6] systemd based initrd and modular kernel support

[Mikko Rapeli <mikko.rapeli@linaro.org>]

Hi,

On Mon, Mar 17, 2025 at 11:50:58AM +0000, Richard Purdie wrote:
> On Fri, 2025-03-14 at 13:19 +0200, Mikko Rapeli via lists.openembedded.org wrote:
> > systemd based initrd supports more security, encryption etc features
> > than custom shell script ones but oe-core lacks support for it.
> > Convert core-image-initramfs-boot to create systemd based initrd
> > if "systemd-initramfs" is set in DISTRO_FEATURES. Includes a test
> > for this initrd to mount rootfs via Unified Kernel Image uki.py.
> > 
> > Sadly the boot time is really slow, e.g. over 30 seconds with
> > systemd based initrd. One of the major reasons is the large
> > amount of kernel modules built into the linux-yocto kernel and
> > processing of their udev events in userspace. Thus add
> > kernel-initrd-modules meta package to easily install
> > subset of all kernel modules to initrd. The subset
> > supports "mount rootfs from any block device" but
> > doesn't include graphics, UBS etc support. Without this
> > generated meta package, initrd recipe needs to manually define
> > which exact kernel modules to include which breaks if
> > those modules are built into the kernel. Thus the initrd
> > becomes machine and kernel config specific and hard to maintain.
> > With this meta package a generic initrd can be created.
> > 
> > Separate changes to linux-yocto compile a lot more drivers
> > as modules but they depend on these initrd changes.
> > 
> > Mikko Rapeli (6):
> > � systemd: use serial-getty-generator on genericarm64
> > � systemd: enable efi support if in MACHINE_FEATURES too
> > � uki.bbclass: drop serial console from kernel command line
> > � kernel.bbclass: add kernel-initrd-modules meta package
> > � core-image-initramfs-boot: add option to build systemd based initrd
> > � oeqa selftest uki.py: add aarch64/arm test with systemd based initrd
> > 
> > �.../recipes-core/systemd/systemd_%.bbappend�� |� 3 +
> > �.../kernel-module-split.bbclass�������������� | 46 +++++++++++
> > �meta/classes-recipe/kernel.bbclass����������� |� 5 +-
> > �meta/classes-recipe/module.bbclass����������� | 37 +++++++++
> > �meta/classes-recipe/uki.bbclass�������������� |� 2 +-
> > �meta/lib/oeqa/selftest/cases/uki.py���������� | 76 +++++++++++++++++++
> > �.../images/core-image-initramfs-boot.bb������ | 28 ++++++-
> > �meta/recipes-core/systemd/systemd_257.3.bb��� |� 1 +
> > �8 files changed, 193 insertions(+), 5 deletions(-)
> > �create mode 100644 meta-yocto-bsp/recipes-core/systemd/systemd_%.bbappend
> 
> Unfortunately this series seemed to result in oe-selftest failures on
> both aarch64 and x86-64:
> 
> https://autobuilder.yoctoproject.org/valkyrie/#/builders/23/builds/1242
> https://autobuilder.yoctoproject.org/valkyrie/#/builders/48/builds/1110/steps/14/logs/stdio

Thanks, I will investigate these. I ran into various issues when executing
selftests on my aarch64 build machine.

Is the basehash error related to this series or something else?

https://autobuilder.yoctoproject.org/valkyrie/api/v2/logs/1782873/raw_inline

stdio: ERROR: When reparsing /tmp/selftest-fetchoxfe4t0p/test.bb:do_checkuri, the basehash value changed from 84b9e23a83a764e7a5d8a96ee523199e2b1c604f4280a45030e248de0ff52962 to 4123da244f465feffecb2b4fd2b132b64851981ec2fb70bf9445df8b0ea6a69e. The metadata is not deterministic and this needs to be fixed.
stdio: ERROR: The following commands may help:
stdio: ERROR: $ bitbake test -cdo_checkuri -Snone
stdio: ERROR: Then:
stdio: ERROR: $ bitbake test -cdo_checkuri -Sprintdiff
stdio: ERROR: When reparsing /tmp/selftest-fetchoxfe4t0p/test.bb:do_fetch, the basehash value changed from 6d55d6743729b615749dc016857d7e5f9c884a8b92f0d57f68e743f4910333d3 to fa7d6ea0563b60362418d2a6c5e41a6684183d01ec578b65abd0c64a9cfba7cf. The metadata is not deterministic and this needs to be fixed.
...

There are a lot of these.

If there are any boot failures in qemu then I will have a look. The changes were not
supposed to change existing rootfs or initrd images. The new test in uki.py
may fail on some configurations which I did no manage to test.
Maybe "uki.bbclass: drop serial console from kernel command line" is breaking
serial console prompt on some machines. I'll try to reproduce.

Did the test run contain the linux-yocto changes which build a lot of kernel
drivers as modules? I don't think that is ready for AB testing yet, hence RFC in
https://lists.yoctoproject.org/g/linux-yocto/message/14866
The changes were sent out in-reply-to this thread so it's possible some tool
picked them up. That could explain shell script based initrd boot error message:

ERROR: There's no '/dev' on rootfs.

Cheers,

-Mikko