Hello Kai, I'm not an expert, but will try my best to respond. On Thu, 2021-09-23 at 22:51 +0800, Kai Liu wrote:

Hi,

While looking at boo, I noticed that the kernel and initrd of the VM workers are different for different jobs.

For example, for SLES, qemu uses the kernel and initrd under /var/cache/obs/worker/root_*/.mount/boot/kernel. But for CentOS, it uses kernel under /boot. It looks like the SLES worker even runs the exact kernel version of the target OS.

SUSE distributions (SLES, openSUSE, etc.) use the kernel-obs-build package. I don't know the exact difference between the kernel-default and the kernel-obs- build packages, but this package is what provides the /var/cache/obs/worker/* kernel and initrd for SUSE distributions. For non-SUSE distributions, there is no kernel-obs-build package yet, as far as I'm told. OBS seems to be using some sort of a workaround to provide the kernels in the /boot/ directory of the worker host machine. If your question is related to your private OBS instance, then if you check your /etc/sysconfig/obs-server you should find an option to define your own kernel and initrd: https://github.com/openSUSE/open-build-service/blob/master/dist/sysconfig.ob... https://github.com/openSUSE/open-build-service/blob/master/dist/sysconfig.ob... Regards, Srinidhi.

On 2021/09/23 Thu 15:22, Srinidhi B wrote:

Hello Kai,

I'm not an expert, but will try my best to respond.

On Thu, 2021-09-23 at 22:51 +0800, Kai Liu wrote:

...

Hi,

While looking at boo, I noticed that the kernel and initrd of the VM workers are different for different jobs.

For example, for SLES, qemu uses the kernel and initrd under /var/cache/obs/worker/root_*/.mount/boot/kernel. But for CentOS, it uses kernel under /boot. It looks like the SLES worker even runs the exact kernel version of the target OS.

SUSE distributions (SLES, openSUSE, etc.) use the kernel-obs-build package. I don't know the exact difference between the kernel-default and the kernel-obs- build packages, but this package is what provides the /var/cache/obs/worker/* kernel and initrd for SUSE distributions.

For non-SUSE distributions, there is no kernel-obs-build package yet, as far as I'm told. OBS seems to be using some sort of a workaround to provide the kernels in the /boot/ directory of the worker host machine.

If your question is related to your private OBS instance, then if you check your /etc/sysconfig/obs-server you should find an option to define your own kernel and initrd:

https://github.com/openSUSE/open-build-service/blob/master/dist/sysconfig.ob... https://github.com/openSUSE/open-build-service/blob/master/dist/sysconfig.ob...

Thanks. My original question was related. Here in this file the kernel and initrd can be appointed. But it's a machine-wide option, means every worker VM on this machines will use the same kernel & initrd to boot. Thus you will end up building a CentOS package with SLES kernel, for example. This is what I would like to solve, by following how it's done on boo. Regards, Kai

On Thu, 2021-09-23 at 23:42 +0800, Kai Liu wrote:

Thanks. My original question was related. Here in this file the kernel and initrd can be appointed. But it's a machine-wide option, means every worker VM on this machines will use the same kernel & initrd to boot. Thus you will end up building a CentOS package with SLES kernel, for example. This is what I would like to solve, by following how it's done on boo.

Correct. If you want to set different kernel and initrd per build, then you need to follow what Andreas recommended - check what boot-vm-kvm does. By following that script, I recently managed to configure a worker to build CentOS packages on SLES nodes: * Install kernel-obs-build on the worker node * sudo ln -s /.build.kernel.kvm /boot/kernel.obs.guest * sudo ln -s /.build.initrd.kvm /boot/initrd.obs.guest I don't know if this is the correct way of doing things or not, but this is currently working in one of our private OBS instances. This way when boot-vm-kvm does not find the kernel under the build root, it will look for /boot/*.obs.guest files. https://github.com/openSUSE/obs-build/commit/a9b7da4a3ed2ea9bdc8ea0606fca146... Regards, Srinidhi.

On Donnerstag, 23. September 2021, 17:59:48 CEST Srinidhi B wrote:

On Thu, 2021-09-23 at 23:42 +0800, Kai Liu wrote:

...

Thanks. My original question was related. Here in this file the kernel and initrd can be appointed. But it's a machine-wide option, means every worker VM on this machines will use the same kernel & initrd to boot. Thus you will end up building a CentOS package with SLES kernel, for example. This is what I would like to solve, by following how it's done on boo.

Correct. If you want to set different kernel and initrd per build, then you need to follow what Andreas recommended - check what boot-vm-kvm does.

By following that script, I recently managed to configure a worker to build CentOS packages on SLES nodes:

* Install kernel-obs-build on the worker node * sudo ln -s /.build.kernel.kvm /boot/kernel.obs.guest * sudo ln -s /.build.initrd.kvm /boot/initrd.obs.guest

I don't know if this is the correct way of doing things or not, but this is currently working in one of our private OBS instances.

kernel-obs-build is supposed to get installed inside of the VM. No need for using the .guest links, these are just very last resort hacks..

This way when boot-vm-kvm does not find the kernel under the build root, it will look for /boot/*.obs.guest files.

https://github.com/openSUSE/obs-build/commit/a9b7da4a3ed2ea9bdc8ea0606fca146...

Regards, Srinidhi.

-- Adrian Schroeter Build Infrastructure Project Manager SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nuernberg, Germany (HRB 247165, AG München), Geschäftsführer: Felix Imendörffer

On Sep 23 2021, Neal Gompa wrote:

Is it possible for it to use the standard kernels instead of the kernel-obs-build stuff? I'd much rather reuse the standard kernel builds...

kernel-obs-build _is_ the standard kernel, just repackaged and equipped with an initrd. Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 "And now for something completely different."

On Sep 23 2021, Neal Gompa wrote:

On Thu, Sep 23, 2021 at 2:30 PM Andreas Schwab wrote:

...

On Sep 23 2021, Neal Gompa wrote:

...

Is it possible for it to use the standard kernels instead of the kernel-obs-build stuff? I'd much rather reuse the standard kernel builds...

kernel-obs-build _is_ the standard kernel, just repackaged and equipped with an initrd.

So we just need a package that includes a prebuilt initramfs?

Yes, that's the main point of kernel-obs-build. Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 "And now for something completely different."

On 23.09.21 17:22, Srinidhi B wrote:

Hello Kai,

I'm not an expert, but will try my best to respond.

On Thu, 2021-09-23 at 22:51 +0800, Kai Liu wrote:

...

Hi,

While looking at boo, I noticed that the kernel and initrd of the VM workers are different for different jobs.

For example, for SLES, qemu uses the kernel and initrd under /var/cache/obs/worker/root_*/.mount/boot/kernel. But for CentOS, it uses kernel under /boot. It looks like the SLES worker even runs the exact kernel version of the target OS.

SUSE distributions (SLES, openSUSE, etc.) use the kernel-obs-build package. I don't know the exact difference between the kernel-default and the kernel-obs- build packages, but this package is what provides the /var/cache/obs/worker/* kernel and initrd for SUSE distributions.

For non-SUSE distributions, there is no kernel-obs-build package yet, as far as I'm told. OBS seems to be using some sort of a workaround to provide the kernels in the /boot/ directory of the worker host machine.

https://github.com/seife/kernel-obs-build https://build.opensuse.org/package/show/home:seife:kiwitest-centos/kernel-ob... Without that, building CentOS-7 images with KIWI was hard/impossible or needed crazy workarounds IIRC. I never got past building this for CentOS-7, because I fortunately did not need it for anything else ;-) -- Stefan Seyfried "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." -- Richard Feynman