[LU-7643] Remove kernel version string from Lustre release field

• Type: Technical task
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.9.0
• Labels: llnl patch
• Assignee: Minh Diep
• Reporter: Christopher Morrone (Inactive)

Description

Right now when RPM packages are built, we insert into Lustre's release field the version string from the kernel against which Lustre was built. For instance:

$ rpm -qpi lustre-2.7.0-2.6.32_504.8.1.el6_lustre.x86_64.x86_64.rpm 
Name        : lustre
Version     : 2.7.0
Release     : 2.6.32_504.8.1.el6_lustre.x86_64

Side note: A sysadmin is going to (and have in the past) think we messed up because of the ".x86_64.x86_64" in the file name, but the reason for it is that the first one is part of the Linux kernel version string, as we can see in the Release field above. The second .x86_64 is Lustre's.

The reason for including the kernel's version string in Lustre's Release field because Lustre has traditionally been packaged to work with one, and only one, specific version of a kernel. If you have two very slightly different kernel versions "2.6.32_504.8.1.el6" and "2.6.32_504.8.2.el6", for instance, then you currently need to compile lustre against both kernels individually. While the "rpm -requires" should also list the specific required version number, because there are so many very closely compatible kernels for which we need to juggle lustre builds, it was simpler for sysadmins and developers alike to add the kernel's version string into Lustre's release field.

But fortunately, this need to build lustre for every specific kernel is a self-imposed restriction, and work is under way to lift that restriction in LU-5614.

For many years, it has been possible to compile kernel modules once and then use them with any kernel that is ABI compatible. The Linux distro mechanism that allows this is often called "weak modules". LU-5614 should bring Lustre into the year 2006 and get it working with weak modules.

Once that is done, we can finally drop the kernel version string.

This is especially fortuitous for anyone using koji as a build system, because koji makes this sort of abuse of standard packaging practice pretty close to impossible. koji is used by fedora and its cousins, and it has also been adopted by LLNL for its RHEL-based TOSS distribution.

Issue Links

• is blocked by: LU-5614 use %kernel_module_package for weak-updates
• is blocked by: LU-7699 Overhaul lustre's versioning
• is blocking: LU-7645 Stop controlling the RPM Release field from Lustre's build system
• is related to: LU-8343 build failures on SLES
• is related to: LU-20 patchless server kernel

Comments

[Cory Spitz]

FYI:
http://cdn.opensfs.org/wp-content/uploads/2016/04/LUG2016D1_Improved-Versioning_Morrone_DiNatale.pdf
https://www.youtube.com/watch?v=50VN9Q7BHYA&index=5&list=PLA5dHg1_l3V8r6eqrUnl8DiB-KH1K5yLH

[Joseph Gmitter (Inactive)]

reopening to fix fields to show up in 2.9.0 changelog

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch http://review.whamcloud.com/19954/
Subject: LU-7643 build: Remove Linux version string from RPM release field
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 28c17d40e5a597a3d2f10f1f43039ef92425954e

[Christopher Morrone (Inactive)]

I'm not really on board with adding a dependency that won't function correctly.

[Bob Glossman (Inactive)]

even if having a proper Requires permits (incorrect) weak-updates links of osd-ldiskfs in other not really matching kernels that happen to be installed, having the Requires at least gives better tracking of exactly which kernel version the particular osd-ldiskfs was derived from and is intended for.

While I would really prefer enforcement I want to at least have visibility into the dependency.

[Christopher Morrone (Inactive)]

Yeah, but as we got to later in the discussion, that isn't very useful. I think I have to retract that offer.

Just having that one kernel installed doesn't stop the osd-ldiskfs package's modules from being used in any of the other kernels that are also installed. The weak-updates system will still symlink the modules into all kernels with compatible symbols.

[Bob Glossman (Inactive)]

Christopher,
You are probably correct. I may have been thinking of some other change.

If you go ahead and add a kernel version Requires for osd-ldiskfs as discussed in earlier comments I will be satisfied with that.

[Christopher Morrone (Inactive)]

Bob, I think you may be thinking of another change. Change 19954 does not delete any Requires or Provides.

[Bob Glossman (Inactive)]

That's just it. These changes also delete Requires and Provides in packages too. Can't figure out dependencies using rpm queries either.

[James A Simmons]

So the question related to the patch for this ticket is does having the kernel name string in the rpm provide any gain. I would say no. Not landing this patch will not change the kernel version dependency issues. Even when we resolve the dependency issues does having the kernel version string in the release field improve anything. Again I would say no. You can figure out kernel dependency using rpm queries instead.