Hi Dan,
Thank you for your reply!
On 13/11/2024 18:08, Dan Carpenter wrote:
On Fri, Nov 08, 2024 at 07:21:59PM +0100, Matthieu Baerts wrote:
KSelftests from the same version
According to the doc [2], kselftests should support all previous kernel versions. The LKFT CI is then using the kselftests from the last stable release to validate all stable versions. Even if there are good reasons to do that, we would like to ask for an opt-out for this policy for the networking tests: this is hard to maintain with the increased complexity, hard to validate on all stable kernels before applying patches, and hard to put in place in some situations. As a result, many tests are failing on older kernels, and it looks like it is a lot of work to support older kernels, and to maintain this.
Many networking tests are validating the internal behaviour that is not exposed to the userspace. A typical example: some tests look at the raw packets being exchanged during a test, and this behaviour can change without modifying how the userspace is interacting with the kernel. The kernel could expose capabilities, but that's not something that seems natural to put in place for internal behaviours that are not exposed to end users. Maybe workarounds could be used, e.g. looking at kernel symbols, etc. Nut that doesn't always work, increase the complexity, and often "false positive" issue will be noticed only after a patch hits stable, and will cause a bunch of tests to be ignored.
Regarding fixes, ideally they will come with a new or modified test that can also be backported. So the coverage can continue to grow in stable versions too.
Do you think that from the kernel v6.12 (or before?), the LKFT CI could run the networking kselftests from the version that is being validated, and not from a newer one? So validating the selftests from v6.12.1 on a v6.12.1, and not the ones from a future v6.16.y on a v6.12.42.
These kinds of decisions are something that Greg and Shuah need to decide on.
Thank you, it makes sense.
You would still need some way to automatically detect that kselftest is running on an old kernel and disable the networking checks. Otherwise when random people on the internet try to run selftests they would run into issues.
Indeed. I guess we can always add a warning when the kernel and selftests versions are different. I suppose the selftests are built using the same kernel version, then executed on older versions: we could then compare the kernel versions at build time and run time, no?
Regarding the other questions from my previous email -- skipped tests (e.g. I think Netfilter tests are no longer validated), KVM, notifications -- do you know who at Linaro could eventually look at them?
Cheers, Matt