Hi Shuah, On 1/31/2022 12:34 PM, Shuah Khan wrote: > On 1/31/22 12:37 PM, Reinette Chatre wrote: >> On 1/26/2022 12:13 PM, Shuah Khan wrote: >>> Update the document to clarifiy support for running mainline >>> kselftest on stable releases and the reasons for not removing >>> test code that can test older kernels. >>> >>> Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> >>> --- >>> Documentation/dev-tools/kselftest.rst | 8 ++++++++ >>> 1 file changed, 8 insertions(+) >>> >>> diff --git a/Documentation/dev-tools/kselftest.rst b/Documentation/dev-tools/kselftest.rst >>> index dcefee707ccd..a833ecf12fbc 100644 >>> --- a/Documentation/dev-tools/kselftest.rst >>> +++ b/Documentation/dev-tools/kselftest.rst >>> @@ -7,6 +7,14 @@ directory. These are intended to be small tests to exercise individual code >>> paths in the kernel. Tests are intended to be run after building, installing >>> and booting a kernel. >>> +Kselftest from mainline can be run on older stable kernels. Running tests >>> +from mainline offers the best coverage. Several test rings run mainline >>> +kselftest suite on stable releases. The reason is that when a new test >>> +gets added to test existing code to regression test a bug, we should be >>> +able to run that test on an older kernel. Hence, it is important to keep >>> +code that can still test an older kernel and make sure it skips the test >>> +gracefully on newer releases. >>> + >>> You can find additional information on Kselftest framework, how to >>> write new tests using the framework on Kselftest wiki: >>> >> >> (My apologies if this is already documented, I was not able to find this guidance >> in Documentation/dev-tools/kselftest.rst nor when looking at the >> "Kselftest use-cases..." slides linked from https://kselftest.wiki.kernel.org/) >> >> Could you please clarify what the requirement/expectation is regarding fixes >> to tests? Since the recommendation in the above change is that Kselftest from >> mainline should be run on older stable kernels, is it required to backport >> fixes to the tests themselves to stable kernels? >> > > Couple of things to consider. > > - A new test gets added to regression test a bug in stable and mainline > - A new test gets added to test a kernel module/feature/API that has been > supported by stable and mainline releases > > In both of these cases, running mainline kselftest on stables gives you the > best coverage. > > Kselftest fixes get pulled into stables like any other kernel fixes. If a few > fixes are missing, it is a good idea to back-port if they fall into above two > categories. If the test is for a new feature then, it doesn't make sense to > back-port. > > Hope this is helpful. This is helpful, thank you very much. In summary I understand this to mean that when testing a stable kernel it is recommended to run tests from mainline, but running the tests from the same stable kernel version as the kernel being tested is also a supported use case and thus fixes to tests should be back-ported. Thank you Reinette
