+++ Will McVicker [21/01/21 21:36 +0000]:
Config MODULE_SCMVERSION introduces a new module attribute -- `scmversion` -- which can be used to identify a given module's SCM version. This is very useful for developers that update their kernel independently from their kernel modules or vice-versa since the SCM version provided by UTS_RELEASE (`uname -r`) will now differ from the module's vermagic attribute. For example, we have a CI setup that tests new kernel changes on the hikey960 and db845c devices without updating their kernel modules. When these tests fail, we need to be able to identify the exact device configuration the test was using. By including MODULE_SCMVERSION, we can identify the exact kernel and modules' SCM versions for debugging the failures. Additionally, by exposing the SCM version via the sysfs node /sys/module/MODULENAME/scmversion, one can also verify the SCM versions of the modules loaded from the initramfs. Currently, modinfo can only retrieve module attributes from the module's ko on disk and not from the actual module that is loaded in RAM. You can retrieve the SCM version in two ways, 1) By using modinfo: > modinfo -F scmversion MODULENAME 2) By module sysfs node: > cat /sys/module/MODULENAME/scmversion
Hi Will, First off, thanks for being patient and being responsive throughout the patch review process. Personally, I am rather neutral towards this feature. We already provide CONFIG_MODULE_SRCVERSION to provide a checksum of a module's source files and I think the SCMVERSION is a nicer alternative. I can see how an optional scmversion field might be helpful information for distro developers in testing environments and in situations where it is possible for the kernel and modules to be updated/packaged separately (for instance, the kernel selftest modules under lib/ are in-tree modules that are provided as a separate kernel module package in SLE). Generally, out of principle, I do not want to merge a patch that's been NAK'd repeatedly; even if I take the patch it'd likely be contested all the way up to the merge window. So this boils down to whether Christoph (and maybe Greg) are fine with this being a debug option that's not enabled by default. Thanks, Jessica
