Re: [Discuss OpenCPI] Ubuntu Host Building Kernel Module

From: James Kulp <jek_at_parera.com>
Date: Mon, 26 Oct 20 13:45:47 -0400

On 10/26/20 1:21 PM, Brian Padalino wrote:
> I've noticed on multiple occasions that oftentimes I will build a different
> branch of OpenCPI after my system has been running for a while, and when
> the test for the kernel module comes around, it will fail. The issue is
> that /usr/src has newer linux headers than the current kernel that is
> running.
>
> I suspect these headers get updated/installed during the apt check at the
> beginning of the deps script, but I am not sure.
>
> I am also not sure what the solution should be:
>
> - Error out of build when mismatch is detected
> - Build against the currently running linux kernel headers
> - Build against the latest linux kernel headers installed (current
> solution)
>
> Obviously the current solution causes me to reboot my machine, and re-build
> to update. Maybe that's the best solution, though it doesn't tell me that
> the mismatch occurred - I just need to realize what happened and take an
> appropriate step to fix it?

There are a number of checks in the kernel driver build that tries to
understand the difference between the running kernel and the most
recently installed one.
But perhaps they are too centos specific.  We don't really take care of
dealing with building drivers for older kernels, although there is an
environment variable to force the issue.
What behavior would you want?  A knob that forces the build to target
the currently running kernel?

The RPM installation machinery tries to be even more clever and rebuild
the driver at the time a newer kernel is rebooted.


>
> As an ancillary question, is there a way to update just the kernel module
> during the build? I am using ./scripts/install-opencpi.sh - is there
> another script to run, or arguments that I can run to just re-build the
> kernel module and test just the kernel module?

"make driver" in the root directory is the "internal" way to do it, but
that is not stable or documentable that way.

Jim



>
> Thanks,
> Brian
>


Received on Mon Oct 26 2020 - 17:45:47 CDT