[CentOS] C7 Kernel module compilation

[Akemi Yagi]

On Wed, Aug 7, 2019 at 11:00 PM Alessandro Baggi
<alessandro.baggi at gmail.com> wrote:
>
> Il 07/08/19 20:15, Akemi Yagi ha scritto:
> > On Wed, Aug 7, 2019 at 9:00 AM Alessandro Baggi
> > <alessandro.baggi at gmail.com> wrote:
> >>
> >> Il 07/08/19 01:02, Phil Perry ha scritto:
> >>> On 06/08/2019 14:45, Alessandro Baggi wrote:
> >
> >>> Please post the actual error message in dmesg or /var/log/messages.
> >>>
> >>> It's likely that the kernel is just grumbling that the module is not
> >>> signed (missing key), but it's just noise unless you're using
> >>> SecureBoot. Posting the actual message in full will help determine if
> >>> that is the case.
> >>>
> >>> Thanks
> >>>
> >>> Phil
> >>
> >> Hi, thank you for your reply,
> >> I solve adding in "General Setup" values of current kernel on
> >> localversion option and adding Module.symver from
> >> /boot/symver-version.gz to module directory.
> >>
> >> Now I get another problem compiling the third party module (i2c-nct6775):
> >>
> >> "CONFIG_RETPOLINE=y but not supported by the compiler. Compiler update
> >> recomended. Stop."
> >>
> >> I tried using scl gcc7 and 8 but get the same issue.
> >>
> >> I checked that retpoline is related to Spectre but checking on centos with:
> >>
> >> cat /sys/devices/system/cpu/vulnerabilities/spectre_v2
> >>
> >> I get:
> >>
> >> Mitigation: IBRS (kernel), IBPB
> >>
> >> and RETPOLINE seems disabled (I'm wrong?).
> >>
> >> I ridden in a blog post that I can disable this check commenting out
> >> some lines starting from N. 166 of arch/Makefile but I don't think this
> >> is the best approach.
> >>
> >> At this point I can't understand what means the previous error and why I
> >> get this error when compiling i2c-nct6775.
> >>
> >> Can someone point me in the right direction?
> >
> > Please post the output from:
> >
> > rpm -qa kernel\* | sort
> >
> > and
> >
> > uname -r
> >
> > Akemi
>
> kernel-3.10.0-957.12.1.el7.x86_64
> kernel-3.10.0-957.12.2.el7.x86_64
> kernel-3.10.0-957.21.3.el7.x86_64
> kernel-3.10.0-957.27.2.el7.x86_64
> kernel-3.10.0-957.el7.x86_64
> kernel-devel-3.10.0-957.21.3.el7.x86_64
> kernel-devel-3.10.0-957.27.2.el7.x86_64
> kernel-headers-3.10.0-957.27.2.el7.x86_64
> kernel-ml-5.1.0-1.el7.elrepo.x86_64
> kernel-ml-devel-5.1.0-1.el7.elrepo.x86_64
> kernel-tools-3.10.0-957.27.2.el7.x86_64
> kernel-tools-libs-3.10.0-957.27.2.el7.x86_64
> kernel-tools-libs-devel-3.10.0-957.27.2.el7.x86_64
>
>
> 3.10.0-957.27.2.el7.x86_64

So, you tried to build the i2c-nct6775 module against
kernel-3.10.0-957.27.2.el7 under the running kernel 3.10.0-957.27.2
and you have a matching version of kernel-devel. Then I don't quite
understand why you get the "not supported by the compiler" error...

Akemi