Running kernel 5.0.0-31-generic in a Eoan install I get the following
error when I try to install lttng-modules-dkms:
CC [M]
/var/lib/dkms/lttng-modules/2.10.8/build/lib/ringbuffer/ring_buffer_backend.o
In file included from ./include/linux/export.h:45,
from ./include/linux/linkage.h:7,
from ./include/linux/kernel.h:7,
from ./include/linux/list.h:9,
from ./include/linux/module.h:9,
from
/var/lib/dkms/lttng-modules/2.10.8/build/lib/ringbuffer/ring_buffer_backend.c:2
2:
./include/linux/compiler.h: In function ‘__read_once_size’:
./include/linux/compiler.h:192:1: error: ‘-mindirect-branch’ and
‘-fcf-protection’ are not compatible
192 | {
| ^
With kernel 5.0.0-32-generic the modules are built and loaded successfully.
Therefore I'm marking verification-done for Disco.
** Tags removed: verification-needed-disco
** Tags added: verification-done-disco
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Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1843291
Title:
Add -fcf-protection=none when using retpoline flags
Status in linux package in Ubuntu:
In Progress
Status in linux source package in Bionic:
Fix Committed
Status in linux source package in Disco:
Fix Committed
Bug description:
SRU Justification
Impact: Starting in eoan -fcf-protection is enabled by default in gcc,
see https://wiki.ubuntu.com/ToolChain/CompilerFlags. This option is
incompatible with -mindirect-branch, which is used for building
kernels with retpoline support. Building a kernel or dkms modules
fails without the patch, and during upgrade to eoan we can get
failures due to dkms modules failing to build for older kernels with
the new compiler.
Fix: Backport upstream patch to add -fcf-protection=none to kernel
retpoline flags.
Test Case: Upgrade from {bionic,diso} to eoan with dkms modules
installed.
Regression Potential: The patch probes the compiler for support for
-fcf-protection and only adds it if the compiler supports it, and
=none was the default prior to the change in eoan. It's also been
upstream and in eoan for a while now, so it's unlikely to cause any
regressions.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1843291/+subscriptions
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