[Bug 1830961] Re: Kernels & kernel drivers fail to build with gcc-9 [error: ‘-mindirect-branch’ and ‘-fcf-protection’ are not compatible]

[Daniel van Vugt]

** Also affects: nvidia-graphics-drivers-390 (Ubuntu)
   Importance: Undecided
       Status: New

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to gcc-9 in Ubuntu.
https://bugs.launchpad.net/bugs/1830961

Title:
  Kernels & kernel drivers fail to build with gcc-9 [error: ‘-mindirect-
  branch’ and ‘-fcf-protection’ are not compatible]

Status in backport-iwlwifi-dkms package in Ubuntu:
  Fix Released
Status in gcc-9 package in Ubuntu:
  Won't Fix
Status in linux package in Ubuntu:
  Fix Released
Status in nvidia-graphics-drivers-390 package in Ubuntu:
  Confirmed
Status in nvidia-graphics-drivers-430 package in Ubuntu:
  Fix Released
Status in virtualbox package in Ubuntu:
  Won't Fix
Status in xtables-addons package in Ubuntu:
  Won't Fix
Status in backport-iwlwifi-dkms source package in Eoan:
  Fix Released
Status in gcc-9 source package in Eoan:
  Won't Fix
Status in linux source package in Eoan:
  Fix Released
Status in nvidia-graphics-drivers-390 source package in Eoan:
  Confirmed
Status in nvidia-graphics-drivers-430 source package in Eoan:
  Fix Released
Status in virtualbox source package in Eoan:
  Won't Fix
Status in xtables-addons source package in Eoan:
  Won't Fix

Bug description:
  [SRU Justification for backport-iwlwifi-dkms]

  [Impact]
  FTBFS against v5.3 kernels on Eoan/Focal.

  [Fix]
  * Backport fix from upstream commit f47729b94e11 (backport: rename ktime_get_boot_ns for v5.3+).
  * Also updates -fcf-protection=none usage for bug 
  1830961.

  [Test Case]
  Verified DKMS module build on linux-oem/linux-oem-osp1/linux-generic >= 4.10 kernels on series Xenial/Bionic/Cosmic/Disco/Eoan and Focal.

  [Regression Risk]
  Low. There is no functional changes in comparison to 7906-0ubuntu1.

  ======== original bug description ========

  Compiling kernels & kernel modules fails due to these errors:

  ./include/linux/compiler.h:193:1: error: ‘-mindirect-branch’ and
  ‘-fcf-protection’ are not compatible

  (This happens with any kernel modules.)

  This appears to be due to the changes in 9.1.0-3ubuntu1 enabling -fcf-
  protection by default on 19.10's gcc-9.

  Switching to gcc-8 allows compilation to proceed.

  WORKAROUND:

  sudo ln -fs gcc-8 /usr/bin/gcc

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/backport-iwlwifi-dkms/+bug/1830961/+subscriptions