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

[Launchpad Bug Tracker]

This bug was fixed in the package backport-iwlwifi-dkms -
7906-0ubuntu2~19.10.1

---------------
backport-iwlwifi-dkms (7906-0ubuntu2~19.10.1) eoan; urgency=low

  * debian/patches/0006-NOUPSTREAM-backport-rename-ktime_get_boot_ns-for-v5..patch
    - fix build against v5.3. (LP: #1848922)
  * debian/patches/0005-Makefile.kernel-pass-fno-stack-clash-protection-and-.patch
    - add -fcf-protection=none when using retpoline flags. (LP: #1830961)
    - drop -fno-stack-clash-protection for it's no longer necessary.

 -- You-Sheng Yang <vicamo.yang at canonical.com>  Mon, 21 Oct 2019
20:22:27 +0800

** Changed in: backport-iwlwifi-dkms (Ubuntu Eoan)
       Status: Fix Committed => Fix Released

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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-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-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

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