[Bug 1939379] Re: ARM kernel builds fail with GCC 11

[Michael Hudson-Doyle]

FWIW I fixed a similar issue in supertuxkart recently by patching the .S
file to have a ".fpu vfp" directive in it -- although probably ".arch
armv7-a+fp" would have been more appropriate.

It does seem strange that "gcc -march foo bar.s" does not pass -march to
the assembler but I have no real idea if that expectation is grounded in
reality -- when compiling C, the value of march is passed to the
assembler via a directive so maybe "march" is really only an argument to
gcc when gcc is doing the compiling and not when it is being used as a
frontend to the assembler.

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https://bugs.launchpad.net/bugs/1939379

Title:
  ARM kernel builds fail with GCC 11

Status in gcc-11 package in Ubuntu:
  Confirmed
Status in gcc-defaults package in Ubuntu:
  Invalid
Status in php8.1 package in Ubuntu:
  New

Bug description:
  While this might be a kernel build problem (see LP: #1939308) I wanted
  to raise the issue against the toolchain just so we can make sure it's
  *not* a toolchain bug. Basically the following behavior changed from
  gcc 10:

  $ arm-linux-gnueabihf-gcc-10 -march=armv7-a -c -x c /dev/null ; echo $?
  0

  $ arm-linux-gnueabihf-gcc-11 -march=armv7-a -c -x c /dev/null ; echo $?
  cc1: error: ‘-mfloat-abi=hard’: selected architecture lacks an FPU
  1

  Presumably the GCC 11 hard-float compiler now enforces the default
  config --with-float=hard?

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