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

[Sergio Durigan Junior]

On Wednesday, November 10 2021, Matthias Klose wrote:

> $ arm-linux-gnueabihf-gcc-11 -march=armv7-a+fp -c -x c /dev/null ; echo $?
> 0
>
> that works, contrary what is mentioned in comment #14

I don't understand your statement here.  I never claimed that gcc-11
"doesn't work".  I never claimed that using -march=armv7-a+fp "never
works".  I claimed that using this flag to build php8.1 doesn't seem to
work.

You can look at the build logs here:

  https://launchpad.net/~sergiodj/+archive/ubuntu/php8.1-armhf/+packages
  https://launchpadlibrarian.net/568231957/buildlog_ubuntu-jammy-armhf.php8.1_8.1.0~rc4-1ubuntu3~ppa1_BUILDING.txt.gz

This is the debdiff used in the PPA above:

https://launchpadlibrarian.net/568229387/php8.1_8.1.0~rc4-1ubuntu2_8.1.0~rc4-1ubuntu3~ppa1.diff.gz

diff -Nru php8.1-8.1.0~rc4/debian/rules php8.1-8.1.0~rc4/debian/rules
--- php8.1-8.1.0~rc4/debian/rules	2021-10-22 23:59:56.000000000 +0000
+++ php8.1-8.1.0~rc4/debian/rules	2021-11-10 17:49:57.000000000 +0000
@@ -146,7 +146,7 @@
 endif
 
 ifeq (arm-linux-gnueabihf,$(DEB_HOST_GNU_TYPE))
-  DEB_CFLAGS_MAINT_APPEND += -mfpu=vfpv3-d16
+  DEB_CFLAGS_MAINT_APPEND += -march=armv7-a+fp
 endif
 
 # Enable producing of debugging information


The error we have is this:

jump_arm_aapcs_elf_gas.S: Assembler messages:
jump_arm_aapcs_elf_gas.S:57: Error: selected processor does not support `vstmia sp,{d8-d15}' in ARM mode
jump_arm_aapcs_elf_gas.S:68: Error: selected processor does not support `vldmia sp,{d8-d15}' in ARM mode

Note that using "-mfpu=vfpv3-d16" does work, and is what php8.1 uses
right now in order to properly build in Ubuntu.

-- 
Sergio
GPG key ID: E92F D0B3 6B14 F1F4 D8E0  EB2F 106D A1C8 C3CB BF14


** Changed in: php8.1 (Ubuntu)
       Status: Incomplete => New

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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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