coreboot

With coreboot master 4.12-1133-g4d38c7546c on Ubuntu 20.04 on Power 8 make what-jenkins-does fails with the error below.

*** Building CMOCKA ***
[…]
[ 90%] Built target proc_uptime
Scanning dependencies of target uptime
[ 95%] Building C object example/mock/uptime/CMakeFiles/uptime.dir/uptime.c.o
[100%] Linking C executable uptime
[100%] Built target uptime
In file included from src/include/console/console.h:7,
                 from src/include/assert.h:7,
                 from src/lib/string.c:1:
src/arch/x86/include/arch/cpu.h:278:1: error: 'regparm' attribute directive ignored [-Werror=attributes]
  278 | asmlinkage void car_stage_entry(void);
      | ^~~~~~~~~~
In file included from src/include/assert.h:7,
                 from src/lib/string.c:1:
src/include/console/console.h:38:1: error: 'regparm' attribute directive ignored [-Werror=attributes]
   38 | asmlinkage void console_init(void);
      | ^~~~~~~~~~
cc1: all warnings being treated as errors
make[1]: *** [tests/Makefile.inc:102: build/tests/lib/string-test/src/lib/string.o] Error 1