kumquat-buildroot/board/qemu/mips64r6-malta
Romain Naour 5259a39c7a configs/qemu_mips64r6: fix Linux kernel build with gcc 10.x
From [1]

"GCC 10 (PR 91233) won't silently allow registers that are not architecturally
available to be present in the clobber list anymore, resulting in build failure
for mips*r6 targets in form of:
...
.../sysdep.h:146:2: error: the register ‘lo’ cannot be clobbered in ‘asm’ for the current target
  146 |  __asm__ volatile (	 \
      |  ^~~~~~~

This is because base R6 ISA doesn't define hi and lo registers w/o DSP extension.
This patch provides the alternative clobber list for r6 targets that won't include
those registers."

Since kernel 5.4 and mips support for generic vDSO [2], the kernel fails to build
for mips r6 cpus with gcc 10 for the same reason as glibc.

[1] https://sourceware.org/git/?p=glibc.git;a=commit;h=020b2a97bb15f807c0482f0faee2184ed05bcad8
[2] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=24640f233b466051ad3a5d2786d2951e43026c9d

Fixes:
https://gitlab.com/kubu93/buildroot/-/jobs/655618363
https://gitlab.com/kubu93/buildroot/-/jobs/655618364

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
2020-08-05 23:13:47 +02:00
..
patches/linux configs/qemu_mips64r6: fix Linux kernel build with gcc 10.x 2020-08-05 23:13:47 +02:00
linux.config qemu: update defconfigs to Linux 4.16.7 2018-06-02 22:23:39 +02:00
readme.txt board/qemu: remove the Qemu version from readme.txt 2020-04-26 13:44:21 +02:00

Run the emulation with:

 qemu-system-mips64 -M malta -cpu I6400 -kernel output/images/vmlinux -drive file=output/images/rootfs.ext2,format=raw -append "rootwait root=/dev/hda" -nographic # qemu_mips64r6_malta_defconfig

The login prompt will appear in the terminal that started Qemu.