[Bug target/121432] [15/16 regression] GCC has a regression on Microblaze since r15-1619-g3b9b8d6cfdf593

[neal.frager at amd dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121432

--- Comment #23 from Neal Frager <neal.frager at amd dot com> ---
(In reply to Gopi Kumar Bulusu from comment #22)
> OK, when a kernel is built using buildroot without that patch, it seems to
> work fine. However kernel does not boot when the patch is applied.
> 
> Needs more analysis. Stay tuned.

When you test with buildroot, you need to do the following.

1. Remove the gcc 15.2.0 patch that buildroot is currently using to work around
the problem:

https://gitlab.com/buildroot.org/buildroot/-/blob/master/package/gcc/15.2.0/0003-gcc-config-microblaze-fix-ira-for-GCC15.patch

2. Add the following config to either configs/qemu_microblazeel_mmu_defconfig
or configs/qemu_microblazebe_mmu_defconfig to use gcc 15.2.0 and not 14.3.0. 
The reported issue only appears when using gcc 15.

BR2_GCC_VERSION_15_X=y

After you have done this, you can modify the entry.S source file directly and
keep rebuilding new Linux kernel images until you have a solution that works.

Best regards,
Neal Frager
AMD