Re: [PULL 11/24] tcg/optimize: Use tcg_constant_internal with constant folding

[David Hildenbrand]

> Am 04.02.2021 um 03:22 schrieb Richard Henderson 
> <richard.henderson@linaro.org>:
> 
> On 2/1/21 10:45 AM, Richard W.M. Jones wrote:
>> This commit breaks running certain s390x binaries, at least
>> the "mount" command (or a library it uses) breaks.
>> 
>> More details in this BZ:
>> 
>> https://bugzilla.redhat.com/show_bug.cgi?id=1922248
>> 
>> Could we revert this change since it seems to have caused other
>> problems as well?
> 
> Well, the other problems have been fixed (which were in fact latent, and could
> have been produced by other means).  I would not like to sideline this patch
> set indefinitely.
> 
> Could you give me some help extracting the relevant binaries?  "Begin with an
> s390x host" is a non-starter.
> 

Hi,

I‘m planning on reproducing it today or tomorrow. Especially, finding a 
reproducer and trying reproducing on x86-64 host.

> FWIW, with qemu-system-s390x, booting debian, building qemu-s390x, and running
> "/bin/mount -t proc proc /mnt" under double-emulation does not show the bug.
> 
> I suspect that's because debian targets a relatively old s390x cpu, and that
> yours is using the relatively new vector instructions.  But I don't know.
> 
> What I do know is that current qemu doesn't seem to boot current fedora:
> 
> $ ../bld/qemu-system-s390x -nographic -m 4G -cpu max -drive
> file=Fedora-Server-netinst-s390x-33-1.2.iso,format=raw,if=virtio
> qemu-system-s390x: warning: 'msa5-base' requires 'kimd-sha-512'.
> qemu-system-s390x: warning: 'msa5-base' requires 'klmd-sha-512'.
> LOADPARM=[        ]
> Using virtio-blk.
> ISO boot image size verified
> 
> KASLR disabled: CPU has no PRNG
> Linux version 5.8.15-301.fc33.s390x
> (mockbuild@buildvm-s390x-07.s390.fedoraproject.org) 1 SMP Thu Oct 15 15:55:57
> UTC 2020Kernel fault: interruption code 0005 ilc:2
> PSW : 0000200180000000 00000000000124c4
>       R:0 T:0 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:0 CC:2 PM:0 RI:0 EA:3
> GPRS: 0000000000000000 0000000b806a2da6 7aa19c5cbb980703 95f62d65812b83ab
>       d5e42882af203615 0000000b806a2da0 0000000000000000 0000000000000000
>       00000000000230e8 0000000001438500 0000000001720320 0000000000000000
>       0000000001442718 0000000000010070 0000000000012482 000000000000bf20
> 
> Which makes me thing that fedora 33 is now targeting a cpu that is too new and
> not actually supported by tcg.
> 

Try rawhide instead, that worked when testing the clang build fixes. 
Alternatively, boot F33 via kernel and initrd.

The Fedora 33 iso is broken and cannot boot under KVM as well (the combined 
kernel+initrd file is messed up).

Cheers!

> 
> r~
>