Re: [Qemu-devel] [PATCH 08/10] target-s390x: implement STFLE instruction

[Alexander Graf <agraf@suse.de>]

On 26.05.15 01:08, Richard Henderson wrote:
> On 05/24/2015 04:47 PM, Aurelien Jarno wrote:
>> Cc: Alexander Graf <agraf@suse.de>
>> Cc: Richard Henderson <rth@twiddle.net>
>> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
> 
> Sadly, implementing this breaks current kernels.
> I did this about two years ago and havn't figured
> out what to do about it.
> 
> The silly code in head.S doesn't check for just the
> facilities that it needs, it checks for all facilities
> that specific processors provide.
> 
> If we don't e.g. pretend that we have HFP, despite the
> fact that no one uses it, the kernel won't boot.

It depends on how the kernel is configured too. You can select the
minimum CPU type it can run on. But in most distros it's set to
something way beyond our current emulation scope.

But again, the real solution to this would be to have -cpu available and
have TCG available feature masks possible to get outed-out.


Alex