Re: [Qemu-devel] [RFC v1 12/12] cpus: default MTTCG to on for 32 bit ARM on x86

[Peter Maydell]

On 6 June 2016 at 15:28, Alex Bennée <address@hidden> wrote:
> Peter Maydell <address@hidden> writes:
>> No new per-host ifdef ladders, please (or per-target ifdef ladders,
>> either). Have some #defines for "TCG backend supports MTTCG" and
>> "TCG frontend supports MTTCG" which get set in some suitable per-host
>> and per-target header, and only enable if they're both set.
>
> Will do so. I guess the middling case of backend is strongly ordered
> enough to get away with partial barrier implementation at the front end
> should be skipped?

I don't mind if you have multiple ifdefs for "backend fully supports
MTTCG" and "backend partially supports MTTCG" or whatever combination
makes sense -- I haven't looked enough at the implementation to
know what would be best. I just want to avoid ifdef ladders.

> Are you happy to keep the commentary here with the default function as
> that is where people are likely to end up when searching?

Yes, that makes sense. Consider also a section in tcg/README
documenting the requirements for a backend.

thanks
-- PMM