From: Laurent Vivier <laurent@vivier.eu>
To: Paolo Bonzini <pbonzini@redhat.com>,
Aurelien Jarno <aurelien@aurel32.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
qemu-devel@nongnu.org, Richard Henderson <rth@twiddle.net>
Subject: Re: [Qemu-devel] [PATCH] target-sh4: add atomic tas
Date: Thu, 3 Nov 2016 14:32:10 +0100 [thread overview]
Message-ID: <3e5a59f3-e084-b772-b36e-041505053c7f@vivier.eu> (raw)
In-Reply-To: <2906e69f-b54d-aaa4-c728-c1c750eb1072@redhat.com>
Le 03/11/2016 à 14:29, Paolo Bonzini a écrit :
>
>
> On 03/11/2016 14:12, Laurent Vivier wrote:
>> Implement real atomic tas.
>>
>> As tas is:
>>
>> When (Rn) = 0, 1 -> T
>> Otherwise, 0 -> T
>> In both cases, 1 -> MSB of (Rn)
>>
>> It can't be implemented using cmpxchg().
>
> Why not?
Only because I don't know :)
> This is essentially
>
> movi temp0, 0x80
> atomic_fetch_or_i32 temp1, Rn, temp0, ctx->memidx, MO_UB
> setcondi_i32 cpu_sr_t, TCG_COND_EQ, temp1, 0
>
> But the patch looks good anyway.
I'm going to rewrite it as you say...
Thanks,
Laurent
prev parent reply other threads:[~2016-11-03 13:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-03 13:12 [Qemu-devel] [PATCH] target-sh4: add atomic tas Laurent Vivier
2016-11-03 13:29 ` Paolo Bonzini
2016-11-03 13:32 ` Laurent Vivier [this message]
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