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Re: [Qemu-devel] aarch32 acquire/release vs mttcg


From: Alex Bennée
Subject: Re: [Qemu-devel] aarch32 acquire/release vs mttcg
Date: Tue, 06 Nov 2018 14:23:25 +0000
User-agent: mu4e 1.1.0; emacs 26.1.50

Peter Maydell <address@hidden> writes:

> Looking through code I noticed that in target/arm/translate.c there
> is the following comment in the decode for the load-acquire/store-release
> instructions:
>
>       /* Since the emulation does not have barriers,
>          the acquire/release semantics need no special
>          handling */
>
> This is out of date now we have MTTCG, isn't it?

Yes

> The equivalent code in translate-a64.c has some calls to tcg_gen_mb()
> to emit barriers...presumably we need to fix the a32 code to do
> the same.

Sounds right. Are they the same semantics as their bigger 64 bit
cousins?

>
> (We haven't noticed this because I think in practice nobody
> much is compiling Armv8-specific AArch32 code.)
>
> thanks
> -- PMM


--
Alex Bennée



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