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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] Re: [PATCH 01/12] TCG "sync" op
Date: Mon, 16 Nov 2009 14:37:32 +0000
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To: Alexander Graf <agraf@suse.de>
Cc: riku.voipio@iki.fi, qemu-devel@nongnu.org, Aurelien Jarno <aurelien@aurel32.net>

> > While sync appears attractive as a quick hack to achieve this, I think it
> > is liable to be abused, and cause us serious pain long-term. If you need
> > an easy solution then use ld/st (as with ARM VFP registers). If you want
> > a good solution then fix whichever bit of TCG makes accessing a pair of
> > registers horribly slow. We already have some support for this
> > (concat_i32_i64).
> 
> Could we please include it nevertheless? I don't want to see S390 TCG
> and KVM targets not included because of this sync operation.
> 
> If you like, add some big fat warning around it and maybe break
> compilation if anyone but the s390 target uses that sync op, but let's
> not keep a whole target from inclusion because of a single feature that
> _might_ one day affect others.

I'd rather not include sync, and instead use the explicit ld/st code you 
already wrote.

Paul