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Date: Fri, 15 Jun 2018 00:00:20 +0200
From: Greg Kurz <groug@kaod.org>
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Subject: Re: [Qemu-devel] [PATCH 3/3] target/ppc: filter out non-zero PCR
 values when using TCG
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To: Richard Henderson <richard.henderson@linaro.org>
Cc: David Gibson <david@gibson.dropbear.id.au>, qemu-ppc@nongnu.org, qemu-devel@nongnu.org

On Thu, 14 Jun 2018 09:52:55 -1000
Richard Henderson <richard.henderson@linaro.org> wrote:

> On 06/12/2018 10:19 PM, Greg Kurz wrote:
> > I'm confused... I don't see anything related to HTM in TCG. Also we have
> > the following in cap_htm_apply():
> > 
> >     if (tcg_enabled()) {
> >         error_setg(errp,
> >                    "No Transactional Memory support in TCG, try cap-htm=off");
> > 
> > I'm probably missing something... can you enlighten me ?  
> 
> One of the two IBM machines -- and I thought it was ppc not s390x, but the code
> you quote seems to deny that memory -- has stub support for TM within TCG.
> 

Oh ? I didn't know and didn't check :)

> To wit, the instructions are recognized and transactions always fail.  Which is
> not a bad way to test the required fallback paths that rarely fail on hardware.
>  ;-)

If TM instructions don't cause an exception, I guess its reasonable to say
they're supported :)

--
G

> 
> 
> r~