From: Greg Kurz <groug@kaod.org>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: qemu-ppc@nongnu.org,
Richard Henderson <richard.henderson@linaro.org>,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH 3/3] target/ppc: filter out non-zero PCR values when using TCG
Date: Fri, 15 Jun 2018 10:11:24 +0200 [thread overview]
Message-ID: <20180615101124.41862862@bahia.lan> (raw)
In-Reply-To: <20180615014501.GI4129@umbus.fritz.box>
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On Fri, 15 Jun 2018 11:45:01 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:
> On Fri, Jun 15, 2018 at 12:00:20AM +0200, Greg Kurz wrote:
> > 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 :)
>
> That is true, there are stub implementations of the TM instructions.
>
> >
> > > 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 :)
>
> That argument has come up before, and I disagree. I don't think it's
> reasonable to advertise TM support as available if the instructions
> always fail.
>
Fair enough! :)
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next prev parent reply other threads:[~2018-06-15 8:11 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-12 16:27 [Qemu-devel] [PATCH 1/3] target/ppc: drop empty #if/#endif block Greg Kurz
2018-06-12 16:43 ` Philippe Mathieu-Daudé
2018-06-12 17:01 ` [Qemu-devel] [PATCH 2/3] spapr: fix leak in h_client_architecture_support() Greg Kurz
2018-06-12 20:13 ` Philippe Mathieu-Daudé
2018-06-12 23:38 ` David Gibson
2018-06-12 17:04 ` [Qemu-devel] [PATCH 3/3] target/ppc: filter out non-zero PCR values when using TCG Greg Kurz
2018-06-13 0:45 ` David Gibson
2018-06-13 8:19 ` Greg Kurz
2018-06-13 12:05 ` David Gibson
2018-06-13 14:26 ` Greg Kurz
2018-06-14 1:26 ` David Gibson
2018-06-14 19:52 ` Richard Henderson
2018-06-14 22:00 ` Greg Kurz
2018-06-15 1:45 ` David Gibson
2018-06-15 3:38 ` Richard Henderson
2018-06-15 3:40 ` David Gibson
2018-06-15 8:11 ` Greg Kurz [this message]
2018-06-12 23:38 ` [Qemu-devel] [PATCH 1/3] target/ppc: drop empty #if/#endif block David Gibson
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