Re: [libvirt] [Qemu-devel] [PATCH 2/2] target-i386: Haswell-noTSX and Broadwell-noTSX
On Mon, Mar 16, 2015 at 10:24:51AM +0000, Daniel P. Berrange wrote:
On Fri, Mar 13, 2015 at 04:09:57PM -0300, Eduardo Habkost wrote:
> With the Intel microcode update that removed HLE and RTM, there will be
> different kinds of Haswell and Broadwell CPUs out there: some that still
> have the HLE and RTM features, and some that don't have the HLE and RTM
> features. On both cases people may be willing to use the pc-*-2.3
> machine-types.
>
> So, to cover both cases, introduce Haswell-noTSX and Broadwell-noTSX CPU
> models, for hosts that have Haswell and Broadwell CPUs without TSX support.
>
> Signed-off-by: Eduardo Habkost <ehabkost(a)redhat.com>
The addition of Haswell-noTSX looks good to me.
I'm unclear on whether we truely need Broadwell-noTSX though. Did
Intel actually ship any Broadwell production silicon in which the
microcode disables this feature, or was it only a problem on
pre-production samples of Broadwell ? If the latter, I'd say we
don't need to have a Broadwell-noTSX model added. Perhaps Jun/Don
can confirm from Intel's side.
I've talked to Don and Jun, and they confirmed that a Broadwell-noTSX
CPU model will be needed, too.
I see some Broadwell CPUs without TSX-NI on ark.intel.com, too, so the
TSX errata wouldn't be the only reason for needing the -noTSX model.
--
Eduardo