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&gt; > > 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.