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Message-ID: <20140307222218.GB580@redhat.com>
Date: Fri, 7 Mar 2014 17:22:18 -0500
From: Dave Jones <davej@...hat.com>
To: "H. Peter Anvin" <hpa@...ux.intel.com>
Cc: Borislav Petkov <bp@...en8.de>,
Fengguang Wu <fengguang.wu@...el.com>,
Ingo Molnar <mingo@...nel.org>,
Yinghai Lu <yhlu.kernel@...il.com>,
LKML <linux-kernel@...r.kernel.org>,
Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [qemu64,+smep,+smap] WARNING: CPU: 1 PID: 0 at
arch/x86/kernel/cpu/amd.c:220 init_amd()
On Fri, Mar 07, 2014 at 02:11:50PM -0800, H. Peter Anvin wrote:
> > > * Another option would be if we change the f/m/s of "qemu64" so that
> > > the test doesn't fire.
> > >
> > > What also makes me wonder is why is this thing even called qemu64?? AMD
> > > family 6 was 32-bit only CPUs so 64 is kinda wrong IMO. I mean, the
> > > kernel code is in "ifdef CONFIG_X86_32" block so "qemu64" is patently
> > > wrong naming.
> >
> > Additionally, fam:6 model:6 stepping 3 never existed in the real world afaict.
> > I used to keep x86info's stepping db pretty up to date, and that only has knowledge
> > of stepping 1 & 2.[*] Modelling qemu on something from the real world might be
> > a better idea than inventing new special cases.
> >
> > > Oh, and the thing has CPUID_EXT2_LM which is also a WTH moment for me.
> > > Paolo, what's going on here?
> >
> > Yeah, this is a mess, there should be no family < 0xf with LM set.
> >
> For AMD, at least. Intel obviously have a bunch of chips with family ==
> 6 and LM.
Yeah, speaking solely about AMD here.
Dave
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