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Message-ID: <20110525090501.GA28500@elte.hu>
Date: Wed, 25 May 2011 11:05:01 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Borislav Petkov <bp@...en8.de>, Andi Kleen <andi@...stfloor.org>,
x86@...nel.org, linux-kernel@...r.kernel.org,
Andi Kleen <ak@...ux.intel.com>,
Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 1/3] x86, intel: Output microcode revision
* Borislav Petkov <bp@...en8.de> wrote:
> On Wed, May 25, 2011 at 08:54:51AM +0200, Ingo Molnar wrote:
> >
> > * Andi Kleen <andi@...stfloor.org> wrote:
> >
> > > From: Andi Kleen <ak@...ux.intel.com>
> > >
> > > I got a request to make it easier to determine the microcode update level
> > > on Intel CPUs. This patch adds a new "cpu update" field to /proc/cpuinfo,
> > > which I added at the end to minimize impact on parsers.
> >
> > Agreed, that is a good idea, adding this to cpuinfo makes sense.
>
> Frankly, I'm not even 100% persuaded this is needed. The coretemp.c
> jump-through-hoops to get the ucode revision is maybe the only case
> that warrants adding that field to /proc/cpuinfo.
I've often wondered whether the CPU involved in a particular
bugreport has the latest microcode installed.
Sure we have /sys/devices/system/cpu/cpuN/microcode/version, but
that's both privileged to get and also has to be asked for
separately.
Arguably the microcode version is a natural extension to the existing
family/model/stepping sequence:
cpu family : 6
model : 26
stepping : 5
We'd now see:
cpu family : 6
model : 26
stepping : 5
ucode_version : 17
Where 'stepping' is a hardware revison number and 'ucode_version' is
a dual software/hw revision number.
> > > @@ -111,6 +111,8 @@ struct cpuinfo_x86 {
> > > /* Index into per_cpu list: */
> > > u16 cpu_index;
> > > #endif
> > > + /* CPU update signature */
> > > + u32 x86_cpu_update;
> >
> > This should be cpu_microcode_version instead. We already know its x86 so the
> > x86_ prefix is superfluous. 'cpu_update' is also rather ambigious and does not
> > describe much.
>
> Or shorter: 'cpu_ucode_version'.
We already know it's a cpu data structure, since it's called 'struct
cpuinfo_x86' and the local variable is named 'c' which is the typical
shortcut for that data structure.
so c->ucode_version is the right name here.
Thanks,
Ingo
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