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Message-ID: <20091029090957.GD22963@elte.hu>
Date: Thu, 29 Oct 2009 10:09:57 +0100
From: Ingo Molnar <mingo@...e.hu>
To: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
Cc: Roland Dreier <rdreier@...co.com>, linux-kernel@...r.kernel.org,
x86@...nel.org, Andi Kleen <ak@...ux.intel.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Mike Travis <travis@....com>
Subject: Re: [PATCH] x86, mce: short output of MCE banks ownership
information
* Hidetoshi Seto <seto.hidetoshi@...fujitsu.com> wrote:
> Ingo Molnar wrote:
> > * Hidetoshi Seto <seto.hidetoshi@...fujitsu.com> wrote:
> >> Maybe there would be more desirable ways, but I think that "compress
> >> messages shorter to bear heavy repeating" will be a good way at this
> >> time.
> >
> > We really want to only print out relevant information. 128 lines of
> > identical output is not relevant. (or 2x 64 lines, or 4096 lines of
> > identical output)
> >
> > So we only want to print MCE setup messages on the boot CPU. That gives
> > us 90% of the benefits already: we see the rough structure of the
> > hardware, and if the bootup has a problem with MCE initialization we get
> > relevant printouts that helps debugging.
> >
> > Now, it's certainly true that with things like MCE bank sharing the MCE
> > setup output from different CPUs might not be identical all the time -
> > but the information is represented in other (topology) info anyway. (and
> > if not it wasnt all that important to begin with)
> >
> > For non-boot CPUs we can perhaps add a mce=verbose (default-disabled)
> > mode of bootup that allows all CPUs to be printed - should there be any
> > problem with MCE details only visible on non-boot CPUs. (unlikely)
>
> How about having a kind of "boot=quiet_ap" which suppress boot-time
> messages for all non-boot CPUs, rather than "mce=verbose" which only
> suppress one (or, with thermal message, two) line? I don't not
> understand why this problem would be solved only by removing the lines
> from mce subsystem.
The idea is to suppress bootup messages by default - and to allow opt-in
verbose printing, in the (rare) case of having to debug bootup problems
that involve APs.
Ingo
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