linux-kernel - Re: [PATCH 6/8] SGI x86_64 UV: Limit the number of microcode messages

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Message-ID: <b647ffbd0910241545g4697a170peb00e541298d5a30@mail.gmail.com>
Date:	Sun, 25 Oct 2009 00:45:29 +0200
From:	Dmitry Adamushko <dmitry.adamushko@...il.com>
To:	Tigran Aivazian <tigran@...azian.fsnet.co.uk>
Cc:	Mike Travis <travis@....com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jack Steiner <steiner@....com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Andreas Mohr <andi@...as.de>, Hugh Dickins <hugh@...itas.com>,
	Hannes Eder <hannes@...neseder.net>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/8] SGI x86_64 UV: Limit the number of microcode messages

2009/10/24 Tigran Aivazian <tigran@...azian.fsnet.co.uk>:
> On Sat, 24 Oct 2009, Dmitry Adamushko wrote:
>>>
>>> -       printk(KERN_INFO "microcode: CPU%d sig=0x%x, pf=0x%x,
>>> revision=0x%x\n",
>>> +       if (cpu_num < 4 || !limit_console_output(false))
>>> +               printk(KERN_INFO
>>> +                       "microcode: CPU%d sig=0x%x, pf=0x%x,
>>> revision=0x%x\n",
>>>                        cpu_num, csig->sig, csig->pf, csig->rev);
>>>
>>
>> Hmm, I guess we wouldn't lose a lot by simply removing those messages
>> completely. Per-cpu pf/revision is available via /sys anyway.
>
> The reason for printing them is that the pf (possibly others?) can change by the update and so the log has this info handy.

We might store the old sig/pf/revision set as well, export them via
/sys or/and print them at update-to-new-microcode time.

If it's really so useful to have this info in the log and, at the same
time, to avoid the flood of messages (which, I guess for the majority
of systems, are the same) at startup time, we might delay the printout
until the end of microcode_init(). Then do something like this:

microcode cpu0: up to date version sig, pf, rev          // let's say,
it was updated by BIOS
microcode cpus [1 ... 16] : update from sig, pf, rev to sig, pf2, rev2.

Anyway, my humble opinion, is that (at the very least) the current
patch should be accompanied by a similar version for amd.


>
> Kind regards
> Tigran


-- Dmitry
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