linux-kernel - Re: [PATCH] x86: kill arch/x86/kernel/mpparse.c debugging printk.

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Message-ID: <48A05E79.4030304@keyaccess.nl>
Date:	Mon, 11 Aug 2008 17:44:57 +0200
From:	Rene Herman <rene.herman@...access.nl>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Andrew Morton <akpm@...l.org>, Yinghai Lu <yhlu.kernel@...il.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: kill arch/x86/kernel/mpparse.c debugging printk.

On 11-08-08 14:20, Ingo Molnar wrote:

>> From: Rene Herman <rene.herman@...access.nl>
>> Date: Thu, 7 Aug 2008 01:50:35 +0200
>> Subject: [PATCH] x86: kill arch/x86/kernel/mpparse.c debugging printk.
>>
>> commit 11a62a056093a7f25f1595fbd8bd5f93559572b6 turns some formerly 
>> nopped debugging printks in arch/x86/kernel/mppparse.c into regular 
>> ones. The one at the top of smp_scan_config() in particular also 
>> prints on !CONFIG_SMP/CONFIG_X86_LOCAL_APIC kernels and UP machines 
>> without anything resembling MP tables which makes their lowly UP 
>> owners wonder...
>>
>> given that it was up to this point also not considered valuable 
>> user-level information, let's just kill that one.
> 
> hm, i found it useful in the past in about 2-3 cases.
> 
> How about a patch that makes the printout depend on apic=debug ? That 
> way the message can still be there in case of bugreports that somehow 
> deal with SMP or APIC bugs (without having to recompile the kernel).
> 
> The way to make the printout depend on apic=debug/verbose is to do 
> something like this:
> 
> 	apic_printk(APIC_VERBOSE, "Scan SMP from %p for %ld bytes.\n", bp, length);
> 
> Would you mind to send a patch for that?

I wouldn't. Like this? This turns the printk's that used to be Dprintk's 
into apic_printk's.

I am myself only interested in the one at the top of smp_scan_config() 
(it made me think I had misconfigured something upon all of a sudden 
seeing SMP printk's on my UP machine on 2.6.27-rc) but I guess this is 
the more complete version.

One problem; on 32-bit, "apic=" is a __setup() param and isn't actually 
early enough for us here so this needs it turned into an early_param() 
(followup).

Rene.

View attachment "0001-x86-make-arch-x86-kernel-mpparse.c-debugging-printk.patch" of type "text/plain" (3251 bytes)