linux-kernel - Re: [patch 3/5] x2apic, IR: cleanup panic() with nox2apic boot option

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Message-ID: <20090421070101.GB22937@elte.hu>
Date:	Tue, 21 Apr 2009 09:01:01 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Suresh Siddha <suresh.b.siddha@...el.com>
Cc:	hpa@...or.com, tglx@...utronix.de, linux-kernel@...r.kernel.org,
	dwmw2@...radead.org, Weidong Han <weidong.han@...el.com>
Subject: Re: [patch 3/5] x2apic, IR: cleanup panic() with nox2apic boot
	option


* Suresh Siddha <suresh.b.siddha@...el.com> wrote:

> Instead of panic() ignore the "nox2apic" boot option when BIOS has
> already enabled x2apic prior to OS handover.
> 
> Signed-off-by: Suresh Siddha <suresh.b.siddha@...el.com>
> Cc: Weidong Han <weidong.han@...el.com>
> ---
> 
> Index: tip/arch/x86/kernel/apic/apic.c
> ===================================================================
> --- tip.orig/arch/x86/kernel/apic/apic.c
> +++ tip/arch/x86/kernel/apic/apic.c
> @@ -142,8 +142,12 @@ static int x2apic_preenabled;
>  static int disable_x2apic;
>  static __init int setup_nox2apic(char *str)
>  {
> -	if (x2apic_enabled())
> -		panic("Bios already enabled x2apic, can't enforce nox2apic");
> +	if (x2apic_enabled()) {
> +		pr_warning("Bios already enabled x2apic, "
> +			   "can't enforce nox2apic");

Btw., in such cases we dont break printk strings in the middle but 
ignore the checkpatch warning. I fixed it up in your patch.

The advantage is that if someone, based on a dmesg line, types:

   git grep Bios already enabled x2apic, can't enforce nox2apic

the right source code line will be found. In the broken-up-line case 
this wont work. (grep is fundamentally single-line)

	Ingo
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