linux-kernel - Re: [PATCH] x86: ioremap mptable

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Date:	Wed, 4 Mar 2009 20:50:14 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: ioremap mptable


* Yinghai Lu <yinghai@...nel.org> wrote:

> 
> Impact: fix boot with mptable above max_low_mapped
> 
> try to use early_ioremap to map mpc to make sure it works even it is
> at end of ram on system.
> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Reported-and-tested-by: Kevin O'Connor <kevin@...onnor.net>
> 
> ---
>  arch/x86/kernel/mpparse.c |   26 +++++++++++++++++++++++---
>  1 file changed, 23 insertions(+), 3 deletions(-)
> 
> Index: linux-2.6/arch/x86/kernel/mpparse.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/mpparse.c
> +++ linux-2.6/arch/x86/kernel/mpparse.c
> @@ -558,6 +558,19 @@ static inline void __init construct_defa
>  
>  static struct mpf_intel *mpf_found;
>  
> +static unsigned long __init get_mpc_size(unsigned long physptr)
> +{
> +	struct mpc_table *mpc;
> +	unsigned long size;
> +
> +	mpc = early_ioremap(physptr, PAGE_SIZE);
> +	size = mpc->length;
> +	early_iounmap(mpc, PAGE_SIZE);
> +	apic_printk(APIC_VERBOSE, "  mpc: %lx-%lx\n", physptr, physptr + size);
> +
> +	return size;
> +}
> +
>  /*
>   * Scan the memory blocks for an SMP configuration block.
>   */
> @@ -611,12 +624,16 @@ static void __init __get_smp_config(unsi
>  		construct_default_ISA_mptable(mpf->feature1);
>  
>  	} else if (mpf->physptr) {
> +		struct mpc_table *mpc;
> +		unsigned long size;
>  
> +		size = get_mpc_size(mpf->physptr);
> +		mpc = early_ioremap(mpf->physptr, size);
>  		/*
>  		 * Read the physical hardware table.  Anything here will
>  		 * override the defaults.
>  		 */
> -		if (!smp_read_mpc(phys_to_virt(mpf->physptr), early)) {
> +		if (!smp_read_mpc(mpc, early)) {
>  #ifdef CONFIG_X86_LOCAL_APIC
>  			smp_found_config = 0;
>  #endif
> @@ -624,8 +641,10 @@ static void __init __get_smp_config(unsi
>  			       "BIOS bug, MP table errors detected!...\n");
>  			printk(KERN_ERR "... disabling SMP support. "
>  			       "(tell your hw vendor)\n");
> +			early_iounmap(mpc, size);
>  			return;
>  		}
> +		early_iounmap(mpc, size);
>  
>  		if (early)
>  			return;

the whole "else if" branch here:

 	} else if (mpf->physptr) {

should move into a helper function, not just get_mpc_size().

	Ingo
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