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

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Date:	Wed, 4 Mar 2009 22:06:43 +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:

> Ingo Molnar wrote:
> > * 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().
> > 
> 
> will check that.
> 
> another solution is change smp_read_mpc interface, let it pass 
> mpf->physptr directly.

ok. Please pick the cleaner variant.

	Ingo
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