powerpc/148003: commit references a PR

[dfilter service]

The following reply was made to PR powerpc/148003; it has been noted by GNATS.

From: dfilter at FreeBSD.ORG (dfilter service)
To: bug-followup at FreeBSD.org
Cc:  
Subject: Re: powerpc/148003: commit references a PR
Date: Sun, 20 Jun 2010 16:56:57 +0000 (UTC)

 Author: nwhitehorn
 Date: Sun Jun 20 16:56:48 2010
 New Revision: 209369
 URL: http://svn.freebsd.org/changeset/base/209369
 
 Log:
   Temporarily disable instruction relocation while setting up the kernel's
   IBAT entry in early boot in order to prevent possible faults from races
   between the instruction cache and the MMU.
   
   PR:		powerpc/148003
   MFC after:	3 days
 
 Modified:
   head/sys/powerpc/aim/mmu_oea.c
 
 Modified: head/sys/powerpc/aim/mmu_oea.c
 ==============================================================================
 --- head/sys/powerpc/aim/mmu_oea.c	Sun Jun 20 16:24:22 2010	(r209368)
 +++ head/sys/powerpc/aim/mmu_oea.c	Sun Jun 20 16:56:48 2010	(r209369)
 @@ -672,6 +672,7 @@ moea_bootstrap(mmu_t mmup, vm_offset_t k
  	vm_size_t	size, physsz, hwphyssz;
  	vm_offset_t	pa, va, off;
  	void		*dpcpu;
 +	register_t	msr;
  
          /*
           * Set up BAT0 to map the lowest 256 MB area
 @@ -702,12 +703,16 @@ moea_bootstrap(mmu_t mmup, vm_offset_t k
  
  	/*
  	 * Use an IBAT and a DBAT to map the bottom segment of memory
 -	 * where we are.
 +	 * where we are. Turn off instruction relocation temporarily
 +	 * to prevent faults while reprogramming the IBAT.
  	 */
 +	msr = mfmsr();
 +	mtmsr(msr & ~PSL_IR);
  	__asm (".balign 32; \n"
  	       "mtibatu 0,%0; mtibatl 0,%1; isync; \n"
  	       "mtdbatu 0,%0; mtdbatl 0,%1; isync"
  	    :: "r"(battable[0].batu), "r"(battable[0].batl));
 +	mtmsr(msr);
  
  	/* map pci space */
  	__asm __volatile("mtdbatu 1,%0" :: "r"(battable[8].batu));
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