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From: Andi Kleen <ak@suse.de>
To: davej@codemonkey.org.uk, mingo@elte.hu, tglx@linutronix.de,
	jesse.barnes@intel.com, andreas.herrmann3@amd.com,
	linux-kernel@vger.kernel.org
Subject: [PATCH] [1/2] Fix some inaccurate comments in MTRR checking code
Date: Sat, 19 Jan 2008 05:32:18 +0100 (CET)	[thread overview]
Message-ID: <20080119532.133547000@suse.de> (raw)


- is_cpu(INTEL) actually refers only to the MTRR architecture
and all AMD CPUs since K7 use the Intel MTRR architecture so the
fixup code runs on AMD too. Remove a comment claiming otherwise.

[Perhaps is_cpu should be renamed, the name is clearly confusing]

- Clarify another incorrect comment.

Cc: davej@codemonkey.org.uk
Signed-off-by: Andi Kleen <ak@suse.de>

---
 arch/x86/kernel/cpu/mtrr/main.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux/arch/x86/kernel/cpu/mtrr/main.c
===================================================================
--- linux.orig/arch/x86/kernel/cpu/mtrr/main.c
+++ linux/arch/x86/kernel/cpu/mtrr/main.c
@@ -640,6 +640,8 @@ early_param("disable_mtrr_trim", disable
  * Some buggy BIOSes don't setup the MTRRs properly for systems with certain
  * memory configurations.  This routine checks to make sure the MTRRs having
  * a write back type cover all of the memory the kernel is intending to use.
+ * [AK: actually it doesn't check that. It just checks that the highest
+ * MTRR is matching the end of memory. That is not quite the same.]
  * If not, it'll trim any memory off the end by adjusting end_pfn, removing
  * it from the kernel's allocation pools, warning the user with an obnoxious
  * message.
@@ -649,7 +651,6 @@ void __init mtrr_trim_uncached_memory(vo
 	unsigned long i, base, size, highest_addr = 0, def, dummy;
 	mtrr_type type;
 
-	/* Make sure we only trim uncachable memory on Intel machines */
 	rdmsr(MTRRdefType_MSR, def, dummy);
 	def &= 0xff;
 	if (!is_cpu(INTEL) || disable_mtrr_trim || def != MTRR_TYPE_UNCACHABLE)

             reply	other threads:[~2008-01-19  4:32 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-19  4:32 Andi Kleen [this message]
2008-01-19  4:32 ` [PATCH] [2/2] Fix MTRR check on AMD systems with > 4GB RAM Andi Kleen

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