linux-kernel - [PATCH 8/8] x86/mrst: Add nop functions to x86

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Date:	Fri,  7 May 2010 10:41:48 -0700
From:	Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Alek Du <alek.du@...el.com>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Feng Tang <feng.tang@...el.com>,
	LKML <linux-kernel@...r.kernel.org>
Cc:	Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: [PATCH 8/8] x86/mrst: Add nop functions to x86_init mpparse functions

Moorestown does not have BIOS provided MP tables, we can save some time
by avoiding scaning of these tables. e.g.
[    0.000000] Scan SMP from c0000000 for 1024 bytes.
[    0.000000] Scan SMP from c009fc00 for 1024 bytes.
[    0.000000] Scan SMP from c00f0000 for 65536 bytes.
[    0.000000] Scan SMP from c00bfff0 for 1024 bytes.

Searching EBDA with the base at 0x40E will also result in random pointer
deferencing within 1MB. This can be a problem in Lincroft if the pointer
hits VGA area and VGA mode is not enabled.

Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
---
 arch/x86/kernel/mrst.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/mrst.c b/arch/x86/kernel/mrst.c
index 0b3ef9f..73c1692 100644
--- a/arch/x86/kernel/mrst.c
+++ b/arch/x86/kernel/mrst.c
@@ -351,5 +351,9 @@ void __init x86_mrst_early_setup(void)
 
 	legacy_pic = &null_legacy_pic;
 
+	/* Avoid searching for BIOS MP tables */
+	x86_init.mpparse.find_smp_config = x86_init_noop;
+	x86_init.mpparse.get_smp_config = x86_init_uint_noop;
+
 	mrst_identify_cpu();
 }
-- 
1.6.3.3

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