linux-kernel - [PATCH] [3/7] Don't disable RDTSC in userland for 32bit notsc

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Message-Id: <20080118172719.76B7C14AAE@wotan.suse.de>
Date:	Fri, 18 Jan 2008 18:27:19 +0100 (CET)
From:	Andi Kleen <ak@...e.de>
To:	mingo@...e.hu, hpa@...or.com, tglx@...utronix.de,
	linux-kernel@...r.kernel.org
Subject: [PATCH] [3/7] Don't disable RDTSC in userland for 32bit notsc


Modern 32bit userland doesn't even boot when the TSC is disabled
because ld.so tends to contain RDTSCs.  So make notsc only effective for the 
kernel, similar to 64bit.
Signed-off-by: Andi Kleen <ak@...e.de>

---
 arch/x86/kernel/cpu/common.c |    1 -
 1 file changed, 1 deletion(-)

Index: linux/arch/x86/kernel/cpu/common.c
===================================================================
--- linux.orig/arch/x86/kernel/cpu/common.c
+++ linux/arch/x86/kernel/cpu/common.c
@@ -654,7 +654,6 @@ void __cpuinit cpu_init(void)
 		printk(KERN_NOTICE "Disabling TSC...\n");
 		/**** FIX-HPA: DOES THIS REALLY BELONG HERE? ****/
 		clear_bit(X86_FEATURE_TSC, boot_cpu_data.x86_capability);
-		set_in_cr4(X86_CR4_TSD);
 	}
 
 	load_idt(&idt_descr);
--
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