[patch, 2.6.22-rc6] fix nmi_watchdog=2 bootup hang, take #2

Ingo Molnar
2007-06-25T18:50:45Z

* Björn Steinbrink <B.Steinbrink@gmx.de> wrote:

> > and of course i'm happy to test any patch that is simpler than the
> > brutal revert i sent.
>
> wrmsrl() looks broken, dropping the upper 32bits of the value to be
> written. Does this help?

this did the trick, rc6 plus your fix and the NMI watchdog works again!
Thanks! I suspect other code (oprofile?) broke due to this too.

below is a tidied up patch for upstream application. Must-have for
2.6.22.

Ingo

----------------->
From: Björn Steinbrink <B.Steinbrink@gmx.de>
Subject: [patch, 2.6.22-rc6] fix nmi_watchdog=2 bootup hang, take #2

wrmsrl() is broken, dropping the upper 32bits of the value to be
written. This broke the NMI watchdog on AMD hardware. (and it
probably broke other code too.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/asm-i386/paravirt.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux/include/asm-i386/paravirt.h
===================================================================
--- linux.orig/include/asm-i386/paravirt.h
+++ linux/include/asm-i386/paravirt.h
@@ -539,7 +539,7 @@ static inline int paravirt_write_msr(uns
val = paravirt_read_msr(msr, &_err); \
} while(0)

-#define wrmsrl(msr,val) ((void)paravirt_write_msr(msr, val, 0))
+#define wrmsrl(msr,val) wrmsr(msr, (u32)((u64)(val)), ((u64)(val))>>32)
#define wrmsr_safe(msr,a,b) paravirt_write_msr(msr, a, b)

/* rdmsr with exception handling */