Commit 0d7a1819 authored by Pavel Machek's avatar Pavel Machek Committed by Ingo Molnar
Browse files

x86: wmb() confusion in system.h



Comment says wmb is a nop, but it is implemented as lock addl
below... Should it be compiled to nop if we know we are running on
"good" Intel cpu?

At least remove confusing comment for now.
Signed-off-by: default avatarPavel Machek <pavel@suse.cz>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 3c2047cd
...@@ -296,16 +296,7 @@ void default_idle(void); ...@@ -296,16 +296,7 @@ void default_idle(void);
*/ */
#ifdef CONFIG_X86_32 #ifdef CONFIG_X86_32
/* /*
* For now, "wmb()" doesn't actually do anything, as all * Some non-Intel clones support out of order store. wmb() ceases to be a
* Intel CPU's follow what Intel calls a *Processor Order*,
* in which all writes are seen in the program order even
* outside the CPU.
*
* I expect future Intel CPU's to have a weaker ordering,
* but I'd also expect them to finally get their act together
* and add some real memory barriers if so.
*
* Some non intel clones support out of order store. wmb() ceases to be a
* nop for these. * nop for these.
*/ */
#define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2) #define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
......
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