From: "Michael S. Tsirkin" <mst@redhat.com> To: linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@linux-foundation.org> Cc: Davidlohr Bueso <dave@stgolabs.net>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, the arch/x86 maintainers <x86@kernel.org>, Davidlohr Bueso <dbueso@suse.de>, "H. Peter Anvin" <hpa@zytor.com>, virtualization <virtualization@lists.linux-foundation.org>, Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@redhat.com>, Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>, Andrey Konovalov <andreyknvl@google.com>, Borislav Petkov <bp@suse.de> Subject: [PATCH v3 2/4] x86: drop a comment left over from X86_OOSTORE Date: Wed, 13 Jan 2016 22:12:33 +0200 [thread overview] Message-ID: <1452715911-12067-3-git-send-email-mst@redhat.com> (raw) In-Reply-To: <1452715911-12067-1-git-send-email-mst@redhat.com> The comment about wmb being non-nop to deal with non-intel CPUs is a left over from before commit 09df7c4c8097 ("x86: Remove CONFIG_X86_OOSTORE"). It makes no sense now: in particular, wmb is not a nop even for regular intel CPUs because of weird use-cases e.g. dealing with WC memory. Drop this comment. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- arch/x86/include/asm/barrier.h | 4 ---- 1 file changed, 4 deletions(-) diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h index a65bdb1..a291745 100644 --- a/arch/x86/include/asm/barrier.h +++ b/arch/x86/include/asm/barrier.h @@ -11,10 +11,6 @@ */ #ifdef CONFIG_X86_32 -/* - * Some non-Intel clones support out of order store. wmb() ceases to be a - * nop for these. - */ #define mb() asm volatile(ALTERNATIVE("lock; addl $0,0(%%esp)", "mfence", \ X86_FEATURE_XMM2) ::: "memory", "cc") #define rmb() asm volatile(ALTERNATIVE("lock; addl $0,0(%%esp)", "lfence", \ -- MST
WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com> To: linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@linux-foundation.org> Cc: Davidlohr Bueso <dave@stgolabs.net>, Arnd Bergmann <arnd@arndb.de>, Davidlohr Bueso <dbueso@suse.de>, Peter Zijlstra <peterz@infradead.org>, Andrey Konovalov <andreyknvl@google.com>, the arch/x86 maintainers <x86@kernel.org>, virtualization <virtualization@lists.linux-foundation.org>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Borislav Petkov <bp@suse.de>, Andy Lutomirski <luto@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Ingo Molnar <mingo@kernel.org> Subject: [PATCH v3 2/4] x86: drop a comment left over from X86_OOSTORE Date: Wed, 13 Jan 2016 22:12:33 +0200 [thread overview] Message-ID: <1452715911-12067-3-git-send-email-mst@redhat.com> (raw) In-Reply-To: <1452715911-12067-1-git-send-email-mst@redhat.com> The comment about wmb being non-nop to deal with non-intel CPUs is a left over from before commit 09df7c4c8097 ("x86: Remove CONFIG_X86_OOSTORE"). It makes no sense now: in particular, wmb is not a nop even for regular intel CPUs because of weird use-cases e.g. dealing with WC memory. Drop this comment. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- arch/x86/include/asm/barrier.h | 4 ---- 1 file changed, 4 deletions(-) diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h index a65bdb1..a291745 100644 --- a/arch/x86/include/asm/barrier.h +++ b/arch/x86/include/asm/barrier.h @@ -11,10 +11,6 @@ */ #ifdef CONFIG_X86_32 -/* - * Some non-Intel clones support out of order store. wmb() ceases to be a - * nop for these. - */ #define mb() asm volatile(ALTERNATIVE("lock; addl $0,0(%%esp)", "mfence", \ X86_FEATURE_XMM2) ::: "memory", "cc") #define rmb() asm volatile(ALTERNATIVE("lock; addl $0,0(%%esp)", "lfence", \ -- MST
next prev parent reply other threads:[~2016-01-13 20:12 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-01-13 20:12 [PATCH v3 0/4] x86: faster mb()+documentation tweaks Michael S. Tsirkin 2016-01-13 20:12 ` [PATCH v3 1/4] x86: add cc clobber for addl Michael S. Tsirkin 2016-01-13 20:12 ` Michael S. Tsirkin 2016-01-13 20:12 ` Michael S. Tsirkin [this message] 2016-01-13 20:12 ` [PATCH v3 2/4] x86: drop a comment left over from X86_OOSTORE Michael S. Tsirkin 2016-01-13 20:12 ` [PATCH v3 3/4] x86: tweak the comment about use of wmb for IO Michael S. Tsirkin 2016-01-13 20:12 ` Michael S. Tsirkin 2016-01-13 20:12 ` [PATCH v3 4/4] x86: drop mfence in favor of lock+addl Michael S. Tsirkin 2016-01-13 20:12 ` Michael S. Tsirkin 2016-01-14 11:39 ` [PATCH v3 0/4] x86: faster mb()+documentation tweaks Borislav Petkov 2016-01-14 11:39 ` Borislav Petkov 2016-01-26 8:23 ` Michael S. Tsirkin 2016-01-26 8:23 ` Michael S. Tsirkin 2016-01-26 8:26 ` Boris Petkov 2016-01-26 8:26 ` Boris Petkov
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