From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: David Miller <davem@davemloft.net>
Cc: mingo@elte.hu, jamie.iles@picochip.com,
linux-kernel@vger.kernel.org, peterz@infradead.org
Subject: Re: [PATCH 1/2] perf tools: allow building for ARM
Date: Fri, 11 Dec 2009 21:19:23 +0000 [thread overview]
Message-ID: <20091211211923.GC12628@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20091211.023808.233094506.davem@davemloft.net>
On Fri, Dec 11, 2009 at 02:38:08AM -0800, David Miller wrote:
> From: Ingo Molnar <mingo@elte.hu>
> Date: Fri, 11 Dec 2009 11:23:16 +0100
>
> >
> > * Jamie Iles <jamie.iles@picochip.com> wrote:
> >
> >> +#ifdef __arm__
> >> +#include "../../arch/arm/include/asm/unistd.h"
> >> +#define rmb() asm volatile("":::"memory")
> >> +#define cpu_relax() asm volatile("":::"memory")
> >> +#endif
> >
> > cpu_relax() looks fine, but rmb() seems not to match the one that can be
> > found in arch/arm/:
>
> I think he did it this way so it can compile in the meantime,
> and that doing it right requires runtime cpu detection to
> select which barrier instruction is even available on the
> current ARM cpu.
We provide a way for userspace to be independent of the CPU for these
operations by providing code snippets up in the vector page for userspace
to call. The kernel places the correct code there according to the CPU
it's built for.
Look for __kuser_memory_barrier in arch/arm/kernel/entry-armv.S
prev parent reply other threads:[~2009-12-11 21:19 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-11 9:20 [PATCH 1/2] perf tools: allow building for ARM Jamie Iles
2009-12-11 9:21 ` [PATCH 2/2] perf tools: allow cross compiling Jamie Iles
2009-12-11 10:27 ` [tip:perf/urgent] perf tools: Allow " tip-bot for Jamie Iles
2009-12-11 12:20 ` [PATCH] perf tools: allow building for ARM (patch v2) Jamie Iles
2009-12-11 12:54 ` [tip:perf/urgent] perf tools: Allow building for ARM tip-bot for Jamie Iles
2009-12-11 13:04 ` Jamie Iles
2009-12-11 13:26 ` Ingo Molnar
2009-12-11 10:23 ` [PATCH 1/2] perf tools: allow " Ingo Molnar
2009-12-11 10:30 ` Jamie Iles
2009-12-11 10:38 ` Ingo Molnar
2009-12-11 11:01 ` Jamie Iles
2009-12-11 11:26 ` Mikael Pettersson
2009-12-11 21:22 ` Russell King - ARM Linux
[not found] ` <000101ca7a50$b3e2ad70$1ba80850$@deacon@arm.com>
2009-12-11 11:02 ` Ingo Molnar
2009-12-11 11:08 ` Pekka Enberg
2009-12-11 10:38 ` David Miller
2009-12-11 10:41 ` Ingo Molnar
2009-12-11 11:48 ` Jamie Iles
2009-12-11 12:48 ` Ingo Molnar
2009-12-11 21:19 ` Russell King - ARM Linux [this message]
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