From: Ralf Baechle <ralf@oss.sgi.com>
To: Tom Appermont <tea@sonycom.com>
Cc: linux-mips@oss.sgi.com
Subject: Re: shared memory
Date: Wed, 29 Aug 2001 05:37:48 +0200 [thread overview]
Message-ID: <20010829053748.A16170@dea.linux-mips.net> (raw)
In-Reply-To: <20010828191725.A1221@sonycom.com>; from tea@sonycom.com on Tue, Aug 28, 2001 at 07:17:25PM +0200
On Tue, Aug 28, 2001 at 07:17:25PM +0200, Tom Appermont wrote:
> While this works as expected on PC, it does not at all work as
> expected on my mips platform (R5231): What is written in user
> space is not immediately visible in kernel space. This is with
> very recent kernel sources (2.4.8) but the same problem exists
> with an older (2.4.5) kernel.
>
> There have been a few mails about mmap() problems in the last
> couple of months, but with very little interesting response. Is
> this a known problem or am I stupidly overlooking something?
This is a different problem - and it's one caused by your code. You're
missing the necessary cache flushes in the kernel code. Using
_CACHE_UNCACHED is slow and breaks SMP.
Ralf
prev parent reply other threads:[~2001-08-29 3:41 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-08-28 17:17 shared memory Tom Appermont
2001-08-29 3:37 ` Ralf Baechle [this message]
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