From: David Mosberger <davidm@napali.hpl.hp.com>
To: linux-ia64@vger.kernel.org
Subject: Re: [Linux-ia64] Modifing memory attributes needs cache flush
Date: Thu, 10 Jan 2002 19:17:51 +0000 [thread overview]
Message-ID: <marc-linux-ia64-105590698805792@msgid-missing> (raw)
In-Reply-To: <marc-linux-ia64-105590698805781@msgid-missing>
>>>>> On Wed, 09 Jan 2002 17:39:38 +0900 (JST), Takanori Kawano <t-kawano@ebina.hitachi.co.jp> said:
Takanori> If software modifies the memory attributes for a page,
Takanori> software must flush any processor cache copies with the
Takanori> Flush Cache(fc) instruction for the following memory
Takanori> attribute changes: speculative/non-speculative,
Takanori> cacheable/uncacheable(for transitions from cacheable to
Takanori> uncacheable), and coherency. Software must flush any
Takanori> coalescing buffers if a page is changes from coalescing to
Takanori> any other attribute.
Takanori> Does anybody know why the current code doesn't flush
Takanori> cache?
Well, the kernel is supposed to use each page in a consistent fashion
(no change of attributes). Though this isn't enforced anywhere (see
earlier discussion about write-coalescing mappings. We need a general
solution for this eventually. For now, it will have to be dealt with
on a case-by-case basis, I think.
--david
prev parent reply other threads:[~2002-01-10 19:17 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-09 8:39 [Linux-ia64] Modifing memory attributes needs cache flush Takanori Kawano
2002-01-10 19:17 ` David Mosberger [this message]
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