From: <benh@kernel.crashing.org>
To: "David S. Miller" <davem@redhat.com>
Cc: <drobbins@gentoo.org>, <linux-kernel@vger.kernel.org>,
<andrea@suse.de>, <alan@redhat.com>, <akpm@zip.com.au>,
<vherva@niksula.hut.fi>, <lwn@lwn.net>, <paulus@samba.org>
Subject: Re: Athlon/AGP issue update
Date: Wed, 23 Jan 2002 16:47:37 +0100 [thread overview]
Message-ID: <20020123154737.19204@mailhost.mipsys.com> (raw)
In-Reply-To: <20020123.060855.26275529.davem@redhat.com>
In-Reply-To: <20020123.060855.26275529.davem@redhat.com>
>I don't think your PPC case needs the kernel mappings messed with.
>I really doubt the PPC will speculatively fetch/store to a TLB
>missing address.... unless you guys have large TLB mappings on
>PPC too?
Yes, we use BATs (sort of built-in fixed large TLBs) to map
the lowmem (or entire RAM without CONFIG_HIGHMEM).
So if some kind of loop is fetching memory near the end of a non-AGP
page via the linear RAM mapping (BAT mapping) and the next page is an
AGP bound page, the CPU may do speculative access to the AGP page via
the BAT mapping thus bringing in a cache line for the AGP page.
At least, that's my understanding, it has to be validated by some
CPU gurus from IBM though.
Ben.
next prev parent reply other threads:[~2002-01-23 15:48 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-01-23 9:52 Athlon/AGP issue update Daniel Robbins
2002-01-23 10:18 ` David S. Miller
2002-01-23 2:46 ` benh
2002-01-23 14:08 ` David S. Miller
2002-01-23 15:47 ` benh [this message]
2002-01-25 18:34 ` Val Henson
2002-01-26 0:20 ` Benjamin Herrenschmidt
2002-01-27 19:22 ` Val Henson
2002-01-27 19:32 ` Benjamin Herrenschmidt
2002-01-23 16:31 ` Albert D. Cahalan
2002-01-23 16:57 ` Daniel Robbins
2002-01-23 17:14 ` benh
2002-01-23 23:14 ` Albert D. Cahalan
2002-01-25 18:17 ` Val Henson
2002-01-23 19:20 ` Oliver Neukum
[not found] ` <200201231010.g0NAAuE05886@Port.imtp.ilyichevsk.odessa.ua>
2002-01-23 10:24 ` David S. Miller
2002-01-23 10:31 ` Rik van Riel
2002-01-23 11:39 ` David S. Miller
2002-01-23 11:39 ` William Lee Irwin III
2002-01-23 11:47 ` David S. Miller
2002-01-23 17:09 ` Albert D. Cahalan
2002-01-23 18:38 ` David S. Miller
-- strict thread matches above, loose matches on Subject: below --
2002-01-23 10:38 Studierende der Universitaet des Saarlandes
2002-01-23 11:44 ` David S. Miller
2002-01-23 12:32 ` Momchil Velikov
2002-01-23 12:34 ` David S. Miller
2002-01-23 12:41 ` Momchil Velikov
2002-01-23 14:50 ` Manfred Spraul
2002-01-23 11:44 ` David Woodhouse
2002-01-23 11:49 ` David S. Miller
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