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From: Val Henson <val@nmt.edu>
To: benh@kernel.crashing.org
Cc: linux-kernel@vger.kernel.org
Subject: Re: Athlon/AGP issue update
Date: Fri, 25 Jan 2002 11:34:43 -0700	[thread overview]
Message-ID: <20020125113443.C26874@boardwalk> (raw)
In-Reply-To: <20020123.060855.26275529.davem@redhat.com> <20020123154737.19204@mailhost.mipsys.com>
In-Reply-To: <20020123154737.19204@mailhost.mipsys.com>; from benh@kernel.crashing.org on Wed, Jan 23, 2002 at 04:47:37PM +0100

On Wed, Jan 23, 2002 at 04:47:37PM +0100, benh@kernel.crashing.org wrote:
> >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).

Looking at bat_mapin_ram, it looks like we only map the first 512MB of
RAM with BATs, so we actually map the 512MB - 768MB range with PTEs
(and highmem starts at 768MB).  Two of the DBATs are used by I/O
mappings, so that only leaves two DBATs of 256MB each to map lowmem
anyway.  Am I missing something?

By the way, does the "nobats" option currently work on PowerMac?

-VAL

  reply	other threads:[~2002-01-25 18:35 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
2002-01-25 18:34         ` Val Henson [this message]
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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