From: Benjamin Herrenschmidt <benh@kernel•crashing.org>
To: Geoff Levand <geoffrey.levand@am•sony.com>
Cc: Olof Johansson <olof@lixom•net>, linuxppc-dev@ozlabs•org
Subject: Re: [RFC]: map 4K iommu pages even on 64K largepage systems.
Date: Tue, 24 Oct 2006 12:23:59 +1000 [thread overview]
Message-ID: <1161656640.10524.527.camel@localhost.localdomain> (raw)
In-Reply-To: <453D635B.20405@am.sony.com>
> This is a step in the right direction. Cell allows each device to
> have its own io pagesize, from among those that the io controller
> supports (4k, 64k, 1m,16m). This limitation of the current iommu
> code that you try to address here has caused me to use platform
> specific dma alloc routines.
Are devices -actually- using different page sizes ? AFAIK, for your
platform, you are using a 4k base page size, thus there is very little
point (in fact, it's more like a problem) to have an IO mapping using
larger page sizes.
In any case, read my reply to Linas, I'm proposing a scheme where each
iommu_table instance could have its own page size, in which case you can
just create a table instance per device.
Ben.
next prev parent reply other threads:[~2006-10-24 2:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-24 0:25 [RFC]: map 4K iommu pages even on 64K largepage systems Linas Vepstas
2006-10-24 0:50 ` Geoff Levand
2006-10-24 2:23 ` Benjamin Herrenschmidt [this message]
2006-10-24 2:22 ` Benjamin Herrenschmidt
2006-10-24 3:00 ` Geoff Levand
2006-10-24 4:43 ` Benjamin Herrenschmidt
2006-10-24 5:14 ` [PATCH] powerpc: " Benjamin Herrenschmidt
2006-10-24 20:08 ` Linas Vepstas
2006-10-24 21:41 ` Benjamin Herrenschmidt
2006-10-24 23:17 ` Linas Vepstas
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