From: Arnd Bergmann <arnd@arndb.de>
To: cbe-oss-dev@ozlabs.org
Cc: Olof Johansson <olof@lixom.net>, linuxppc-dev@ozlabs.org
Subject: Re: [Cbe-oss-dev] [PATCH 3/3] Cell IOMMU static mapping support
Date: Mon, 28 Jan 2008 12:41:48 +0100 [thread overview]
Message-ID: <200801281241.49059.arnd@arndb.de> (raw)
In-Reply-To: <20080126025117.GA28066@lixom.net>
On Saturday 26 January 2008, Olof Johansson wrote:
> >
> > So instead of having an IOMMU window that we use to temporarily map things
> > in and out of DMA'able space, at boot we create a 1:1 mapping for all of
> > memory. This obviously only works for devices that can do 64-bit DMA.
>
> I don't get it. Why not disable the iommu instead?
>
When you disable the iommu, the 32-bit devices stop working because
they can no longer access all of main memory.
The 1:1 mapping is in addition to the DMA window used for those devices,
not in place of it.
Arnd <><
next prev parent reply other threads:[~2008-01-28 11:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-25 10:45 [PATCH 1/3] Add set_dma_ops() to match get_dma_ops() Michael Ellerman
2008-01-25 10:45 ` [PATCH 2/3] Allocate the hash table under 1G on cell Michael Ellerman
2008-02-05 0:23 ` Benjamin Herrenschmidt
2008-01-25 10:45 ` [PATCH 3/3] Cell IOMMU static mapping support Michael Ellerman
2008-01-25 13:12 ` [Cbe-oss-dev] " Geert Uytterhoeven
2008-01-26 2:51 ` Olof Johansson
2008-01-28 11:41 ` Arnd Bergmann [this message]
2008-01-28 16:23 ` [Cbe-oss-dev] " Olof Johansson
2008-01-28 21:16 ` Benjamin Herrenschmidt
2008-01-28 21:48 ` Olof Johansson
2008-01-28 21:37 ` Benjamin Herrenschmidt
2008-01-28 21:18 ` Benjamin Herrenschmidt
2008-02-05 0:23 ` [PATCH 1/3] Add set_dma_ops() to match get_dma_ops() Benjamin Herrenschmidt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=200801281241.49059.arnd@arndb.de \
--to=arnd@arndb.de \
--cc=cbe-oss-dev@ozlabs.org \
--cc=linuxppc-dev@ozlabs.org \
--cc=olof@lixom.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.