From: Linus Torvalds <torvalds@linux-foundation.org>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Luis R. Rodriguez" <mcgrof@gmail.com>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-kernel <linux-kernel@vger.kernel.org>,
Jeff Garzik <jeff@garzik.org>,
"John W. Linville" <linville@tuxdriver.com>,
linux-wireless <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH] Clarify pci_iomap() usage for MMIO-only devices
Date: Tue, 18 Sep 2007 15:36:23 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.0.999.0709181533370.16478@woody.linux-foundation.org> (raw)
In-Reply-To: <1190154117.6403.127.camel@localhost.localdomain>
On Wed, 19 Sep 2007, Benjamin Herrenschmidt wrote:
>
> Also, I've been told that modern x86 chipsets have the ability to remap
> IO space in the CPU physical address space. Is that true ? That would
> allow even x86 to get rid of the condition and just use some magic
> offset at map time.
I've not seen that, but I wouldn't be entirely surprised if IO
virtualization eventually causes something like this to happen:
virtualizing PIO is just damn painful right now, due to the lack of any
way to remap it.
I *think* you may be confused with the PCI config cycles, where the new
MMIO configuration was introduced (for similar virtualization reasons).
But it's also possible that this is one of those undocumented areas and
CPU's actually do have some IO remapping facility.
Linus
next prev parent reply other threads:[~2007-09-18 22:37 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-17 20:22 [PATCH] Clarify pci_iomap() usage for MMIO-only devices Luis R. Rodriguez
2007-09-18 10:34 ` Alan Cox
2007-09-18 18:46 ` Luis R. Rodriguez
2007-09-18 19:03 ` Linus Torvalds
2007-09-18 19:07 ` Luis R. Rodriguez
2007-09-18 19:22 ` Linus Torvalds
2007-09-18 20:12 ` Luis R. Rodriguez
2007-09-18 20:30 ` Linus Torvalds
2007-09-18 21:02 ` Luis R. Rodriguez
2007-09-18 21:14 ` Linus Torvalds
2007-09-18 21:30 ` Jeff Garzik
2007-09-18 21:42 ` Linus Torvalds
2007-09-18 22:25 ` Linus Torvalds
2007-09-18 22:21 ` Benjamin Herrenschmidt
2007-09-18 22:36 ` Linus Torvalds [this message]
2007-09-18 20:21 ` Jeff Garzik
2007-09-18 22:20 ` Benjamin Herrenschmidt
2007-09-18 23:08 ` Jeff Garzik
2007-09-18 23:27 ` Linus Torvalds
2007-09-18 22:16 ` Benjamin Herrenschmidt
2007-09-18 22:25 ` Alan Cox
2007-09-19 15:07 ` Nick Kossifidis
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