From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: sp@scali.no (Steffen Persvold)
Cc: helgehaf@idb.hist.no (Helge Hafting),
pvvvarma@techmas.hcltech.com (Vasu Varma P V),
linux-kernel@vger.kernel.org
Subject: Re: DMA memory limitation?
Date: Fri, 6 Jul 2001 12:08:51 +0100 (BST) [thread overview]
Message-ID: <E15ITTf-0004Dz-00@the-village.bc.nu> (raw)
In-Reply-To: <3B458888.75C50552@scali.no> from "Steffen Persvold" at Jul 06, 2001 11:44:40 AM
> A problem arises on 64 bit platforms (such as IA64) if your PCI card is only 32bit (can
> address the first 4G) and you don't wan't to use bounce buffers. If you use GFP_DMA on
GFP_DMA is ISA dma reachable, Forget the IA64, their setup is weird and
should best be ignored until 2.5 as and when they sort it out.
> bounce buffers are needed. On Alpha GFP_DMA is not limited at all (I think). Correct me if
Alpha has various IOMMU facilities
> I'm wrong, but I really think there should be a general way of allocating memory that is
> 32bit addressable (something like GFP_32BIT?) so you don't need a lot of #ifdef's in your
> code.
No ifdefs are needed
GFP_DMA - ISA dma reachable
pci_alloc_* and friends - PCI usable memory
next prev parent reply other threads:[~2001-07-06 11:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-07-05 11:47 DMA memory limitation? Vasu Varma P V
2001-07-05 11:53 ` Alan Cox
2001-07-05 11:54 ` Arjan van de Ven
2001-07-05 12:37 ` Vasu Varma P V
2001-07-05 12:37 ` Richard B. Johnson
2001-07-05 17:07 ` Christophe Beaumont
2001-07-05 17:19 ` Richard B. Johnson
2001-07-06 8:59 ` Helge Hafting
2001-07-06 9:44 ` Steffen Persvold
2001-07-06 11:08 ` Alan Cox [this message]
2001-07-06 11:27 ` Jeff Garzik
2001-07-06 15:16 ` Steffen Persvold
2001-07-06 15:39 ` Jeff Garzik
2001-07-06 15:48 ` Alan Cox
2001-07-06 15:56 Matt_Domsch
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