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Re: ZONE_DMA on MIPS

To: ralf@linux-mips.org
Subject: Re: ZONE_DMA on MIPS
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Tue, 20 Mar 2007 01:36:08 +0900 (JST)
Cc: linux-mips@linux-mips.org
In-reply-to: <20070319154821.GA31766@linux-mips.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20070320.000947.88474417.anemo@mba.ocn.ne.jp> <20070319154821.GA31766@linux-mips.org>
Sender: linux-mips-bounce@linux-mips.org
On Mon, 19 Mar 2007 15:48:21 +0000, Ralf Baechle <ralf@linux-mips.org> wrote:
> > Are there any other platforms requires special DMA zone?
> 
> Qemu supports more or less the full PC braind^Wheritage, including the
> good old too-old floppy controller.  IP22 supports Indigo 2 systems
> which have EISA support, so we only want ZONE_DMA if EISA is enabled.
> For a bunch of other systems ZONE_DMA may be required to support b0rked
> PCI cards that only support like 31-bit DMA addresses or even less.

Hmm... So do you think making ZONE_DMA customizable for each platform
(or user configurable) would have some sense?

For these legacy(?) PCI cards, we can check if it works or not by
pci_set_dma_mask(), at least.

---
Atsushi Nemoto

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