Messages in this thread | | | Date | Fri, 28 Feb 2003 20:27:21 +0300 | From | Ivan Kokshaysky <> | Subject | Re: Proposal: Eliminate GFP_DMA |
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On Fri, Feb 28, 2003 at 04:05:50PM +0000, Russell King wrote: > Umm, question - I've seen ISA bridges with the ability to perform 32-bit > DMA using the ISA DMA controllers. AFAIK, Linux doesn't make use of this > feature, except on ARM PCI systems with ISA bridges.
Alpha uses this from day 1, BTW. Also, in 2.5 we have "isa_bridge" stuff which was intended exactly for that - it's a pointer to pci device (real ISA bridge with appropriate dma_mask) that can be used by non-busmastering ISA devices as a pci_dev * arg to pci_* mapping functions.
> Is there a reason > why this isn't used on x86 hardware?
Given a huge number of various ISA bridges found in x86 systems, I don't see a generic way to determine which ones can do 32-bit DMA... Maybe kind of white list?
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