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    SubjectRe: SCSI tape buffer allocation hitting memory allocation
    On Fri, 12 Feb 1999, Simon Kirby wrote:

    > Hmm...it makes obvious sense that some sort of transfer from a device to
    > physical memory wouldn't be able to go through the page translation on the
    > CPU unless the CPU was doing the transfer, so it makes sense that
    > vmalloc()ed pages wouldn't work. I wonder what the floppy driver does,
    > then...

    Okay, now that I've realized my first idea is really dumb, I'd like to
    confirm that DMA to an onboard/PCI device does actually work addressing
    physical memory > 64MB. Is this true? I changed scsi_init_malloc() to
    remove the GFP_DMA flag iff the first allocation w/GFP_DMA fails...it
    seems to now work (but obviously it will blow up for ISA cards). Is
    GFP_DMA is used anywhere else other than to tell __get_free_pages() to
    only allocate in areas < 64MB)? I'm assuming this should be safe (for the
    case of this one machine w/no ISA SCSI controllers) if not.

    Simon-

    | Simon Kirby | Systems Administration |
    | mailto:sim@netnation.com | NetNation Communications |
    | http://www.netnation.com/ | Tech: (604) 684-6892 |


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