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    SubjectRe: DMA transfer with kiobuf, kernel 2.4.21
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    On Tue, 2005-11-15 at 18:53 +0100, sej wrote:
    > > that sounds the wrong approach.. why don't you make your device driver
    > > export an mmap function.. and let the userspace app use that ?
    >
    > I can't because I need to allocate 128MB of memory per PCI card and if I put for example 4 cards, I'll have 512MB in kernel memory, and I think there will be some problem in kernel.

    no there isn't.. there is no rule that memory you allocate for this as
    to be lowmem... at all.

    >
    >
    >
    > >transfer->Descript[i].size = PAGE_SIZE;
    > >transfer->Descript[i].pciaddr = (ULONG)
    > >virt_to_phys(page_address(iobuf->maplist[idxIobuf]));
    > >
    > >
    >
    > > you really need to use the PCI DMA mapping api!
    >
    > I have a plx bridge PCI9656 with a DMA controler. So I have to make a
    > descriptor table with physical address and size.
    > I work in 32 bits address mode, but I don't know which function to call
    > to get a 36bits address for my controler.

    see the PCI DMA mapping api. the docs for it are in Documentation/



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