Messages in this thread |  | | | Subject | Re: DMA transfer with kiobuf, kernel 2.4.21 | | From | Arjan van de Ven <> | | Date | Tue, 15 Nov 2005 19:01:53 +0100 |
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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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