Messages in this thread | | | Subject | Re: DMA transfer with kiobuf, kernel 2.4.21 | From | Arjan van de Ven <> | Date | Tue, 15 Nov 2005 18:49:45 +0100 |
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On Tue, 2005-11-15 at 18:39 +0100, sej wrote: > Hi, > I allocate a big chunck of memory from user space with : > > #define MEM_SIZE_DMA (128*1024*1024) > // allocate 128MB of memory > void *_pVirtualMem = memalign(sysconf(_SC_PAGESIZE), MEM_SIZE_DMA); > > // Reserve memory > memset(_pVirtualMem, 0, MEM_SIZE_DMA); > > // Lock memory > if (!mlock(_pVirtualMem, MEM_SIZE_DMA )) > { > free(_pVirtualMem); > return false; > } > > Then I call an IOCTL from my driver (DmaMapDescrpImg) to create a DMA > scatter gather list.
that sounds the wrong approach.. why don't you make your device driver export an mmap function.. and let the userspace app use that ?
> > 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!
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