Re: DMA transfer with kiobuf, kernel 2.4.21

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi,
thank you for your help.
I will read the DMA documentation. But I need to make DMA on User memory space allocated in user space. Because I don't want the kernel to make allocation and deallocation during execution for stability.
Best regards.
Sebastien


Arjan van de Ven wrote :

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/



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux