Re: [PATCH] New phys_addr() syscall

Alan Cox (alan@lxorguk.ukuu.org.uk)
Tue, 21 Jul 1998 16:38:14 +0100 (BST)


> I was thinking of allowing the USB Stack to directly write to user
> pages using PCI. If PCI doesn't also honour the bits we need, could it
> be done by hand as the write is finished?

Ok firstly why do you need to write directly to user space - you would normally
want to buffer messages up anyway surely, in which case you are DMAing from
and to kernel space buffers. If you do need to do DMA directly you can instead
allocate a kernel buffer and let the user mmap() it as Hannu did with the sound
drivers and Ralph the bttv driver.

Alan

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