Re: Accessing copy_to_user() from interrupt handler?

Alan Cox (
Sat, 23 Nov 1996 01:16:34 +0000 (GMT)

> > Its 'entertaining'.
> What do you mean by entertaining (I can see you grinning while typing
> this...). Is there a fundamental reason why it wouldn't work?

Its very nasty (get the ATM release and read mmuio.c. But dont do it too
soon after lunch).

> What kind of kernel memory can you mmap() into user space?

Any of it

> kmalloc()'d? Has it to be GFP_DMA? vmalloc()'d? Static?

All of the above.

> The CCD has 768*516 pixels with 16 bit each (792.576 bytes). So
> kmalloc() doesn't cut it. If you want to mmap() something, it has to
> be continuous, right?

No. Your kernel driver can map arbitary pages into the map. If you want
you can have a /dev/kmembackwards device for example that maps the kernel
pages in reverse order.