Re: map_user_kiobuf question

Douglas Gilbert (dgilbert@interlog.com)
Fri, 05 Nov 1999 22:30:27 -0500

> What type of address gets passed to the third argument of
> map_user_kiobuf?
>
> can I do something like
>
> addr = vmalloc (size);
> ...
> map_user_kiobuf (xxx, iobuf, (unsigned long) addr, xxx);
> [ ... mess around with iobuf'd pages ... ]
> unmap_kiobuf (iobuf);

An address from the user space. For example the 2nd argument of
a read() [both the user space system call and a character device
read]. Not sure about the vmalloc() aspect.

Just to save you a little time, you may be needing the
recently added page_address() macro as well to get a 32 bit
address back out of a page object suitable for a DMA chip.

Doug Gilbert

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