Re: User mode Virt -> Phys
Alan Cox (alan@lxorguk.ukuu.org.uk)
Tue, 12 Jan 1999 17:23:21 +0000 (GMT)
> On Tue, Jan 12, 1999 at 12:54:45AM +0000, Alan Cox wrote:
> > > The linux kernel is full of calls to virt_to_phys. This function seems
> > > only to work in kernel mode. Is there a way to convert a physical address
> > > to a virtual address in user mode (from a regular program)?
> >
> > No. Nor should there ever need to be.
>
> Yes, for user level I/O stuff doing PCI DMA. Not normal applications by
> any means, and you'd better know what you're doing.
>
> I have code which implements this quite cleanly (as this sort of thing
> goes), but I haven't released it yet and won't until I am ready.
You still don't need to do that translation for user space. Have a look
at Stephen Tweedie <sct@redhat.com>'s raw-io patches and DMA hooks in
kernel space for handling this stuff
Alan
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