Re: User mode Virt -> Phys

Jamie Lokier (lkd@tantalophile.demon.co.uk)
Tue, 12 Jan 1999 14:37:08 +0000

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.

-- Jamie

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