Re: User mode Virt -> Phys

Mike A. Harris (mharris@ican.net)
Wed, 13 Jan 1999 03:56:21 -0500 (EST)

On Tue, 12 Jan 1999, Jamie Lokier 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.

Gee. DMA from userland? Might as well have userland run in ring
0 then... unless this is a special case, and not a general
kernel option suggestion. If someone is going to compromize
their system like that, they might as well use MSDOS IMHO.

--
Mike A. Harris  -  Computer Consultant  -  Linux advocate


Linux software galore:  http://freshmeat.net




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