On Thursday 17 March 2005 17:49, Nicolas Boulay wrote:
> Le jeudi 17 Mars 2005 22:27, Attila Kinali a �crit :
> > [EMAIL PROTECTED] wrote:
> > > Proposal:
> > > Why don't you include a security register alongside the DMA
> > > registers. When the commands are DMAed in and proccessed any
> > > "priviliged" command encountered would either be turned into a no
> > > op or halt execution if the security register is set.
> >
> > This is IMHO a no-issue. No unprivileged user space programm
> > should be able to insert anything directly into the graphic card
> > w/o the interception of a driver. Any priviledge checking and
> > enforcing has to be done in software as 1) it is impossible to
> > forsee how future OS will handle priviledges and 2) to keep the
> > transistor count down.
>
> uh ? I beleive that user space lib should talk directly to the card
> to have the full speed.
Yes.
> A better idea is to split user/priviledge command into register bank
> in different 4k page boundary. That's cost nothing in hardware.
Furthermore, there may not be anything to split. I propose the
following:
- An unprivileged task can only submit commands via indirect DMA.
Each indirect DMA buffer is submitted by ioctling the kernel
- PIO is only available to privileged tasks, normally only the kernel
driver.
Clean and simple.
Regards,
Daniel
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