Re: R200_NO_USLEEPS (was Re: [Dri-devel] R200 drivers on Sapphire 8500LE card report)

[Keith W. <ke...@tu...>]

Ingo Molnar wrote:
> On Fri, 30 Aug 2002, Keith Whitwell wrote:
> 
> 
>>I think the windows and closed-source drivers generally don't recognise
>>the security problems or don't care about them.
>>
>>The driver probably looks similar, but avoids the inspection/copying
>>step that we have to do - so that the userspace can just build command
>>buffers in agp space which are scheduled onto the ring perhaps by a
>>kernel module.
>>
> 
> hm, what are the wost-case security issues - can userspace cause the GX
> card to DMA into arbitrary RAM? 

Typically.

> Or only GX denial-of-service type of
> issues like monopolizing the GX card or interfering with other apps' GX
> ops?

That's pretty much impossible to stop.  Also hard lockups are typically 
possible even with streams of 'correct' commands -- cards can be incredibly 
sensitive about the oddest things and just hard lock the system if they get 
someting they don't like.  Maybe when we get to the point that we don't do 
this ourselves unintentionally we can start worrying about apps doing it 
intentionally...

Keith