Re: [Qemu-devel] Impractical ideas?

[Jason Gress <jasong@ccgr.org>]

On Thursday 06 May 2004 05:11 pm, John R. Hogerhuis wrote:
> Of course, there is already something in real life that can get you most
> of this if you can afford to rent one: a logic analyzer with built-in
> disassembler.
>
> To buy one is *a lot* unless you get an old one like I have which is
> only useful mainly for instrumenting older systems.
>
> I guess we're getting really sci-fi now, but maybe you should just make
> it pass-through everything to underlying OS, and the front end would be
> a virtual logic analyzer.
>
> Of course thinking about the cool timing diagrams a logic analyzer gives
> you, I think I'm realizing what the real problem is here: timing.
> Virtual drivers incorporate knowledge of timing of the real devices in
> their operation.  Without that buffer between you and the bare metal, I
> think the live guest driver just ain't gonna work. Counterarguments?
>
I hate to feed the fire ;), but it would seem that drivers couldn't use too 
much timing information as they can never expect a certain time for anything.  
Example: If I had a 50MHz FSB, won't most PCI cards still work even though 
most systems run at 66MHz?  (Think old Pentiums)  Also I would think that in 
the case of, say a PCI Gigabit ethernet or HDD controller hogging the 
bandwidth on a PCI bus that a video card (or whatever) would still work 
properly even though the delays may go up on a 'real' system in those cases.  
So, in conclusion, I would think that timing may not be all 'that' 
important.  ;)

> -- John.
>
	Jason
>
>
>
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