Messages in this thread | | | Date | Sun, 28 Mar 2004 20:54:10 +0200 | From | Pavel Machek <> | Subject | Re: Kernel support for peer-to-peer protection models... |
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Hi!
> > I meant "User Mode Linux" == linux running under linux. Someone > > probably has an URL. > > Sorry - I plead ignorance :-) As the protection is recursive and > transitive, I suppose that you could do this. When the UMK (user mode > kernel) went to change the "real" machine it would get a protection fault > that would be handled by the KMK, emulating the effect. Getting it right and > also performant would be tricky though - is UML a necessary feature?
No. Its just "nice to have", and it does not support too many architectures.
> > Strange system.... If an application does not grant kernel access to > > its space, how is kernel supposed to do its job? For example, that > > "paranoid DLL" becomes unswappable, then? > > Pretection is in the *virtual* space, not physical. The physical-page > manager (who has the TLB and underlying mapping tables in its space) can see > and deal with any physical address, which in turn has the usual aliasing > relationship with virtual addresses. Of course, physical is just one of the > virtual spaces (and is distinguished solely by the one-to-one > virtual-physical mapping). So the protection can be penetrated by anyone who > can see the underlying physical page - but that's always true.
Aha, so some part of kernel exist that has "absolute right". Ok, now I can imagine that it can work.
> > If most changes are in arch/, it should be acceptable... > > I fear that it might be more extensive than that :-)
Well, make patch and lets see... That means that 2.8 needs to be your target. If impact outside of arch is not "total rewrite", you might have a chance. If it is "total rewrite".... well you just need to be very clever. Pavel -- When do you have a heart between your knees? [Johanka's followup: and *two* hearts?] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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