On Thu, 2 Aug 2001, Julian Elischer wrote:
> On Thu, 2 Aug 2001, Rik van Riel wrote:
> >
> > On the really large machines, this can lead to the
> > situation where even the page tables hardly fit into
> > KVA. 4MB pages seem like the only solution ...
>
> There is no reason why we need to keep the kernel and the user
> process in the same 4GB map except for efficiency.
>
> There have been many UNIX machines in the past which put them in
> separate virtual spaces
That was on machines where the CPU could actually
address two separate spaces at once, right ?
(like eg. m68k)
> The kernel would haev 4GB for itself and each process would have 4BG.
>
> System calls would be come more expensive as each would require
> a full page-table swap and a TLB flush.
> However it might be worth it for some people.
Interrupt handling would also require a full page table
swap and TLB flush.
Considering that, I think the number of people for whom
this will be worth it has probably dropped a bit ;)
Rik
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