Kernel Virtual Address Space

[Julian Elischer]

On Tue, 3 Feb 2004, Sridhar Chellappa wrote:

> Julian Elischer wrote:
> 
> >
> >On Tue, 3 Feb 2004, Sridhar Chellappa wrote:
> >
> >>Sridhar Chellappa wrote:
> >>
> >>>As part of the Bootup sequence, I see create_pagetables allocate only 
> >>>30 Pages for Page Table entries in non-PAE mode and 120 pages in PAE 
> >>>mode. Does this mean that all the kernel mode entities get only 4 * 30 
> >>>* 1024 * 1024 = 120 MB worth of Address Space ? Can I tune the kernel 
> >>>virtual address space by just changing the "NKPT" define in pmap.h ?
> >>>
> >>>Also, I heard that the BSD kernel(atleast from 5.1 onward) itself is 
> >>>pre-emptible and none of the kernel threads have a cpu affinity. How 
> >>>do I change the behaviour to make the kernel non-preemptible and tie 
> >>>kernel-threads to a particular CPU ?
> >>>
> >>>Sridhar.
> >>>
> >>>_______________________________________________
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> >>>http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
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> >>>"freebsd-hackers-unsubscribe at freebsd.org"
> >>>
> >>Under Linux, all kernel threads share the same "Kernel" Virtual Address 
> >>Space. Is it the same under freeBSD ? If it is not, then what sort of 
> >>Stuff gets put into the "Kernel" Virtual Address Space?
> >>
> >
> >The simple answer is: "yes they do".
> >
> >>
> >>
> >>_______________________________________________
> >>freebsd-hackers at freebsd.org mailing list
> >>http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
> >>To unsubscribe, send any mail to "freebsd-hackers-unsubscribe at freebsd.org"
> >>
> Is it possible for freeBSD kernel threads to have their own private 
> virtual address space ??

Anything is theoretically possible..
each kernel 'thread' is at this time a separate kernel process and can
thus have it's own page tables etc. 

the fact that we don't do that doesn't make it theoretically impossible
:-)



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