Re: unmap() sometimes unmaps more pages than specified

On Thursday 22 June 2006 12:48, Espen Skoglund wrote:
> [Frank Mehnert]
>
> > Hi,
> > in a complex scenario I observed that the unmap() syscall sometimes
> > flushes more pages than specified. So far I could not find a small
> > testcase and therefore have to provide tracelogs of my current
> > scenario:
>
> [...]
>
> > Please tell me if you need more information.
>
> What happened in this scenario was that you had a 4MB mapping that had
> two 4KB mappings mapped into the destination space.  You tried to
> unmap a 4KB mapping in the source space, but there was only a 4MB
> mapping there.  The whole 4MB mapping was as such unmapped instead.
>
> The policy used to be different for early implementations; i.e.,
> instead of unmapping the 4MB page the whole unmap operation was
> ignored.  Completely ignoring the operation is not a good idea,
> though.

Ok, that means that, from the point of the destinations' space view,
L4_Unmap(f=0) called from the destination space is different from
L4_Unmap(f=1) called from the source space, right? This is _very_
difficult to handle for me. I guess you want/can not change the
implementation to consider the outgoing map relations.

Frank
-- 
## InnoTek Systemberatung GmbH, http://www.innotek.de ##

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.3 (GNU/Linux)

iD8DBQBEmoCt6z8pigLf3EcRAjQ9AJ9zf8hm2AvKlEO3R93FeZFNr6NIDQCeMEwk
43ogW8TzrFlOATIKmuM0t3M=
=VNMN
-----END PGP SIGNATURE-----