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Date: Tue, 16 Jan 2007 17:28:20 -0600
From: Brian Ford <Brian DOT Ford AT FlightSafety DOT com>
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Subject: Re: 1.7.0 CVS mmap failure
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On Wed, 10 Jan 2007, Brian Ford wrote:

> On Wed, 10 Jan 2007, Corinna Vinschen wrote:
>
> > I implemented the above mentioned technique, which isn't much code
> > anyway.  It reserves a memory lot big enough to fit in the whole
> > mapping, memorizes the address, free's the memory again and then uses
> > the new address in the subsequent real mappings.
> >
> > This should work (knock on wood) on all systems now.  My testcases still
> > work on my 512 MB machine, so I'd appreciate if you could give the latest
> > snapshot a try on /3GB enabled machines.
>
> Yes, this fixes my STC and the application from which it was derived.
> Thanks.

But, it breaks another application that supplies a suggested mmap address
(not MAP_FIXED) that is not available.  The VirtualAlloc needs a retry in
that case.  Maybe the retries can then be removed from the other two
locations?

I'd try a patch, but I'm afraid I'd not catch all the cases
correctly.  Let me know if you'd prefer I try anyway.

Thanks.

PS: In an strace of this, I see three fstat64s called from within a
single mmap64.  Do you know where they all are, and if two should be
optimized away?

-- 
Brian Ford
Lead Realtime Software Engineer
VITAL - Visual Simulation Systems
FlightSafety International
the best safety device in any aircraft is a well-trained crew...



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