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Date: Tue, 6 Nov 2001 11:46:42 +0100
From: Corinna Vinschen <cygwin AT cygwin DOT com>
To: cygwin <cygwin AT cygwin DOT com>
Subject: Re: 1.1.3: mmap() returns unusable memory segments: segm fault
Message-ID: <20011106114642.D2965@cygbert.vinschen.de>
Mail-Followup-To: cygwin <cygwin AT cygwin DOT com>
References: <20011105220134 DOT I17306 AT cygbert DOT vinschen DOT de> <Pine DOT WNT DOT 4 DOT 33 DOT 0111061112020 DOT 178-100000 AT erde DOT concept DOT de>
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In-Reply-To: <Pine.WNT.4.33.0111061112020.178-100000@erde.concept.de>; from lothar@concept.de on Tue, Nov 06, 2001 at 11:16:07AM +0100

On Tue, Nov 06, 2001 at 11:16:07AM +0100, Lothar Linhard wrote:
> 
> Wow! What a quick respond.  Thank you.
> I'll checkout the CVS tree (anoncvs AT anoncvs DOT cygnus DOT com)
> and see if I can compile cygwin.dll and run more mmap
> tests.

Chris has put the patch into 1.3.4-2 which should be on most mirrors
in the meantime.

However, there are already 5 mmap test applications in the testsuite
so you can see what is already tested.  I will probably add your test
as the sixth.

> Is there a list of limitations of Cygwin's mmap?

No.  There are limitations given due to OS restrictions.  E.g. the
addresses for mmaps which are always < 0x80000000 on NT/2K/XP and
always >= 0x80000000 and < 0xc0000000 on 9x/ME which makes the usage
of MAP_FIXED somewhat complicated.  Or the missing VirtualProtect()
on 9x/ME which doesn't allow to force an invalidation of pages after
munmap().  I would suggest to look on http://msdn.microsoft.com into
the description of MapViewOfFileEx() and CreateFileMapping().  Our
mmap() impementation tries to tweak the Win32 calls so that mmap()
behaves as POSIX conformant as possible but it's not easy to find
all border conditions.

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin AT cygwin DOT com
Red Hat, Inc.

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