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Date: Sun, 7 Jan 2007 11:58:44 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
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Subject: Re: 1.7.0 CVS mmap failure
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On Jan  6 07:45, Christopher Layne wrote:
> (warning a bunch of strace, scroll wide).
> 
> So I haven't been able to totally nail anything down on this issue due
> to the incredible complexity of Cygwin's mmap interface.

Lots of comments throughout the file...

> This is 2 simple mmap()s in succession, 1st is 46121 bytes, 2nd is 111 bytes.
> Both opened read/write. The second mmap always fails. This is the current
> snapshot code.
> 
> In the 2nd strace, I changed the mmap logic to stop trying to align the 1st
> map on a 4k granularity boundary and just allocate a single map w/ 64k of
> left over dead space (what I would typically expect in posix land). I also
> added more debug info at various stages to try and figure things out. When
> changing it to use 64k period, the mmaps are both successful - which is good,
> but VirtualProtect always fails, no matter what, on unmap.

The strace is rather useless without the (hopefully very short) source
code of the (hopefully very small) testcase.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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