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Date: Tue, 12 Mar 2002 21:34:15 -0500
From: Christopher Faylor <cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: mmap of large amount returns invalid pointer
Message-ID: <20020313023415.GB20897@redhat.com>
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On Tue, Mar 12, 2002 at 06:21:15PM -0800, Stephen Weeks wrote:
>
>> looks like you have overlooked that mmap doesn't return NULL
>> despite win32 error in strace (see below):
>> 
>> c:\>net helpmsg 1455
>> 
>> The paging file is too small for this operation to complete.
>
>Thanks for pointing that out.  I agree that it looks like the Cygwin
>dll is failing to check for the Win32 error, which should have caused
>mmap to return -1.
>
>But even if that is fixed, I don't understand why Cygwin/mmap is
>unable to obtain the memory.  My earlier message showed that at the
>start of the program the information returned by GlobalMemoryStatus
>shows that there is easily >300Mb available.
>
>TotalPhys: 209113088
>AvailPhys: 166580224
>TotalPageFile: 309587968
>AvailPageFile: 275365888
>TotalVirtual: 2147352576
>AvailVirtual: 1589841920
>
>I tried a modified version of the program that uses VirtualAlloc/Free
>instead of mmap/munmap and it is able to allocate, zero, and free
>300Mb.

Sounds like you should be looking at the cygwin source code.  That's
the best way to achieve clarity in cases like this.

cgf
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