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Date: | Fri, 5 Jan 2007 08:17:51 -0800 |
From: | Christopher Layne <clayne AT anodized DOT com> |
To: | cygwin AT cygwin DOT com |
Subject: | Re: 1.7.0 CVS mmap failure |
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mmap() is supposed to zero-fill, not refuse to map when len is less than the system page size. I have never ever seen mmap() fail to map less than page size on any typical Posix system. " The system shall always zero-fill any partial page at the end of an object. Further, the system shall never write out any modified portions of the last page of an object which are beyond its end. References within the address range starting at pa and continuing for len bytes to whole pages following the end of an object shall result in delivery of a SIGBUS signal. " Back to the original issue, consider this: MEM_TOP_DOWN 0x100000 Allocates memory at the highest possible address. If there were any kind of simple arithmetic bug behind mmap()'s scenes (such as computing space to zero-fill, etc. etc.) I would think ENOMEM would be a very common scenario if we're allocating near the end of addressible space. -cl On Fri, Jan 05, 2007 at 05:06:50PM +0100, Samuel Thibault wrote: > Not sure about the cygwin state, but at least on the Linux/Posix side, > mmap() is not supposed to be able to work with a smaller granularity > than a memory page. > > Samuel -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
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