*BSD News Article 37324


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From: ar@zeus.uk.mdis.com (Alastair Rae)
Subject: Re: mmap() returns errno = 5. Any Clues??
Reply-To: arae@mdis.com
Organization: MDIS (McDonnell Information Systems) UK
Date: Thu, 27 Oct 1994 12:46:10 GMT
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Anthony D Alston (ada@grumpy.mnfep.nn.inri.com) wrote:
> The following line fails when trying to memory map a file thats
> on a NFS mount directory. mmap() returns 0xffffff and errno = 5. 

> This line works fine when the file is on a local file system.

> addr = mmap(0, map_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0l);

> I'm running SunOS 4.1.1

Hum. Do you really expect to be able to do bit-mapped i/o on a shared
remote file? I don't think NFS is that clever.

Purely conjecture but I'd guess you *might* be able to do MAP_PRIVATE
stuff and then sync with memcntl(MC_SYNC).

I'm surprised you got EIO. mmap(2) doesn't mention this in the list of errors.
I'd expect maybe ENODEV or EINVAL.

--
Alastair Rae : arae@mdis.com
The opinions expressed here are probably not those of my employers