Re: [HACKERS] mmap and MAP_ANON

Bruce Momjian <maillist@candle.pha.pa.us>

From: Bruce Momjian <maillist@candle.pha.pa.us>
To: ocie@paracel.com
Cc: hackers@postgreSQL.org
Date: 1998-05-12T21:17:12Z
Lists: pgsql-hackers
> 
> Bruce Momjian wrote:
> > 
> > > 
> > > Bruce Momjian wrote:
> > > > 
> > > > Would people tell me what platforms do NOT support the MAP_ANON flag to
> > > > the mmap() system call?  You should find it in the mmap() manual page.
> > > 
> > > Doesn't seem to appear in Linux (2.0.30 kernel).  As another poster
> > > commented, /dev/zero can be mapped for anonymous memory.
> > > 
> > 
> > OK, who doesn't have /dev/zero?
> 
> I have been playing around with mmap on Linux.  I have been unable to
> mmap /dev/zero or to use MAP_ANON in conjunction with MAP_SHARED.
> There is no problem sharing memory when a real file is used.
> Solaris-sparc seems to have no trouble sharing memory mapped from
> /dev/zero.  Very strange.

And very bad.  We have to have a 100% usable solution, or have some if
ANON code, else shared memory.

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