4.0G : can't mmap(2) more than 1 Gb !!

From: Claude Scarpelli <claude_at_genoscope.cns.fr>
Date: Thu, 29 Jun 2000 22:03:59 +0200

Hi Tru64 managers,

I just read the 4.0G releases notes, and found a limitation on the
size of an mmap(2)ed file that didn't exist in previous releases of
the OS :

4.0G Releases Notes says, in chapter A.5 (File System limits) :

      Memory Mapped File Limit

      The supported maximum size of a file that can be mapped into
      memory without segmenting the file is 1 GB.


Which is *very* different from what I read in previous releases (from
4.0B up to 4.0F). From chapter A.1.7 (4.0F) :

      Memory mapped file limit

      The maximum supported size of a file that can be mapped into
      memory without segmenting the file depends on the virtual
      address space limits, as documented in the section on memory
      limits.


ie, the vm-maxvas parameter (which can exceed 1Gb).



The vm-maxvas parameters has the value 12 Gb on our systems (4 GS60 (4
EV6 CPU, 4Gb memory)).

Does it mean that in 4.0G, mmap(2) system calls will fail if the len
parameter exceed 1 Gb ?




-- 
------------------------------------------------------------------------------
Claude Scarpelli                            | Defenestrate: to exit a window
Centre National de Séquençage - GENOSCOPE   | onscreen. (Time International
2, rue Gaston Crémieux, F-91000 EVRY FRANCE | Vol 146, No. 20, Nov 13, 1995)
Received on Thu Jun 29 2000 - 20:05:15 NZST

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