Re: Large Shared Memory

Peter Monta (pmonta@halibut.imedia.com)
Wed, 30 Jun 1999 10:34:26 -0700

> More specifically, I need a contiguous region of memory that can be
> mapped into multiple processes (serially, not simultaneously) on a
> uniprocessor system and persist beyond any particular process.

One way is to reserve some memory outside of Linux with the
"mem=" boot parameter, then mmap() this region of /dev/mem
from user space. (I haven't tried this with 2.2, actually.)
A description can be found under the "Using Shared Memory..."
link at

http://www.rtlinux.org/~rtlinux

This technique is probably simplest if you don't need an
allocator in the kernel for use by drivers. If you do need
this, the other possibility is to use the bigphysarea patch; a
2.2 version can be found on Tom Leete's web page at

http://web.mountain.net/~tleete/

I've found bigphysarea to be really useful.

Cheers,
Peter Monta pmonta@imedia.com
Imedia Corp.

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