Shared Memory in BSD4.3 is lacking?

[Bill.Stewart.<ho95c>]

In article <2368 at umd5.umd.edu> chris at trantor.umd.edu (Chris Torek) writes:
:>In article <2329 at umd5.umd.edu> I wrote:
:>:System V shared memory is wrong.  (Now there is a good flammable

:In article <2009 at ho95e.ATT.COM> wcs at ho95e.UUCP
:>Ok, I'll flame!  What's wrong with System V shared memory?

[various good responses from Chris, Mike Ditto, and others]

Yeah, I agree IPC really should be attached to the file system,
though I'm not sure whether it should look like a regular file or
like some variant on the "pipe" special file type or a character-special.
Some of the "reasonable" implementations start to look appallingly like mmap().


:>I agree that the user interface is annoying,
:(It feels like something IBM might have invented.)
Ouch, that's getting nasty :-)!

:Additionally, the total number of shared pages allowed is, I believe,
:compiled into the kernel.
It's at least configurable.  On some architectures, with ancient or bizarre
MMUs, it's tough to be flexible.

:Finally, there is, it seems, no way to have sbrk and shm*
:co-operate.
This doesn't bother me much - sbrk is inherently dealing with a different
memory space.  But it *would* be nice to have malloc() able to use shm.

:The future BSD shared memory will cure all of these
:defects, or at least we think so....
If you do it right, it may be possible to write a System-V IPC emulation
library, to preserve existing software.

			Bill Stewart, ho95c!wcs

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#				Thanks;
# Bill Stewart, AT&T Bell Labs 2G218, Holmdel NJ 1-201-949-0705 ihnp4!ho95c!wcs