9fans archive / 1998 / 08 / 2 /    prev next

From: Erik Theisen etheisen@min...
Subject: [9fans] PC's 16MB SEGMAPSIZE limitations.
Date: Sat, 01 Aug 1998 18:47:00 -0400

After applying all the AT&T updates to "Plan 9", I tried to rebuild the
world.   Several items refused to compile due to "out of mem"
conditions, namely some of the larger things in libtiff.

After digging around, I see that the maximum segment size is 16MB for
PCs (mem.h - SEGMAPSIZE).   This would explain the behavior I'm seeing
out of the 8c compiler as it uses sbrk to extend its BSS segment up to
16MB before it dies.

I tried bumping SEGMAPSIZE to 64 and the machine became unstable.  Seems
there are other hard coded limits throughout the Plan 9 PC kernel, 16,
64, 128 etc.  It appears that the maximum process footprint is limited
to 64MB.  This is a truly sad condition for modern machines.

Has anyone had luck getting the 9 PC kernel out of the 16MB gear?

Ciao,
Erik