SUMMARY: switch between 64 bit and 32 bit.

From: Kumar, Siva (GOS) (
Date: Mon Oct 04 1999 - 10:55:01 CDT

> I upgraded a 2.6 Ultra-2 Box to Solaris 7 and performed
> Flash-PROM update (jumper settings) and so forth to make
> it as 64 bit OS. Strangly enough some apps are running much s
> lower than the past (32 bit).So I would like to revert back
> to 32-bit mode to test this out.
> I attempted to boot this box at OK prompt using
> "boot kernel/unix -as" (as man pages described) and no use.
> Any clues or suggestions?. Will Summarize.

Response from Roger

Should have worked. Try /usr/sbin/isainfo to see what mode the
kernel is booted in. If you don't see 64 bit apps, you aren't
in that mode.

Response from Scott:

Sure... You need to edit the /platform/sun4u/boot.conf file and comment
out the line that says "ALLOW_64BIT_KERNEL_ON_UltraSPARC_1_CPU=true". I
do not know if "false" will work there instead, but it came commented out
and I had to uncomment it in order to boot a 64 bit kernel instead of the
32 bit kernel.

Response from Casper

"boot kernel/unix" should work.
Have you tried "isainfo -kv"?

My note.

Thanks for the responses from Casper, Scott and Roger. Still it does not
Well, I am planning to discuss with SUN and will send the update if it


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