[SunRescue] Problem with Ultra 1

[Bill Bradford]

On Fri, Apr 14, 2000 at 01:31:25AM -0700, Mike Nicewonger wrote:
> Hi All,
> I've just loaded Solaris 7 on one of the Ultra's I have here, upon booting
> it says, 64 bit OS loaded, 32 bit OS is default for this processor type,
> loading 32 bit OS.....
> What gives? I have the 3.11.1 firmware loaded, now what is going on? How do
> I correct this? What are the winning Lotto numbers? <oops!> :)
> Mike N

There's a bug in some revisions of the UltraSPARC chip that can let a 
normal user hang the system with the right code in 64-bit mode, so these
systems default to 32-bit mode regardless of ROM level.  It should tell
you to see the "boot" manpage:

     On systems containing 200MHz or lower  UltraSPARC-1  proces-
     sors,  it  is  possible  for  a user to run a 64-bit program
     designed to exploit a problem that could cause  a  processor
     to stall. Since 64-bit progams cannot run on the 32-bit ker-
     nel, the 32-bit kernel is chosen as  the  default   file  on
     these  systems.

     The code sequence that exploits the problem is very  unusual
     and  is  not likely to be generated by a compiler. Assembler
     code had to be specifically written to demonstrate the prob-
     lem.  It  is  highly  unlikely that a legitimate handwritten
     assembler routine would use this code sequence.

      Users willing to assume the risk that a user might acciden-
     tally  or  deliberately  run  a program that was designed to
     cause a processor to stall may choose to run the 64-bit ker-
     nel    by    modifying   the   boot    policy   file.   Edit
     /platform/platform-name/boot.conf so  that  it  contains  an
     uncommented     line     with     the     variable     named
     ALLOW_64BIT_KERNEL_ON_UltraSPARC_1_CPU set to the value true
     as shown in the example that follows:

     ALLOW_64BIT_KERNEL_ON_UltraSPARC_1_CPU=true

     For more information, see the Sun Hardware Platform Guide.

-- 
+--------------------+-------------------+
|   Bill Bradford    |   Austin, Texas   |
+--------------------+-------------------+
| mrbill at sunhelp.org | mrbill at mrbill.net |
+--------------------+-------------------+