COMMAND

    kernel

SYSTEMS AFFECTED

    64bit Sol7 on Ultra1 < 200mhz

PROBLEM

    Jake Luck posted following.  Info is based on Solaris7 sparc  boot
    (1m) man pages:

        64-bit SPARC
        Booting UltraSPARC Systems
           Certain platforms may need a firmware  upgrade  to  run  the
           64-bit  kernel.   See  the  Sun  Hardware Platform Guide for
           details. If the 64-bit kernel  packages  are  installed  and
           boot  detects that the platform needs a  firmware upgrade to
           run 64-bit, boot  displays a  message  on  the  console  and
           chooses the 32-bit kernel as the default file instead.

           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
           kernel, 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.

SOLUTION

    Users willing to  assume the risk  that a user  might accidentally
    or  deliberately  run  a  program  that  was  designed  to cause a
    processor  to  stall  may  choose  to  run  the  64-bit  kernel 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