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. Because 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.
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.