Transmeta Crusoe undocumented




Transmeta Crusoe undocumented featuresLast Update: 2000-09-29


IntroductionSince its release in early 2000, Transmeta Crusoe remains
the most mysterious x86 CPU. It's the only contemporary CPU for which the common
documents are not available to an average human being. I registered to receive
the Crusoe documents as soon as they opened their website, and I still didn't
get ANY answer from them. So I started searching for information on Crusoe that
could be more precise than the general desciption available everywhere. Here
are some results of my hunting:


CPUID on Transmeta CrusoeTransmeta crusoe supports standard CPUID,
AMD-style extended CPUID and its very own extended CPUID (somehow I believe that
the last one can be attributed to Christian). Of these, the Transmeta extended
CPUID is of course the most interesting one. Here it is:
EAX=0x80860000Return the maximim Transmeta CPUID level in EAX.
EAX=0x80860001CPU detailed revision, (nominal?) operating frequency and
Transmeta features(operating mode?). EBX = CPU revision ECX = nominal
frequency EDX = features:

bit 0 - LongRun power management supported
bit 1 - ???
EAX=0x80860002Code Morphing Software revision EBX:ECX - software
revision
EAX=0x80860003..0x80860006CPU name string. The CPU name string is
64 bytes long. It starts with LSB of EAX returned by CPUID 0x80860003 and ends
with the MSB of EDX returned by CPUID 0x80860006.
EAX=0x80860007Current CPU operation information. EAX = core
frequency EBX = core voltage ECX = performance percentage


Crusoe MSRs
MSR 0x80860010(based on Transmeta presentation at Hot Chips 12,
extracted by Christian Ludloff) bits 63..32 = max. performance percentage
bits 31..0 = min. performance percentage


Copyright 2000 by G. Mazur