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bzlaskar 08-11-2009 06:14 AM

determinig whether CPU supports 64 bit processing in a linux box.
 
Greetings all ,

I need to know whether the CPU is enabled for 64-bit processing or
not. I tried reading /proc/cpuinfo , bit it is not telling me clearly
whether the CPU is 64 bit or 32 bit.
I can see some 'ht' flag in the output /proc/cpuinfo but not sure
whether it is telling me whether the CPU is enabled for hyper
threading or it is indicating a 64 bit processor. I installed
dcidecode and it is describing htt flag as "Hyper threading
technology" .
===
$ grep ht /proc/cpuinfo
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx
lm pni monitor ds_cpl est tm2 xtpr
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx
lm pni monitor ds_cpl est tm2 xtpr
-==

Can somebody please clarify whether the 'ht' flag enabled in the
output of /proc/cpuinfo is indicating a 64 bit processor .
Apart from that , what other command we can use that will help to
determine whether the cpu is enabled for 64 bit prcoessing or not.


Thanks in Advance
Zaman

Oakems 08-11-2009 06:27 AM

If you have a spare disk, you could always try to boot a 64bit OS on the PC. It will either load or not.

AlucardZero 08-11-2009 07:51 AM

flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx
lm pni monitor ds_cpl est tm2 xtpr

It supports 64-bit.

Shadow_7 08-11-2009 08:10 AM

Look for "lm" in the flags part of /proc/cpuinfo. It must be "lm" and not "lahf_lm". The later is only partially 64 bit. Not that it helps when manufacturers don't even change the chipset name. Worst case scenario, try it and if it fails... it's not. But it looks like you have lm, so yours is (if only in theory). Otherwise disect cpuid and cross reference sandpile.org and other sites. (most of which is decoded in cpuinfo anyway)


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