Determining a 32 vs. a 64 bit kernel/CPU

Determining a 32 vs. a 64 bit kernel / CPU

There's a few ways avialable.

Using uname to check the machine hardware name:

32bit:

$ uname -m
i386

$ uname -m
i486

$ uname -m
i586

$ uname -m
i686

64bit:
```
$ uname -m
x86_64

$ uname -m
ia64
```

Checking a system binary (note - use a system binary as in the following because it should represent the system):

32bit:

$ file /sbin/init 
/sbin/init: ELF 32-bit LSB executable, ...

64bit:

$ file /sbin/init 
/sbin/init: ELF 64-bit LSB executable, ...

Checking for the "lm" CPU flag indicates hardware capability (but not necessarily that the running kernel is in 64 bit mode):

32bit:
```
$ grep 'flags.* lm ' /proc/cpuinfo
```

64bit:

$ grep 'flags.* lm ' /proc/cpuinfo
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc rep_good pni monitor cx16 popcnt lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt

References:

BradsWiki: Determining a 32 vs. a 64 bit kernel/CPU (last edited 2011-03-01 11:07:53 by BradleyDean)