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Old 08-30-2005, 02:46 PM   #1
Henry_1
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Registered: Sep 2003
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/proc/cpuinfo flag lm


Hi,

cat /proc/cpuinfo gives

rocessor : 1
vendor_id : GenuineIntel
cpu family : 15
model : 4
model name : Intel(R) Xeon(TM) CPU 3.20GHz
stepping : 1
cpu MHz : 3200.229
cache size : 1024 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 5
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss tm lm
bogomips : 6396.31

I'm assuming the lm flag tells that the cpu has 64 bit extension. Is my assumption correct? I couldn't find much info about it.

Thanks.
 
Old 08-30-2005, 03:01 PM   #2
Matir
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The lm flag is indeed x86-64.

The definitions of the flags can be found in the kernel source tree, in the include/asm/cpufeature.h header.
 
Old 03-15-2007, 09:58 PM   #3
thesmokeyt
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standard flag for x86_64 procs?

so i'm in a similar boat. i'm trying to find out if lm is standard flag for x86_64 procs. couple things i've read make me think so, but i need to be as sure about it as i can.

have you two, or anyone else, ever run into 64 bit procs that do NOT have the lm flag?

if i find out more i'll post it.
thanks.
 
Old 03-15-2007, 10:42 PM   #4
Matir
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The lm flag indicates that the CPU is a 64-bit proc. Thus, all x86-64 cpus have it, and no 32 bit CPUs have it. From /usr/include/asm/cpufeature.h: #define X86_FEATURE_LM (1*32+29) /* Long Mode (x86-64) */
 
Old 11-15-2007, 07:40 AM   #5
mkbane
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Actually I'm pretty sure my Xeon is only 32-bit but yet it shows the 'lm' flags so I need convincing that 'lm' means 64-bit...

michael@ratty:~$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 4
model name : Intel(R) Xeon(TM) CPU 3.00GHz
stepping : 1
cpu MHz : 2793.136
cache size : 1024 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 5
wp : yes
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 lm constant_tsc pni monitor ds_cpl cid cx16 xtpr
bogomips : 5590.38

processor : 1
vendor_id : GenuineIntel
cpu family : 15
model : 4
model name : Intel(R) Xeon(TM) CPU 3.00GHz
stepping : 1
cpu MHz : 2793.136
cache size : 1024 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 5
wp : yes
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 lm constant_tsc pni monitor ds_cpl cid cx16 xtpr
bogomips : 5586.51


I will need to get the exact specs, but it's an Intel Xeon 3.0GHz with hyperthreading bought in Autumn 2004
 
Old 11-15-2007, 11:43 AM   #6
HappyTux
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Quote:
Originally Posted by mkbane View Post
Actually I'm pretty sure my Xeon is only 32-bit but yet it shows the 'lm' flags so I need convincing that 'lm' means 64-bit...
Well get a 64bit live CD/DVD and boot with it then ...
 
Old 11-15-2007, 01:43 PM   #7
mkbane
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aha, I apologise and I learn!

Using info from `dmesg` (Linux) I can determine my Xeon to be a 'SL7PE' and a quick search reveals it does support EM64T. So yes, it supports 64 bit computing. (But is it really a 64bit chip? I'm sure a colleague bought a Xeon after me and it was sold something like "64bit Xeon"...)
 
Old 11-16-2007, 12:37 AM   #8
thesmokeyt
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Sorry, i did not reply sooner. work keeps me really busy.

I'm glad you discovered that lm is 'really' the flag for 64bit capability.

It sounds like to me, that you may have only a 32bit capable motherboard.
It might be worth looking into, and if it is, it might be worth looking into upgrading to a newer one.

cheers,
~smokey
 
  


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