Difference between “machine hardware”, “processor type” and “hardware platform”

Question

My Linux machine reports "uname -a" outputs as below:

[root@tom i386]# uname -a
Linux tom 2.6.9-89.ELsmp #1 SMP Mon Apr 20 10:34:33 EDT 2009 i686 i686 i386 GNU/Linux
[root@tom i386]#

As per man page of uname, the entries "i686 i686 i386" denotes:

• machine hardware name (i686)
• processor type (i686)
• hardware platform (i386)

Additional information:

[root@tom i386]# cat /proc/cpuinfo

<snip>
vendor_id    : GenuineIntel
CPU family   : 6
model        : 15
model name   : Intel(R) Xeon(R) CPU            5148  @ 2.33 GHz
stepping     : 6
CPU MHz      : 2328.038
cache size   : 4096 KB
</snip>

How to differentiate between these three entries ("i686 i686 i386") ?

Answer 1

The processor type (or name) refers for what architecture has been made the processor.

The hardware machine name must be compatible with the processor type, in other words, must be the same type as the processor type.

And finally, the hardware platform refers to the whole instructions that the hardware uses to process and which it musn't be a higher version than the processor type.

You can't run a i686 set of instructions in a i386 processor for example.

i686 is refered to the 64 bits processors and architectures but referred to the platform, it means both x686 or x86_64, referred to the instructions channel (64 bits).

i386 = 32 bits

Answer 2

using following option you can differentiate between these three entries ("i686 i686 i386") .

[root@tom i386]# uname -a
Linux tom 2.6.9-89.ELsmp #1 SMP Mon Apr 20 10:34:33 EDT 2009 i686 i686 i386 
GNU/Linux
[root@tom i386]#uname -m;                -->machine hardware name
i686
[root@tom i386]#uname -p;                -->processor type
i686
and last one is  hardware platform(i386).