[sf-lug] more tutorial videos

Rick Moen rick at linuxmafia.com
Tue Apr 22 12:20:38 PDT 2008

Quoting Alex Kleider (a_kleider at yahoo.com):

> It has to do with some of what he and I were discussing earlier in the
> meeting last evening. Specifically 
> cat /proc/meminfo
> and 
> cat /proc/cpuinfo

Two of the entries in /proc/cpuinfo's "flags" line may be of particular

1.  "lm":  If present, indicates that the CPU supports x86_64 "long mode" 
operations, i.e., is capable of running x86_64 (64-bit P4/Opteron)
operating systems and apps.

2.  "vmx" (Intel) or "svm" (AMD):  Indicates that the CPU includes
instructions[1] making it capable of full virtualisation as opposed to only
paravirtualistion, which in turn means it can do virtualised
environments (VMware, Xen, KVM, etc.) with almost no CPU performance
overhead and _no modifications_ to guest OSes.  These CPU flags show up
only if you're running kernel 2.6.15 or later for Intel, and 2.6.16 or
later for AMD.

So, basically, it's good to verify that any new x86 machine you buy has
both these features in its CPU(s).

A number of years ago, when my wife was an engineer at TiVo, Inc., she
was seeing people on IRC post processor details from their various
machines' /proc/cpuinfo reports.  So, just to fool with their heads, she
posted /proc/cpuinfo from the TiVo Series I she was working on.  (TiVo
DVRs all run Linux.)

  $ cat /proc/cpuinfo
  processor : 0
  cpu : IBM 403GCX
  clock : 54MHz
  revision : 20.1
  bogomips : 53.86
  machine : Teleworld Customer Device 

They were duly mystified.  ("Teleworld" was the original name for the
firm later called "TiVo, Inc."  The Series I used a variety of PowerPC
chip.[2]  Series II and later switched to MIPS CPUs.)

[1] Specifically this means the CPU supports VT-x (aka Vanderpool)
processor instructions on Intel, or AMD-V (aka SVM) instructions on AMD

[2] If that seems startlingly underpowered, realise that a lot of the
heavy lifting is/was done by a separate hardware MPEG encoder/decoder
chip.  Using a CPU roughly comparable to a Pentium 90 minus FPU is part 
of what makes TiVo Series I machines run cool and quiet.

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