From: Rick Moen <rick@linuxmafia.com>
Date: Fri, 6 Apr 2007 18:48:42 -0700
To: conspire@linuxmafia.com
Subject: Re: [conspire] & now I've gone nuts + 64x2

Quoting Bruce Coston (jane_ikari@yahoo.com):

> Bought the 64x2 3800+ AMD CPU w/motherboard combo at Fry's for $90 and the
> x-y = $99 for 2GB of 667 MHz DDR2 SDRAM.

Coolio. Here's something that you're well advised to try on new-ish CPUs, preferably before buying:

Boot a Linux live CD, then check the CPU flags line in /proc/cpuinfo. We're checking for two things: (1) x86_64 support. (2) virtualisation support.

The virtualisation information won't be accurate unless your kernel revision is at least 2.6.15 for Intel CPUs, or 2.6.16 for AMD ones.

Full hardware support for (Xen, KVM) virtualisation requires that the CPU support the "VT" instruction extensions on Intel, or the equivalent "SVM" (aka "AMD-V") extensions on AMD.

Do "grep flags /proc/cpuinfo".

Or, to be fancy about it:
grep vmx /proc/cpuinfo > /dev/null && echo 'Intel VT flag' || echo 'No Intel VT flag'
grep svm /proc/cpuinfo > /dev/null && echo 'AMD-V flag' || echo 'No AMD-V flag'

In 2007, I would not buy an x86 CPU failing either of those two criteria. That is, I'd made sure /proc/cpuinfo showed both "lm" and also either "vmx" or "svm".

NOTE: BIOS Setup configuration must be correct for these CPU instruction extensions to be enabled. You should always check BIOS config on new/unfamiliar systems for that among other reasons.

NOTE2: The virtualisation CPU extensions are necessary to use the full AKA hardware-assisted virtualisation mode, which has the advantage of being able to support arbitrary guest operating systems without the need for a virtualisation-aware guest OS and drivers, but has a significant performance penalty because the hypervisor must invoke the CPU extensions to emulate inside the VMs PC hardware, including a BIOS, disk controller, graphic adapter, USB controller, network adapter, etc. (Hence, MS-Windows can run under full virtualisation.) The alternative of 'paravirtualisation' is an efficient, lightweight virtualisation mode yielding maximum performance, but requires that guest OSes / drivers be paravirtualisation-aware.

> Will the funny interface material on the included heat sink / fan
> really work out OK now that I mounted it, it was easy?

Sorry, can't parse that. Be careful about any thermal-coupling goo or sheets between the CPU and heat sink: You want a very thin layer with maximal surface contact to both pieces. Screw that up, and the CPU can literally char itself.





From: Rick Moen <rick@linuxmafia.com>
Date: Sun, 8 Apr 2007 22:03:01 -0700
To: conspire@linuxmafia.com
Subject: Re: [conspire] & now I've gone nuts + 64x2

Quoting Edmund J. Biow (biow@sbcglobal.net):

> That might be hard to do at Fry's, since the CPUs are all behind a cage
> at the front counter.

Indeed, it does require finding at least one bootable system with one such CPU. However, I'd certainly never buy a CPU at Fry's, anyway. Or RAM or a hard drive, either.

> All X2 CPUs have X86_64 support and AMD-V hardware virtualization
>: support has been including since the "F" steppings of May, 2006.

I've been seeing quite a lot of current Intel CPUs with no vmx flag, FWIW. (I do a fair amount of hardware testing.) No idea whether they're advertised as "X2" or not; I tend to get handed complete systems for testing, and there's no fluffy literature, just stuff you don't want to drop on your foot. (See .signature block.)

-- 
Cheers,                                      Hardware:  The part you kick.
Rick Moen                                    Software:  The part you boot.
rick@linuxmafia.com