# [SOLVED] Xen - Missing cpu flags (including vmx - grrr)

## actionbuddha

Hello,

On a new(ish) Core 2 Duo machine, with Gentoo Sources 2.6.24, I get the following flags when showing cat /proc/cpuinfo:

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 syscall nx

lm constant_tsc arch_perfmon pebs bts rep_good pni monitor ds_cpl vmx est

on the same machine with xen-sources 2.26.21, I get the following:

fpu de tsc msr pae cx8 apic sep mtrr cmov pat clflush

acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc pni ssse3 cx16

Note missing vmx flag, which is needed for Xen to run unmodified guest operating systems. Any ideas why the flag might be missing? Trying to start a guest using the hvm kernel gives:

Error: HVM guest support is unavailable: is VT/AMD-V supported by your CPU and enabled in your BIOS?

Are there specific config options I could check for and may have missed? Any and all help appreciated, this is driving me mad :)

PaulLast edited by actionbuddha on Fri May 23, 2008 9:37 pm; edited 1 time in total

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## actionbuddha

Well, don't I feel like an idiot. VT was disabled in the BIOS, under an obscure 'OS Security' menu option. I was thrown off the scent because of the difference in cpu flags shown under stock linux vs. linux running as dom0 under Xen. Apparently Xen isolates some of the machine capabilities from even dom0. For anybody having similar troubles - xm dmesg | grep -i vmx will show you definitely whether VMX has been picked up or not. You're looking for:

(XEN) HVM: VMX enabled

Best Wishes,

Paul

p.s. excuse my ignorance, but how can I mark this as [SOLVED]?[/topic]

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## bunder

 *actionbuddha wrote:*   

> p.s. excuse my ignorance, but how can I mark this as [SOLVED]?

 

hit the edit button on your first posting and update the subject, hit submit... mind you this is totally optional.

cheers

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