# [SOLVED] KVM support?

## pgu

I'm installing qemu on a Core2 Duo 8400 (stepping 6). According to  http://wiki.gentoo.org/wiki/QEMU a vmx in the processor features means that it supports KVM. But there is no KVM in the Virtualization sub-menu like on my i3 laptop?

There is no /dev/kvm either. Does this mean that hte 8400 does not support KVM despite the vmx flag?Last edited by pgu on Thu Nov 27, 2014 11:19 pm; edited 1 time in total

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## pgu

http://ark.intel.com/products/38512/Intel-Core2-Quad-Processor-Q8400-4M-Cache-2_66-GHz-1333-MHz-FSB says that it supports VT. I can't find anything in the BIOS about VT either, so I don't seem to be able to turn it on if it was off.

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## pgu

Maybe I'll have to upgrade the  BIOS to get a switch to enable VT.

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## NeddySeagoon

pgu,

/dev/kvm comes from enabling KVM support in the kernel.

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## pgu

The problem is that there is no way to select it. The Virtualization menu looks like this:

http://oi60.tinypic.com/t6pm42.jpg

As on my i3 laptop it looks like this:

http://oi58.tinypic.com/2cmrkah.jpg

And when I double checked VT was enabled in the kernel:

http://oi57.tinypic.com/f3ukpv.jpg

What I get in my .config file is:

```

$ gzip -dc /proc/config.gz |grep KVM

CONFIG_HAVE_KVM=y

$ uname -mrp

3.16.5-gentoo x86_64 Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz

```

As on the i3 (by selecting Intel) I get:

```
 

$ gzip -dc /proc/config.gz |grep KVM

CONFIG_HAVE_KVM=y

CONFIG_HAVE_KVM_IRQCHIP=y

CONFIG_HAVE_KVM_IRQ_ROUTING=y

CONFIG_HAVE_KVM_EVENTFD=y

CONFIG_KVM_APIC_ARCHITECTURE=y

CONFIG_KVM_MMIO=y

CONFIG_KVM_ASYNC_PF=y

CONFIG_HAVE_KVM_MSI=y

CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT=y

CONFIG_KVM_VFIO=y

CONFIG_KVM=y

CONFIG_KVM_INTEL=y

# CONFIG_KVM_AMD is not set

# CONFIG_KVM_MMU_AUDIT is not set

CONFIG_KVM_DEVICE_ASSIGNMENT=y

$ uname -mrp

3.16.5-gentoo x86_64 Intel(R) Core(TM) i3-3217U CPU @ 1.80GHz

```

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## Ant P.

You need to enable [General Setup] -> [Timers subsystem] -> [High resolution timers support] to make the KVM option visible.

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## NeddySeagoon

pgu,

To see all the options in menuconfig, even ones you cannot select, press 'z'. Its a toggle, so you can turn the hidden things off again too.

You can than see the option you need and read the "Depends On" in the help.

You may need to do this recursively too, as a  "Depends On" you need might be hidden by another  "Depends On".

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## The Doctor

make xconfig is generally a good choice of you have qt and X installed since it will tell you what you need to enable for a given option to be available.

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## steveL

make nconfig  is a happy medium, that works in console/xterm with enough of a UI to make it less stressful.

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## NeddySeagoon

steveL

Thats nice - it even advertises its show all, unlike menuconfig

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## pgu

Thanks! I've seen the dependencies in the past, but I never noticed that their values were listed as well. HIGH_RES_TIMERS was not set which caused KVM to be false. Now I get:

```
# ls /dev/kvm 

/dev/kvm

```

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## steveL

 *NeddySeagoon wrote:*   

> Thats nice - it even advertises its show all, unlike menuconfig

 

Yeah, one of Griz's tips. ;-)

Only time I see the menuconfig is when I run make oldconfig to see what's changed, before nconfig.

The others will also run the oldconfig check first, automatically, if you've dropped in the .config, but I prefer the conceptual distinction in a workflow. It means I've been forced to see everything new, in a separate stage, when I'm ready to absorb it (sorta;)

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