open /dev/kvm: No such file or directory

open /dev/kvm: No such file or directory

[Jeff Chua]

On linux-26..20-rc2, "modprobe kvm-intel" loaded the module
successful, but running qemu returns a error ...

/usr/local/kvm/bin/qemu -hda vdisk.img -cdrom cd.iso -boot d -m 128
open /dev/kvm: No such file or directory
Could not initialize KVM, will disable KVM support

/dev/kvm does not exist.... should I create this before running qemu?
If so, what's the parameters to "mknod"?


Thanks,
Jeff.

RE: open /dev/kvm: No such file or directory

[Dor Laor]

>On linux-26..20-rc2, "modprobe kvm-intel" loaded the module
>successful, but running qemu returns a error ...
>
>/usr/local/kvm/bin/qemu -hda vdisk.img -cdrom cd.iso -boot d -m 128
>open /dev/kvm: No such file or directory
>Could not initialize KVM, will disable KVM support

Are you sure the kvm_intel & kvm modules are loaded?
Maybe you're bios does not support virtualization.
Please check your dmesg.

>
>/dev/kvm does not exist.... should I create this before running qemu?
>If so, what's the parameters to "mknod"?

It's a dynamic misc device, you don't need to create it.

>
>
>Thanks,
>Jeff.
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Re: open /dev/kvm: No such file or directory

[Jeff Chua]

On 12/28/06, Dor Laor <dor.laor@qumranet.com> wrote:
> Are you sure the kvm_intel & kvm modules are loaded?

Yes.

> Maybe you're bios does not support virtualization.

Configured in the bios on Dell 745.

> Please check your dmesg.

I'll double-check dmesg when I get to the office tomorrow. But I'm
pretty sure it's loaded successfully on the Dell Optiplex 745. On my
IBM X60s notebook, it failed to load.


> It's a dynamic misc device, you don't need to create it.

But it'll be nice to be able to manually create the device as I
normally mount "/" as read-only?


Thanks,
Jeff.

Re: open /dev/kvm: No such file or directory

[Avi Kivity]

Jeff Chua wrote:
>
>> It's a dynamic misc device, you don't need to create it.
>
> But it'll be nice to be able to manually create the device as I
> normally mount "/" as read-only?
>

udev is the best solution here.  It works with read-only root as it 
mounts tmpfs on /dev.

-- 
error compiling committee.c: too many arguments to function

Re: open /dev/kvm: No such file or directory

[Jeff Chua]

On 12/28/06, Avi Kivity <avi@argo.co.il> wrote:

> udev is the best solution here.  It works with read-only root as it
> mounts tmpfs on /dev.

Thanks for the suggestion and I'll look into it. As for now, my system
works well without udev, and I just wanted to test kvm without the
"dynamic" /dev/kvm feature if possible.

Would it be possible to create /dev/kvm once and let it stay there
permanently? How about a switch for non-udev system?

Thanks,
Jeff.

Re: open /dev/kvm: No such file or directory

[Avi Kivity]

Jeff Chua wrote:
> On 12/28/06, Avi Kivity <avi@argo.co.il> wrote:
>
>> udev is the best solution here.  It works with read-only root as it
>> mounts tmpfs on /dev.
>
> Thanks for the suggestion and I'll look into it. As for now, my system
> works well without udev, and I just wanted to test kvm without the
> "dynamic" /dev/kvm feature if possible.
>
> Would it be possible to create /dev/kvm once and let it stay there
> permanently? How about a switch for non-udev system?

[cc'ing udev guru]

Greg, /dev/kvm is a MISC_DYNAMIC_MINOR device.  Is there any way of 
using it without udev?  Should I allocate a static number?


-- 
error compiling committee.c: too many arguments to function

Re: open /dev/kvm: No such file or directory

[Jeff Chua]

On 12/28/06, Jeff Chua <jeff.chua.linux@gmail.com> wrote:
> > Are you sure the kvm_intel & kvm modules are loaded?
> > Please check your dmesg.

I checked and it's loaded ...

Module                  Size     Used by
kvm_intel              18572  0
kvm                      46276  1 kvm_intel

Any chance of getting a static /dev/kvm ?

Thanks,
Jeff.

Re: open /dev/kvm: No such file or directory

[Arnd Bergmann]

On Thursday 28 December 2006 16:51, Avi Kivity wrote:
> Greg, /dev/kvm is a MISC_DYNAMIC_MINOR device.  Is there any way of
> using it without udev?  Should I allocate a static number?

You can write a small script that parses /proc/misc and creates the device,
like

# /sbin/mknod /dev/kvm c 10 `grep '\<kvm\>' /proc/misc | cut -f 1 -d\ `

If you already have an init script, e.g. to set up tun/tap devices,
it would make sense to put it in there.

	Arnd <><

Re: open /dev/kvm: No such file or directory

[Jeff Chua]

On 12/29/06, Arnd Bergmann <arnd@arndb.de> wrote:
> On Thursday 28 December 2006 16:51, Avi Kivity wrote:
> > Greg, /dev/kvm is a MISC_DYNAMIC_MINOR device. Is there any way of
> > using it without udev? Should I allocate a static number?
>
> You can write a small script that parses /proc/misc and creates the device,
> like
>
> # /sbin/mknod /dev/kvm c 10 `grep '\<kvm\>' /proc/misc | cut -f 1 -d\ `
>
> If you already have an init script, e.g. to set up tun/tap devices,
> it would make sense to put it in there.
>
>         Arnd <><
>

That works. That's exacting what I'm looking for.

Thank you,
Jeff.

Re: open /dev/kvm: No such file or directory

[H. Peter Anvin]

Avi Kivity wrote:
> 
> Greg, /dev/kvm is a MISC_DYNAMIC_MINOR device.  Is there any way of 
> using it without udev?  Should I allocate a static number?
> 

Especially for something like /dev/kvm, I think it would make sense to 
allocate a static number for it.

	-hpa