Re: [GIT PULL] Linux KVM tool for v3.7-rc0

From: Markus Trippelsdorf
Date: Sun Oct 21 2012 - 13:54:15 EST


On 2012.10.21 at 19:51 +0200, Ingo Molnar wrote:
>
> * Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx> wrote:
>
> > On 2012.10.21 at 19:15 +0200, Borislav Petkov wrote:
> > > On Sun, Oct 21, 2012 at 05:03:05PM +0200, Ingo Molnar wrote:
> > > > The best way to compare them would be a script that gives exactly the
> > > > same test environment that 'vm run' / 'vm sandbox' does out of box,
> > > > but using qemu.
> > > >
> > > > If such a script is available then that would certainly be a useful
> > > > testing option to kernel developers.
> > >
> > > Right,
> > >
> > > I gotta say, I've mucked around with qemu/kvm net options as a novice
> > > user and haven't always been successfu. If you get host networking
> > > straight away in lkvm then that's another clear point for tools/kvm.
> > >
> > > Same holds true for copying data back and forth between host and guest.
> >
> > I'm agnostic about lkvm, but the following command does all the above:
> >
> > qemu-system-x86_64 -enable-kvm -net nic,vlan=0,model=virtio
> > -net user -fsdev
> > local,security_model=passthrough,id=root,path=/ -device
> > virtio-9p-pci,id=root,fsdev=root,mount_tag=/dev/root -m 512
> > -smp 2 -kernel /usr/src/linux/arch/x86/boot/bzImage -nographic
> > -append "init=/bin/zsh root=/dev/root console=ttyS0
> > kgdboc=ttyS0 rootflags=rw,trans=virtio rootfstype=9p ip=dhcp"
> >
> > If you want your host root-fs to be mounted rw (to copy data
> > back and forth) you need to run to above as root and add "rw"
> > to the kernel options.
>
> Why does it have to run as root? I run 'vm' unprivileged (other
> than /dev/kvm access).

>From the qemu man page:

security_model=security_model

Specifies the security model to be used for this export path. Supported
security models are "passthrough", "mapped- xattr", "mapped-file" and "none".
In "passthrough" security model, files are stored using the same credentials as
they are created on the guest. This requires QEMU to run as root.

--
Markus
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