Re: [PATCH 5/7] kvm tools: Add help and info messages to 'kvm setup'

[Ingo Molnar <mingo@elte.hu>]

* Asias He <asias.hejun@gmail.com> wrote:

> On 10/14/2011 02:22 AM, Pekka Enberg wrote:
> > On Thu, Oct 13, 2011 at 7:52 PM, Ingo Molnar <mingo@elte.hu> wrote:
> >>>> Btw., will 'kvm run' select the last-created rootfs by default?
> >>>
> >>> No, it runs rootfs that's named 'default'. We can change that but
> >>> I'm not completely convinced running that last-created rootfs is
> >>> the right thing to do here. Hmm.
> >>
> >> I'm not convinced either - just wanted to raise the issue.
> > 
> > Right. So 'kvm run' is supposed to setup and launch a 'default' rootfs
> > if no rootfs is specified.
> > 
> >> Also, i raised this in the other thread, why not use .kvmtool of the
> >> current directory? That way it's cwd local like Git and perf. A 'kvm
> >> run' (union?) mount the cwd or so - so this would be a natural
> >> equivalent to chroot. The $HOME/.kvmtool is a Qemu-ish global
> >> workflow.
> > 
> > Yeah, that definitely makes sense. 'kvm setup rootfs' wouldn't create
> > rootfs under $HOME/.kvmtool/rootfs but under $(PWD)/rootfs.
> 
> I also think $(PWD)/rootfs is much better than 
> $HOME/.kvmtool/rootfs. I think 'kvm setup $absolute_rootfs_path' 
> make sense as well.

The nice thing about $CWD and chroot is that it takes the current 
directly as the 'root directory' of the chroot environment.

The canonical extension of that would be to create .kvmtool/ in $CWD 
and to union-mount the files in the current directory on top of the 
.kvmtool 'binary environment' - or such.

Or, an approximation of that would be to simply mount $CWD as /home 
of the guest environment.

Thus $CWD/.kvmtool/default/ would be the default root fs (multiple 
instances can be created), and $CWD would be the default /home or 
/host filesystem.

> > I guess we'll lose the ability to 'kvm list' all available rootfs 
> > directories, though?
> 
> User can create and put the rootfs directories where he/she likes. 
> We do not need to track where the rootfs directories is, thus we do 
> not need to 'kvm list' them.

listing the current ones in $CWD would still be handy.

*If* users prefer some kind of global workflow then $HOME/.kvmtool 
can still be special and we can do a 'kvm list --all' kind of thing 
which would also list $HOME/.kvmtool instances.

Or 'kvm list' could list both $CWD and $HOME instances and would be 
able to run them. Naming clashes could be handled via some 
straightforward way, for example by naming the default rootfs in 
$HOME 'global' - it would be in $HOME/.kvmtool/global. The default 
one in $CWD would be named 'local' and be in $CWD/.kvmtool/local.

Or so.

Thanks,

	Ingo