Re: [Qemu-devel] Re: [kvm-devel] [PATCH][RFC] Allowing QEMU to directly execute a directory (and storing command line options in it)

[Philip Boulain <prb@ecs.soton.ac.uk>]

On Mon, 2007-09-03 at 12:01 +0200, Christian Brunschen wrote:
> On 3 Sep 2007, at 11:19, Philip Boulain wrote:
> > What's the difference between having to hack about a plain-text,  
> > few-lines configuration file, and a plain-text, few-lines shell  
> > script?
> The same shells are not (at least by default) available on all  
> platforms.

You only need sh, because all you're doing is an exec, which covers all
POSIX platforms. For Windows, use a shortcut.

> Basically, requiring a shell script means that you have to meta- 
> program around qemu itself, whereas a configuration file means you're  
> writing something within the context of qemu (and thus don't have to  
> venture outside qemu's domain).

Given that the goal is "simple", I'd consider this a plus. 95% of
UNIX-like systems is glue.[1]

> 2) if 'foo' is a directory:
>    verify that 'foo' is in fact a vm bundle directory...

If this is going to move from frontends to QEMU itself, given that the Q
devs have already created a QEMU VM bundle format, it makes sense to use
theirs. It's a sensible format, consistent at least with OS X bundle
conventions. (Not sure about GNUStep bundles, but given that their both
NeXT offspring, I doubt there's much difference.)

> Saying that 'Q already handles this' means that any other program  
> that wants to offer a similar ease-of-use would have to be able to  
> read and interpret Q's configuration file format.

I don't see a problem with this.

> If instead there is  
> a wrapper-neutral format, then each wrapper can use that.

This is what Q bundles should be absorbed as. For "simple", there are
shell scripts. For "complete", there are bundles, and Q's format is a
good one to absorb as "the QEMU bundle format". I don't see the point in
a config format which adds nothing but complexity over a shell script.

LionsPhil

1. This figure drawn from entirely unauthoritative sources. ;)