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Date: Fri, 11 Sep 2009 09:47:53 +0200
From: Gerd Hoffmann <kraxel@redhat.com>
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To: qemu-devel@nongnu.org

On 09/10/09 17:18, Mark McLoughlin wrote:
> Several qemu command line options have a parameter whose value affects
> what other parameters are accepted for the option.
>
> In these cases, we can have an empty description table in the
> QemuOptsList and once the option has been parsed we can use a suitable
> description table to validate the other parameters based on the value of
> that parameter.

Hmm.  The "empty description" mode is intended to be used in case the 
verification isn't done by QemuOpts at all (i.e. for -devices, where the 
qdev property code will do the checks).  I really like to have the 
option description hooked into QemuOptsList.

I can think of two possible ways to do that:

(1) We can stick all possible values info QemuOptsList->desc.  Then
     have separate data structures to describe which fields are allowed
     in which cases (and, while being at it, which fields are mandatory).

(2) We have multiple QemuOptDesc lists for the different cases.

I tend to prefer the first.  We can do the option parsing 
unconditionally in qemu_opt_set() then and don't have two different 
possible code paths for that.

Comments?  Other ideas?

cheers,
   Gerd