Re: [PATCH 10/12] target-info: add -target and program-name selection

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Aug 26, 2026 at 01:46:17PM +0100, Daniel P. Berrangé wrote:
> On Sun, Aug 23, 2026 at 11:07:28PM +0800, Yonggang Luo wrote:
> > - Parse -target before TargetInfo is fixed; CLI overrides the program
> >   basename.
> > - Tokens are target_name or target_name-be / -le; -target help lists
> >   registered names in sorted order.
> > - When -target is omitted, infer the token from g_get_prgname(): strip
> >   .exe, take the longest dash-separated registered suffix, and retry
> >   without a trailing w for Windows GUI binaries.
> > - A basename that matches no registered token falls through to the
> >   unique default. Combined binaries with no suffix require -target
> >   when more than one default TargetInfo is registered.
> 
> IMHO this -target argument and the target interference from
> program name is a mistaken direction.  We're being led off
> course by the attempt to make the new qemu-system be identical
> to qemu-system-$TARGET.
> 
> If we ignore historical compat and treat qemu-system as a
> clean break, then I'd suggest that 'target' is not a concept
> to be exposed to the user at all.
> 
> The user cares about the machine (and CPUs) they want to run,
> and their choice in this respect is what should determine the
> target(s) QEMU needs to enable. We should take
> 
>   qemu-system --machine vexpress-a15
> 
> that tells us we need the arm target. If we need to distinguish
> arm7 vs aarch64, then the choice of -cpu should determine 32
> bs 64 bit.
> 
> This extends better into the future world where we have
> machine type that could involve CPUs from multiple targets.
> 
> IOW machine config option / QOM class is what we should pivot
> off rather than a global target config option.

I forgot to mention that this is also pretty important for making
introspection work, as we need to be able to say

  'qemu-system --machine none -qmp ...'

and connect to QMP to introspect the binary. Having to add a
'--target <name>' into that mix is undesirable, as it creates
a chicken & egg problem. You don't know what targets are built
into qemu-system without introspecting it and you can't
introspect it without selecting a target to introspect.


With regards,
Daniel
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