Re: [Qemu-devel] [PATCH 1/2] qapi: Do not expose "allow-preconfig" in query-qmp-schema

[Eric Blake]

On 07/05/2018 04:14 AM, Markus Armbruster wrote:
> According to commit 047f7038f58, option --preconfig
>
>      [...] allows pausing QEMU in the new RUN_STATE_PRECONFIG state,
>      allowing the configuration of QEMU from QMP before the machine
>      jumps into board initialization code of machine_run_board_init()
>
>      The intent is to allow management to query machine state and
>      additionally configure it using previous query results within one
>      QEMU instance (i.e. eliminate the need to start QEMU twice, 1st to
>      query board specific parameters and 2nd for actual VM start using
>      query results for additional parameters).

> The command flag is exposed in query-qmp-schema (also commit
> d6fe3d02e9a).  This makes it ABI.
>
> I consider the whole thing an offensively ugly hack, but sometimes an
> ugly hack is the best we can do to solve a problem people have.
>
> The need described by the commit message quote above is genuine.  The
> proper solution would be a main loop that permits complete
> configuration via QMP.  This is out of reach, thus the hack.

> Revert exactly (4), plus a bit of documentation added to
> qemu-tech.info in commit 047f7038f58.
>
> Shrinks query-qmp-schema's output from 126.5KiB to 121.8KiB for me.
>
> Signed-off-by: Markus Armbruster <address@hidden>
> ---
>   qapi/introspect.json       | 5 +----
>   qemu-tech.texi             | 3 ---
>   scripts/qapi/introspect.py | 3 +--
>   3 files changed, 2 insertions(+), 9 deletions(-)

Good reasons for not baking it into the ABI just yet (similar to how we 
did not bake OOB into the 2.12 ABI).

Reviewed-by: Eric Blake <address@hidden>

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org