Re: [Qemu-devel] [PATCH v4 1/3] i386/cpu: add crash-information QOM property

[Eric Blake]

On 02/14/2017 12:25 AM, Denis V. Lunev wrote:
> From: Anton Nefedov <address@hidden>
> 
> Windows reports BSOD parameters through Hyper-V crash MSRs. This
> information is very useful for initial crash analysis and thus
> it would be nice to have a way to fetch it.
> 
> Signed-off-by: Anton Nefedov <address@hidden>
> Signed-off-by: Denis V. Lunev <address@hidden>
> ---

> +++ b/qapi-schema.json
> @@ -5846,6 +5846,30 @@
>    'data': [ 'pause', 'poweroff' ] }
>  
>  ##
> +# @GuestPanicInformation:
> +#
> +# Information about a guest panic
> +#
> +# Since: 2.9
> +##
> +{'union': 'GuestPanicInformation',
> + 'data': { 'hyper-v': 'GuestPanicInformationHyperV' } }
> +

Markus has been trying to eliminate the addition of new "simple unions"
- while they are syntactically shorter in the .json file, they are
bulkier over the wire with extra {} nesting, and more verbose in the C
code, when compared to using a flat union instead.  I won't necessarily
hold up this patch as-is, but if we are going to avoid new simple
unions, we have to change this before 2.9 bakes in the {} nesting (we
can convert a simple union to a flat union without breaking QMP
back-compat, but it's messier than if we avoid the nesting to begin with).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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