On 10/8/2026 2:46 AM, Yonggang Luo wrote:
> On Thu, Oct 8, 2026 at 5:42 PM Daniel P. Berrangé <[email protected]> wrote:
>>
>> On Wed, Oct 07, 2026 at 01:25:46PM -0700, Pierrick Bouvier wrote:
>>> On 10/7/2026 4:47 AM, Yonggang Luo wrote:
>>>> This allows a combined binary to register machine types from all its
>>>> targets.
>>>> Consequently, QMP `query-machines` can return machine entries from every
>>>> target, even when `none` is selected. For example, a client can query the
>>>> combined machine list with:
>>>>
>>>> ```json
>>>> { "execute": "query-machines" }
>>>> ```
>>>>
>>>> The returned list includes the registered machine classes from all linked
>>>> targets. This is separate from selecting a machine: with `-target none`,
>>>> `-M virt` reports the targets that provide `virt` instead of choosing one
>>>> arbitrarily:
>>>>
>>>> ```text
>>>> qemu-system -target none -M virt
>>>> unsupported machine type: "virt" for target "none"
>>>> Available for targets:
>>>> aarch64
>>>> arm
>>>> ```
>>>>
>>>
>>> From the long conversation on a previous thread, I thought we reached
>>> the conclusion that if we didn't expose any ambiguous name, then -target
>>> option is unnecessary, or maybe I got lost on track of this thread.
>>>
>>> https://lore.kernel.org/qemu-devel/[email protected]/
>>>
>>> I'm not sure which semantic we want to have with -target none. If there
>>> is no ambiguous name registered, we just don't need it at all. It's a
>>> win-win IMHO.
>>
>> Yes, if we expose unique names for every machine, then -target is then
>> redundant.
>
> so how to diff riscv32-virt and risv64-virt? oh so for this machine we
> needs two name?
> "virt" needs register twice for it? or register only a single time,
> but we prefix the target_name()
> automatically? for example machine::name === "virt", but we can use
> "riscv32-virt" "risv64-virt" to reach it?
>
Yes, ideally we should have different variant of virt for 32/64 bit.
Same goes for cpu max types.
QOM type is always registered unambiguously ("$arch-virt"). Then, for
the "alias" name, which is virt, in case multiple matches are found,
command line can return an error with list of unambiguous names to call it.
$ qemu-system -M virt
Multiple virt machines are available. Please choose one of them:
- aarch64-virt
- riscv64-virt
There is no "parsing" of the argument, it's just the real QOM type. Then
we can find which target it implements from mc->targets.
And then, we can automatically choose which cpus should be available
based on that, thanks to cpu->targets.
For existing binaries, nothing change.
>>
>> With regards,
>> Daniel
>> --
>> |: https://berrange.com ~~ https://hachyderm.io/@berrange :|
>> |: https://libvirt.org ~~ https://entangle-photo.org :|
>> |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|
>>
>
>
