Re: [PATCH v4 46/55] qapi: add query-targets

["Philippe Mathieu-Daudé" <philmd@oss.qualcomm.com>]

On 28/9/26 12:51, Yonggang Luo wrote:
> On Mon, Sep 28, 2026 at 6:39 PM Philippe Mathieu-Daudé <
> philmd@oss.qualcomm.com> wrote:
>>
>> On 28/9/26 12:13, Daniel P. Berrangé wrote:
>>> On Sat, Sep 26, 2026 at 03:00:45PM +0800, Yonggang Luo wrote:
>>>> query-targets lists each linked target, including none, with its
>>>> arch, endianness, and the machines that target accepts.
>>>>
>>>> Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
>>>> ---
>>>>    hw/core/machine-qmp-cmds.c | 30 ++++++++++++++++++++++++++++++
>>>>    qapi/machine.json          | 35 +++++++++++++++++++++++++++++++++++
>>>>    2 files changed, 65 insertions(+)
>>>
>>>
>>>> diff --git a/qapi/machine.json b/qapi/machine.json
>>>> index 6aaa2af709a..d8cdea6203e 100644
>>>> --- a/qapi/machine.json
>>>> +++ b/qapi/machine.json
>>>> @@ -307,6 +307,41 @@
>>>>    ##
>>>>    { 'command': 'query-target', 'returns': 'QemuTargetInfo' }
>>>>
>>>> +##
>>>> +# @TargetMachines:
>>>> +#
>>>> +# One registered system target and the machines that can run on it.
>>>> +#
>>>> +# @arch: the target architecture
>>>> +#
>>>> +# @endianness: the target endianness
>>>> +#
>>>> +# @machines: machine type names, not aliases
>>>> +#
>>>> +# Since: 11.2
>>>> +##
>>>> +{ 'struct': 'TargetMachines',
>>>> +  'data': { 'arch': 'SysEmuTarget',
>>>> +            'endianness': 'EndianMode',
>>>> +            'machines': ['str'] } }
>>>
>>> We already have  'QemuTargetInfo' struct which is used
>>> with 'query-target', that should also be used with the
>>> new 'query-targets' command.
>>>
>>> We need to add the 'endianness' field to QemuTargetInfo.
>>
>> Why do we want to expose endianness, and what endianness to
>> expose? Endianness is a runtime bit state of CPUs. Sometime
>> this bit is hardwired but that is an implementation detail.
> 
> For some targets it's, but for some targets it's not. for example
> 
> mips-softmmu.mak
> mipsel-softmmu.mak
> mips64el-softmmu.mak
> mips64-softmmu.mak
> 
> 
> mips64el-softmmu.mak
> mips64-softmmu.mak
> only differ the endianless
If you look at git / mailing list history you'll see I spent more
than a year unifying QEMU endianness. It was too much work for a
single person so we decided to reduce the scope to ARM + MicroBlaze
for single binary and we got MicroBlaze unified. We don't want
an endianness-specific single binary. I'm not sure what you are
trying to build, you didn't clearly explained what is your goal here.

You can find series unifying endianness for MIPS, not merged because
more things need to be addressed and not the priority.