Re: [PATCH 10/13] qapi: add weak stubs for target specific commands

[Pierrick Bouvier <pierrick.bouvier@linaro.org>]

On 5/7/25 11:57 PM, Philippe Mathieu-Daudé wrote:
> On 8/5/25 01:14, Pierrick Bouvier wrote:
>> We are about to expose various target specific commands for all targets,
>> so we need to stub not implemented qmp_* functions.
>>
>> MinGW does not support weak symbols without at least one strong
>> definition, so we'll have to detail stubs per target. Sad.
>>
>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>> ---
>>    qapi/commands-weak-stubs.c | 38 ++++++++++++++++++++++++++++++++++++++
>>    qapi/meson.build           |  2 ++
>>    2 files changed, 40 insertions(+)
>>    create mode 100644 qapi/commands-weak-stubs.c
>>
>> diff --git a/qapi/commands-weak-stubs.c b/qapi/commands-weak-stubs.c
>> new file mode 100644
>> index 00000000000..9734263c32e
>> --- /dev/null
>> +++ b/qapi/commands-weak-stubs.c
>> @@ -0,0 +1,38 @@
>> +/*
>> + * Weak symbols for target specific commands
>> + *
>> + * Copyright Linaro, 2025
>> + *
>> + * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
>> + * See the COPYING.LIB file in the top-level directory.
>> + *
>> + */
>> +
>> +#include "qemu/osdep.h"
>> +#include <glib.h>
>> +
>> +#define NOT_REACHABLE(symbol)                                                  \
>> +void __attribute__((weak)) symbol(void);                                       \
>> +void __attribute__((weak)) symbol(void) { g_assert_not_reached(); }
>> +
>> +#define WEAK_STUB(command)                                                     \
>> +NOT_REACHABLE(qmp_marshal_##command)                                           \
>> +NOT_REACHABLE(qmp_##command)
>> +
>> +WEAK_STUB(query_cpu_model_comparison);
>> +WEAK_STUB(query_cpu_model_baseline);
>> +WEAK_STUB(set_cpu_topology);
>> +WEAK_STUB(query_s390x_cpu_polarization);
>> +WEAK_STUB(rtc_reset_reinjection);
>> +WEAK_STUB(query_sev);
>> +WEAK_STUB(query_sev_launch_measure);
>> +WEAK_STUB(query_sev_capabilities);
>> +WEAK_STUB(sev_inject_launch_secret);
>> +WEAK_STUB(query_sev_attestation_report);
>> +WEAK_STUB(query_sgx);
>> +WEAK_STUB(query_sgx_capabilities);
>> +WEAK_STUB(xen_event_list);
>> +WEAK_STUB(xen_event_inject);
>> +WEAK_STUB(query_cpu_model_expansion);
>> +WEAK_STUB(query_cpu_definitions);
>> +WEAK_STUB(query_gic_capabilities);
> 
> Shouldn't this also be generated by QAPI scripts?
> 

It's a bit tricky, because we would need to generate the build system 
also (which targets links what), and meson is a sane tool so it prevents 
users from doing that.

>> diff --git a/qapi/meson.build b/qapi/meson.build
>> index eadde4db307..60fc958ec10 100644
>> --- a/qapi/meson.build
>> +++ b/qapi/meson.build
>> @@ -147,3 +147,5 @@ foreach output : qapi_specific_outputs + qapi_nonmodule_outputs
>>      specific_ss.add(when: 'CONFIG_SYSTEM_ONLY', if_true: qapi_files[i])
>>      i = i + 1
>>    endforeach
>> +
>> +system_ss.add(files('commands-weak-stubs.c'))
>