Paolo Bonzini <pbonz...@redhat.com> writes:
> On 21/01/20 06:49, Markus Armbruster wrote:
>> Paolo Bonzini <pbonz...@redhat.com> writes:
>>
>>> On 13/01/20 15:01, Markus Armbruster wrote:
>>>> Philippe Mathieu-Daudé <phi...@redhat.com> writes:
>>>>
>>>>> When configured with --without-default-devices and setting
>>>>> MC146818RTC=n, the build fails:
>>>>>
>>>>> LINK x86_64-softmmu/qemu-system-x86_64
>>>>> /usr/bin/ld: qapi/qapi-commands-misc-target.o: in function
>>>>> `qmp_marshal_rtc_reset_reinjection':
>>>>> qapi/qapi-commands-misc-target.c:46: undefined reference to
>>>>> `qmp_rtc_reset_reinjection'
>>>>> /usr/bin/ld: qapi/qapi-commands-misc-target.c:46: undefined reference
>>>>> to `qmp_rtc_reset_reinjection'
>>>>> collect2: error: ld returned 1 exit status
>>>>> make[1]: *** [Makefile:206: qemu-system-x86_64] Error 1
>>>>> make: *** [Makefile:483: x86_64-softmmu/all] Error 2
>>>>>
>>>>> This patch tries to fix this, but this is incorrect because QAPI
>>>>> scripts only provide TARGET definitions, so with MC146818RTC=y we
>>>>> get:
>>>>>
>>>>> hw/rtc/mc146818rtc.c:113:6: error: no previous prototype for
>>>>> ‘qmp_rtc_reset_reinjection’ [-Werror=missing-prototypes]
>>>>> 113 | void qmp_rtc_reset_reinjection(Error **errp)
>>>>> | ^~~~~~~~~~~~~~~~~~~~~~~~~
>>>>> cc1: all warnings being treated as errors
>>>>> make[1]: *** [rules.mak:69: hw/rtc/mc146818rtc.o] Error 1
>>>>>
>>>>> Any idea? :)
>>>>>
>>>>> Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com>
>>>>> ---
>>>>> qapi/misc-target.json | 2 +-
>>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/qapi/misc-target.json b/qapi/misc-target.json
>>>>> index a00fd821eb..8e49c113d1 100644
>>>>> --- a/qapi/misc-target.json
>>>>> +++ b/qapi/misc-target.json
>>>>> @@ -41,7 +41,7 @@
>>>>> #
>>>>> ##
>>>>> { 'command': 'rtc-reset-reinjection',
>>>>> - 'if': 'defined(TARGET_I386)' }
>>>>> + 'if': 'defined(TARGET_I386) && defined(CONFIG_MC146818RTC)' }
>>>>>
>>>>>
>>>>> ##
>>>>
>>>> The generated qapi-commands-misc-target.h duly has
>>>>
>>>> #if defined(TARGET_I386) && defined(CONFIG_MC146818RTC)
>>>> void qmp_rtc_reset_reinjection(Error **errp);
>>>> void qmp_marshal_rtc_reset_reinjection(QDict *args, QObject **ret,
>>>> Error **errp);
>>>> #endif /* defined(TARGET_I386) && defined(CONFIG_MC146818RTC) */
>>>>
>>>> mc146818rtc.c includes it. But since it doesn't include
>>>> config-devices.h, CONFIG_MC146818RTC remains undefined, and the
>>>> prototype gets suppressed.
>>>>
>>>> Crude fix: make mc146818rtc.c #include "config-devices.h".
>>>
>>> Can we modify the code generator to leave out the #if from the header,
>>> and only include it in the .c file? An extra prototype is harmless.
>>
>> Is *everything* we generate into headers just as harmless?
>
> It should be, since it's just the C version of some JSON. The only
> problematic thing could be different definitions of the same command for
> multiple targets, and I think we want to avoid that anyway.
>
> To see it a different way, these are the "C bindings" to QMP, just that
> the implementation is an in-process call rather than RPC. If the QAPI
> code generator was also able to generate Python bindings and the like,
> they would have to be the same for all QEMU binaries, wouldn't they?
Ommitting the kind of #if we've been discussing is relatively harmless:
#if defined(TARGET_I386)
void qmp_rtc_reset_reinjection(Error **errp);
void qmp_marshal_rtc_reset_reinjection(QDict *args, QObject **ret, Error
**errp);
#endif /* defined(TARGET_I386) */
But what about this one, in qapi-types-block-core.h:
typedef enum BlockdevDriver {
BLOCKDEV_DRIVER_BLKDEBUG,
[...]
#if defined(CONFIG_REPLICATION)
BLOCKDEV_DRIVER_REPLICATION,
#endif /* defined(CONFIG_REPLICATION) */
[...]
BLOCKDEV_DRIVER__MAX,
} BlockdevDriver;
If I omit it in the header, I then have to omit it in
qapi-types-block-core.c's
const QEnumLookup BlockdevDriver_lookup = {
.array = (const char *const[]) {
[BLOCKDEV_DRIVER_BLKDEBUG] = "blkdebug",
[...]
#if defined(CONFIG_REPLICATION)
[BLOCKDEV_DRIVER_REPLICATION] = "replication",
#endif /* defined(CONFIG_REPLICATION) */
[...]
},
.size = BLOCKDEV_DRIVER__MAX
};
and God knows what else. But I must not omit it in qapi-introspect.c's
QLIT_QDICT(((QLitDictEntry[]) {
{ "meta-type", QLIT_QSTR("enum"), },
{ "name", QLIT_QSTR("245"), },
{ "values", QLIT_QLIST(((QLitObject[]) {
QLIT_QSTR("blkdebug"),
[...]
#if defined(CONFIG_REPLICATION)
QLIT_QSTR("replication"),
#endif /* defined(CONFIG_REPLICATION) */
[...]
{}
})), },
{}
})),
because that would defeat introspection.
I smell a swamp.
I'd rather not complicate the generator to support not including a
header I feel we *should* include. #ifdef CONFIG_FOO can occur not just
in QAPI-generated code, and neglecting to include the relevant header
can cause *nasty* problems not just in QAPI-generated code. Like
inconsistent struct definitions in separate compilation units. Been
there, debugged that, wasn't fun, do not want to go there again.
