Re: [Qemu-devel] [PATCH] Makefile: Don't build generated headers before Makefile is reread

[Paolo Bonzini <pbonzini@redhat.com>]

Il 04/07/2014 16:33, Peter Maydell ha scritto:
> On 30 June 2014 13:09, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> Il 28/06/2014 18:59, Peter Maydell ha scritto:
>>
>>> Having a direct dependency
>>>    Makefile: $(GENERATED_HEADERS)
>>> can result in not-from-clean builds failing sometimes, because it means
>>> that when Make does its "is any makefile or include out of date and
>>> needing a rebuild?" check, as well as possibly running configure (to
>>> update config-host.mak) it will also rebuild GENERATED_HEADERS under
>>> the "old" config-host.mak regime. If the makefile rules for rebuilding
>>> the generated headers have changed in a way that means they're not
>>> compatible with the old config-host.mak variable names, the build will
>>> fail. Even if it does work, it's wasted effort since we'll need to
>>> rebuild them with the right config-host.mak settings immediately.
>>>
>>> Instead, make the generated headers depend on config-host.mak
>>> and config-target.mak. This means we'll definitely rebuild them
>>> if the configuration changes, but it will be done after Make
>>> reloads its makefiles and includes so will happen with the
>>> correct set of config-host.mak settings.
>>>
>>> We rely on the various .o files having correct autogenerated
>>> dependency rules to cause the generated headers to be generated
>>> as and when they are needed.
>
>> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
>
>
> Any objections to this going into 2.1 for rc1 ?

Not from me.

Paolo