Re: [Qemu-devel] [PATCH] Makefile: Move balloon.o, numa.o and bootdevice.o to common-obj-y

[Paolo Bonzini <pbonzini@redhat.com>]

On 14/06/2017 13:18, Thomas Huth wrote:
> On 08.06.2017 16:18, Thomas Huth wrote:
>> There does not seem to be any target specific code in these files, so
>> we can put them into "common-obj" instead of "obj" to compile them only
>> once for all targets.
> 
> Self-NACK: balloon.c uses kvm_enabled() which in turn depends on
> CONFIG_KVM ... and that flag is target-specific, so balloon.o can not be
> moved to common-obj right now.
> 
> We should poison CONFIG_KVM for common code ... I'll have a look into
> that...

No, your patch is okay.

#if defined CONFIG_KVM || !defined NEED_CPU_H
#define kvm_enabled()           (kvm_allowed)
...
#else
#define kvm_enabled()           (0)

In other words, kvm_enabled() forces itself to be 0 only in per-target
files.  This is done mostly to limit the number of required stubs:
target-independent APIs can be called from compile-once files and must
be stubbed; target-specific APIs can only be called from per-target
files, and their calls are culled by the compiler if !CONFIG_KVM.

Paolo