On 12/11/2013 06:18 AM, Michal Privoznik wrote:
>
> I'm getting some compile errors on ARM:
>
> CC conf/libvirt_conf_la-domain_event.lo
> conf/domain_event.c: In function 'virDomainEventDispatchDefaultFunc':
> conf/domain_event.c:1148:30: error: cast increases required alignment of
> target type [-Werror=cast-align]
> rtcChangeEvent = (virDomainEventRTCChangePtr)event;
Hmm. In this case, event is virObjectEventPtr, and rtcChangeEvent is
virDomainEventRTCChangePtr. Comparing the two structs, I see the problem:
struct _virObjectEvent {
virObject parent;
int eventID;
virObjectMeta meta;
};
Only has alignment specified by virObject (which in turn is unsigned
int, int, void*), int, and virObjectMeta (which in turn is int, char*,
unsigned char[]).
vs.
struct _virDomainEventRTCChange {
virDomainEvent parent;
long long offset;
};
I think one possible solution would be as simple as altering
src/util/virobject.h to change 'magic' from 'unsigned int' to 'unsigned
long long' - then ALL virObject structs will be forcefully aligned to
the worst case between void* and long long, so that any subclass can use
long long without requiring stricter alignment than the parent class,
and so that downcasting code like domain_event.c no longer warns. But
it does make every object consume more memory on 64-bit platforms (from
16 bytes into 24 bytes), is that okay?
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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