Am 21.08.2013 23:05, schrieb Peter Maydell:
> On 20 August 2013 16:21, Andreas Färber <afaer...@suse.de> wrote:
>> From: Andreas Färber <andreas.faer...@web.de>
>>
>> This covers both emulated and KVM GIC.
>
>> @@ -35,40 +36,48 @@ typedef struct A15MPPrivState {
>> uint32_t num_cpu;
>> uint32_t num_irq;
>> MemoryRegion container;
>> - DeviceState *gic;
>> +
>> + GICState gic;
>> } A15MPPrivState;
>
>> static void a15mp_priv_initfn(Object *obj)
>> {
>> SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
>> A15MPPrivState *s = A15MPCORE_PRIV(obj);
>> + DeviceState *gicdev;
>> + const char *gictype = "arm_gic";
>> +
>> + if (kvm_irqchip_in_kernel()) {
>> + gictype = "kvm-arm-gic";
>> + }
>>
>> memory_region_init(&s->container, obj, "a15mp-priv-container", 0x8000);
>> sysbus_init_mmio(sbd, &s->container);
>> +
>> + object_initialize(&s->gic, gictype);
>> + gicdev = DEVICE(&s->gic);
>> + qdev_set_parent_bus(gicdev, sysbus_get_default());
>> + qdev_prop_set_uint32(gicdev, "revision", 2);
>
> So this is basically assuming that kvm-arm-gic and arm-gic
> both have an instance struct of exactly the same size,
> even though they're different classes (they happen to be
> so at the moment, because neither adds extra state beyond
> that needed by common base class). Is that really a good
> idea? (If it ever becomes not true we get silent memory
> corruption here...)
Not sure if a union of only one member is permitted? We're not actually
accessing the GICState, only void* and DEVICE()/SYS_BUS_DEVICE(), so it
just needs to block the memory, hopefully without needing to distinguish
between ->gic.emulated and ->gic.kvm pointers.
The decision doesn't depend on any user-settable property, just on the
at this point global kvm_enabled() state, so I see nowhere else to
allocate it dynamically.
If you change the .instance_size struct one of the GICs uses, then a
number of places will need to be reviewed, including
ARM_GIC_COMMON()[*], ARM_GIC() and KVM_ARM_GIC() all returning the same
type.
[*] When we're through with the functional changes, we should
s/ARM_GIC_COMMON/COMMON_ARM_GIC/g to match the general pattern.
Andreas
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