On 3/19/20 10:36 AM, Paolo Bonzini wrote:
On 18/03/20 23:15, Philippe Mathieu-Daudé wrote:
The I/O ranges registered by the piix4_acpi_system_hot_add_init()
function are not documented in the PIIX4 datasheet.
This appears to be a PC-only feature added in commit 5e3cb5347e
("initialize hot add system / acpi gpe") which was then moved
to the PIIX4 device model in commit 9d5e77a22f ("make
qemu_system_device_hot_add piix independent")
Add a property (default enabled, to not modify the current
behavior) to allow machines wanting to model a simple PIIX4
to disable this feature.
Yes, all hotplug stuff (PCI/memory/CPU) are custom additions by QEMU.
+ DEFINE_PROP_BOOL("system-hotplug-support", PIIX4PMState,
+ use_acpi_system_hotplug, true),
Why not cpu-hotplug-support?
Because I have no idea what this code is about, and it seems more than
cpu (pci, memory):
static void piix4_acpi_system_hot_add_init(MemoryRegion *parent,
PCIBus *bus, PIIX4PMState *s)
{
memory_region_init_io(&s->io_gpe, OBJECT(s), &piix4_gpe_ops, s,
"acpi-gpe0", GPE_LEN);
memory_region_add_subregion(parent, GPE_BASE, &s->io_gpe);
acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent,
s->use_acpi_pci_hotplug);
s->cpu_hotplug_legacy = true;
object_property_add_bool(OBJECT(s), "cpu-hotplug-legacy",
piix4_get_cpu_hotplug_legacy,
piix4_set_cpu_hotplug_legacy,
NULL);
legacy_acpi_cpu_hotplug_init(parent, OBJECT(s), &s->gpe_cpu,
PIIX4_CPU_HOTPLUG_IO_BASE);
if (s->acpi_memory_hotplug.is_enabled) {
acpi_memory_hotplug_init(parent, OBJECT(s),
&s->acpi_memory_hotplug,
ACPI_MEMORY_HOTPLUG_BASE);
}
}