On Mon, Apr 24, 2017 at 05:03:55PM +0400, Marc-André Lureau wrote:
[...]
> diff --git a/include/hw/compat.h b/include/hw/compat.h
> index 5d5be91daf..d0c9b71902 100644
> --- a/include/hw/compat.h
> +++ b/include/hw/compat.h
> @@ -135,6 +135,10 @@
> .driver = "vmgenid",\
> .property = "x-write-pointer-available",\
> .value = "off",\
> + },{\
> + .driver = "vmcoreinfo",\
> + .property = "x-write-pointer-available",\
> + .value = "off",\
> },
My first reaction to this was "we don't need this compat property, because the
device didn't even exist in QEMU 2.4".
But then I read commit f2a1ae45d8ec5ad494e66a9234499a2e0fbf4b40 and now I see
why this is required: this is a compat property whose sole function is to
prevent the device from being instantiated.
Instead of requiring an extra compat property, I suggest just checking if
fw_cfg has DMA enabled. e.g.:
static void vmgenid_realize(DeviceState *dev, Error **errp)
{
VmGenIdState *vms = VMGENID(dev);
+ FWCfgState *fw_cfg = FW_CFG(object_resolve_path_type("", TYPE_FW_CFG,
NULL));
- if (!vms->write_pointer_available) {
+ if (!fw_cfg || !fw_cfg_dma_enabled(fw_cfg)) {
error_setg(errp, "%s requires DMA write support in fw_cfg, "
"which this machine type does not provide", VMGENID_DEVICE);
return;
This has the additional benefit of handling other cases properly, like:
$ qemu-system-x86_64 -device vmgenid -machine none
qemu-system-x86_64: -device vmgenid: vmgenid requires DMA write support in
fw_cfg, which this machine type does not provide
$ qemu-system-x86_64 -device vmgenid -machine pc-i440fx-2.9 -global
fw_cfg.dma_enabled=off
qemu-system-x86_64: -device vmgenid: vmgenid requires DMA write support in
fw_cfg, which this machine type does not provide
$ qemu-system-x86_64 -device vmgenid -machine pc-i440fx-2.6 -global
fw_cfg.dma_enabled=on
[boots normally]
$
--
Eduardo
