Nice improvement!
> On Jun 29, 2017, at 9:23 AM, Marc-André Lureau <marcandre.lur...@redhat.com>
> wrote:
>
> This compat property sole function is to prevent the device from being
> instantiated. Instead of requiring an extra compat property, check if
> fw_cfg has DMA enabled.
>
> 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]
>
> Suggested-by: Eduardo Habkost <ehabk...@redhat.com>
> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
Reviewed-by: Ben Warren <b...@skyportsystems.com <mailto:m...@redhat.com>>
> ---
> include/hw/acpi/bios-linker-loader.h | 2 ++
> include/hw/compat.h | 4 ----
> hw/acpi/bios-linker-loader.c | 6 ++++++
> hw/acpi/vmgenid.c | 9 +--------
> 4 files changed, 9 insertions(+), 12 deletions(-)
>
> diff --git a/include/hw/acpi/bios-linker-loader.h
> b/include/hw/acpi/bios-linker-loader.h
> index efe17b0b9c..a711dbced8 100644
> --- a/include/hw/acpi/bios-linker-loader.h
> +++ b/include/hw/acpi/bios-linker-loader.h
> @@ -7,6 +7,8 @@ typedef struct BIOSLinker {
> GArray *file_list;
> } BIOSLinker;
>
> +bool bios_linker_loader_can_write_pointer(void);
> +
> BIOSLinker *bios_linker_loader_init(void);
>
> void bios_linker_loader_alloc(BIOSLinker *linker,
> diff --git a/include/hw/compat.h b/include/hw/compat.h
> index 26cd5851a5..36f02179ac 100644
> --- a/include/hw/compat.h
> +++ b/include/hw/compat.h
> @@ -150,10 +150,6 @@
> .driver = "fw_cfg_io",\
> .property = "dma_enabled",\
> .value = "off",\
> - },{\
> - .driver = "vmgenid",\
> - .property = "x-write-pointer-available",\
> - .value = "off",\
> },
>
> #define HW_COMPAT_2_3 \
> diff --git a/hw/acpi/bios-linker-loader.c b/hw/acpi/bios-linker-loader.c
> index 046183a0f1..587d62cb93 100644
> --- a/hw/acpi/bios-linker-loader.c
> +++ b/hw/acpi/bios-linker-loader.c
> @@ -168,6 +168,12 @@ bios_linker_find_file(const BIOSLinker *linker, const
> char *name)
> return NULL;
> }
>
> +bool bios_linker_loader_can_write_pointer(void)
> +{
> + FWCfgState *fw_cfg = fw_cfg_find();
> + return fw_cfg && fw_cfg_dma_enabled(fw_cfg);
> +}
> +
> /*
> * bios_linker_loader_alloc: ask guest to load file into guest memory.
> *
> diff --git a/hw/acpi/vmgenid.c b/hw/acpi/vmgenid.c
> index a32b847fe0..ab5da293fd 100644
> --- a/hw/acpi/vmgenid.c
> +++ b/hw/acpi/vmgenid.c
> @@ -205,17 +205,11 @@ static void vmgenid_handle_reset(void *opaque)
> memset(vms->vmgenid_addr_le, 0, ARRAY_SIZE(vms->vmgenid_addr_le));
> }
>
> -static Property vmgenid_properties[] = {
> - DEFINE_PROP_BOOL("x-write-pointer-available", VmGenIdState,
> - write_pointer_available, true),
> - DEFINE_PROP_END_OF_LIST(),
> -};
> -
> static void vmgenid_realize(DeviceState *dev, Error **errp)
> {
> VmGenIdState *vms = VMGENID(dev);
>
> - if (!vms->write_pointer_available) {
> + if (!bios_linker_loader_can_write_pointer()) {
> error_setg(errp, "%s requires DMA write support in fw_cfg, "
> "which this machine type does not provide",
> VMGENID_DEVICE);
> return;
> @@ -239,7 +233,6 @@ static void vmgenid_device_class_init(ObjectClass *klass,
> void *data)
> dc->vmsd = &vmstate_vmgenid;
> dc->realize = vmgenid_realize;
> dc->hotpluggable = false;
> - dc->props = vmgenid_properties;
>
> object_class_property_add_str(klass, VMGENID_GUID, NULL,
> vmgenid_set_guid, NULL);
> --
> 2.13.1.395.gf7b71de06
>
