vmgenid: replace x-write-pointer-available hack

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.

fw_cfg is a built-in device that is initialized very early by the
machine init code.  We have at least one other device that also
assumes fw_cfg_find() can be safely used on realize: pvpanic.

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 <ehabkost@redhat.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Ben Warren <ben@skyportsystems.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Marc-André Lureau 2017-08-07 18:45:13 +02:00 committed by Michael S. Tsirkin
parent 672339f7ef
commit c8389550de
5 changed files with 13 additions and 13 deletions

View file

@ -153,10 +153,6 @@
.driver = "fw_cfg_io",\
.property = "dma_enabled",\
.value = "off",\
},{\
.driver = "vmgenid",\
.property = "x-write-pointer-available",\
.value = "off",\
},
#define HW_COMPAT_2_3 \