hw/i386: Add the ramfb romfile compatibility

ramfb is a sysbus device so it can only used for machine types where it
is explicitly enabled:

  # git grep machine_class_allow_dynamic_sysbus_dev.*TYPE_RAMFB_DEVICE
  hw/arm/virt.c:    machine_class_allow_dynamic_sysbus_dev(mc,
		  TYPE_RAMFB_DEVICE);
  hw/i386/microvm.c:    machine_class_allow_dynamic_sysbus_dev(mc,
		  TYPE_RAMFB_DEVICE);
  hw/i386/pc_piix.c:    machine_class_allow_dynamic_sysbus_dev(m,
		  TYPE_RAMFB_DEVICE);
  hw/i386/pc_q35.c:    machine_class_allow_dynamic_sysbus_dev(m,
		  TYPE_RAMFB_DEVICE);
  hw/loongarch/virt.c:    machine_class_allow_dynamic_sysbus_dev(mc,
		  TYPE_RAMFB_DEVICE);
  hw/riscv/virt.c:    machine_class_allow_dynamic_sysbus_dev(mc,
		  TYPE_RAMFB_DEVICE);

So these six are the only machine types we have to worry about.

The three x86 machine types (pc, q35, microvm) will actually use the rom
(when booting with seabios).

For arm/riscv/loongarch virt we want to disable the rom.

This patch sets ramfb romfile option to false by default, except for x86
machines types (pc, q35, microvm) which need the rom file when booting
with seabios and machine types <= 10.0 (handling the case of arm virt,
for compat reasons).

At the same time, set the "use-legacy-x86-rom" property to true on those
historical versioned machine types in order to avoid the memory layout
being changed.

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Shaoqin Huang <shahuang@redhat.com>
Message-ID: <20250717100941.2230408-4-shahuang@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

0 files changed, 0 insertions, 0 deletions