Re: [PATCH v7 2/2] hw/i386: Add the ramfb romfile compatibility

[Shaoqin Huang]

Hi Eric,

On 7/2/25 5:08 PM, Eric Auger wrote:


On 7/2/25 10:56 AM, Shaoqin Huang wrote:
Set the "use-legacy-x86-rom" property to false by default, and only set
it to true on x86 since only x86 will need it.

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.

Signed-off-by: Shaoqin Huang <shahu...@redhat.com>
---
  hw/core/machine.c             |  2 ++
  hw/display/ramfb-standalone.c |  2 +-
  hw/i386/pc_piix.c             | 10 ++++++++++
  hw/i386/pc_q35.c              |  3 +++
If I understood correctly, Gerd said we needed to set the prop to "true"
on microvm too? I don't see that change.

Yes, I try to do that. But I didn't see there are any machine type in 
the microvm like q35. I'm confuse about it, How should I do that?

Thanks,
Shaoqin


Eric
  hw/vfio/pci.c                 |  2 +-
  5 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index e869821b22..a7043e2a34 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -39,6 +39,8 @@
  
  GlobalProperty hw_compat_10_0[] = {
      { "scsi-hd", "dpofua", "off" },
+    { "ramfb", "use-legacy-x86-rom", "true"},
+    { "vfio-pci", "use-legacy-x86-rom", "true" },
  };
  const size_t hw_compat_10_0_len = G_N_ELEMENTS(hw_compat_10_0);
  
diff --git a/hw/display/ramfb-standalone.c b/hw/display/ramfb-standalone.c
index 725aef9896..b20a7c57b3 100644
--- a/hw/display/ramfb-standalone.c
+++ b/hw/display/ramfb-standalone.c
@@ -63,7 +63,7 @@ static const VMStateDescription ramfb_dev_vmstate = {
  
  static const Property ramfb_properties[] = {
      DEFINE_PROP_BOOL("x-migrate", RAMFBStandaloneState, migrate,  true),
-    DEFINE_PROP_BOOL("use-legacy-x86-rom", RAMFBStandaloneState, 
use_legacy_x86_rom, true),
+    DEFINE_PROP_BOOL("use-legacy-x86-rom", RAMFBStandaloneState, 
use_legacy_x86_rom, false),
  };
  
  static void ramfb_class_initfn(ObjectClass *klass, const void *data)
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index ea7572e783..8ec8d8ae6d 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -49,6 +49,7 @@
  #include "hw/i2c/smbus_eeprom.h"
  #include "system/memory.h"
  #include "hw/acpi/acpi.h"
+#include "hw/vfio/pci.h"
  #include "qapi/error.h"
  #include "qemu/error-report.h"
  #include "system/xen.h"
@@ -77,6 +78,13 @@ static const int ide_iobase2[MAX_IDE_BUS] = { 0x3f6, 0x376 };
  static const int ide_irq[MAX_IDE_BUS] = { 14, 15 };
  #endif
  
+static GlobalProperty pc_piix_compat_defaults[] = {
+    { TYPE_RAMFB_DEVICE, "use-legacy-x86-rom", "true" },
+    { TYPE_VFIO_PCI, "use-legacy-x86-rom", "true" },
+};
+static const size_t pc_piix_compat_defaults_len =
+    G_N_ELEMENTS(pc_piix_compat_defaults);
+
  /*
   * Return the global irq number corresponding to a given device irq
   * pin. We could also use the bus number to have a more precise mapping.
@@ -482,6 +490,8 @@ static void pc_i440fx_machine_options(MachineClass *m)
                                     pc_set_south_bridge);
      object_class_property_set_description(oc, "x-south-bridge",
                                       "Use a different south bridge than 
PIIX3");
+    compat_props_add(m->compat_props,
+                     pc_piix_compat_defaults, pc_piix_compat_defaults_len);
  }
  
  static void pc_i440fx_machine_10_1_options(MachineClass *m)
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 33211b1876..0096eef6f4 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -45,6 +45,7 @@
  #include "hw/i386/pc.h"
  #include "hw/i386/amd_iommu.h"
  #include "hw/i386/intel_iommu.h"
+#include "hw/vfio/pci.h"
  #include "hw/virtio/virtio-iommu.h"
  #include "hw/display/ramfb.h"
  #include "hw/ide/pci.h"
@@ -67,6 +68,8 @@
  
  static GlobalProperty pc_q35_compat_defaults[] = {
      { TYPE_VIRTIO_IOMMU_PCI, "aw-bits", "39" },
+    { TYPE_RAMFB_DEVICE, "use-legacy-x86-rom", "true" },
+    { TYPE_VFIO_PCI, "use-legacy-x86-rom", "true" },
  };
  static const size_t pc_q35_compat_defaults_len =
      G_N_ELEMENTS(pc_q35_compat_defaults);
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index f4fa8a5610..604b337389 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3710,7 +3710,7 @@ static const TypeInfo vfio_pci_dev_info = {
  
  static const Property vfio_pci_dev_nohotplug_properties[] = {
      DEFINE_PROP_BOOL("ramfb", VFIOPCIDevice, enable_ramfb, false),
-    DEFINE_PROP_BOOL("use-legacy-x86-rom", VFIOPCIDevice, use_legacy_x86_rom, 
true),
+    DEFINE_PROP_BOOL("use-legacy-x86-rom", VFIOPCIDevice, use_legacy_x86_rom, 
false),
      DEFINE_PROP_ON_OFF_AUTO("x-ramfb-migrate", VFIOPCIDevice, ramfb_migrate,
                              ON_OFF_AUTO_AUTO),
  };


--
Shaoqin