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[PATCH v4 2/2] hw/i386: Add the ramfb romfile compatatibility

Shaoqin Huang posted 2 patches 5 months ago
Maintainers: Gerd Hoffmann <kraxel@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Eduardo Habkost <eduardo@habkost.net>, Alex Williamson <alex.williamson@redhat.com>, "Cédric Le Goater" <clg@redhat.com>
There is a newer version of this series
[PATCH v4 2/2] hw/i386: Add the ramfb romfile compatatibility
Posted by Shaoqin Huang 5 months ago 
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.

Signed-off-by: Shaoqin Huang <shahuang@redhat.com>
---
 hw/display/ramfb-standalone.c | 2 +-
 hw/i386/pc_q35.c              | 3 +++
 hw/vfio/pci.c                 | 2 +-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/hw/display/ramfb-standalone.c b/hw/display/ramfb-standalone.c
index af1175bf96..ddbf42f181 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, void *data)
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index fd96d0345c..f6d89578d0 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 ff0d93fae0..a529500b70 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3564,7 +3564,7 @@ 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),
 };
-- 
2.40.1
Re: [PATCH v4 2/2] hw/i386: Add the ramfb romfile compatatibility
Posted by Eric Auger 4 months, 3 weeks ago 

On 6/17/25 5:05 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.
s/compatatibility/compatibility in the title
> 
> Signed-off-by: Shaoqin Huang <shahuang@redhat.com>
> ---
>  hw/display/ramfb-standalone.c | 2 +-
>  hw/i386/pc_q35.c              | 3 +++
>  hw/vfio/pci.c                 | 2 +-
>  3 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/display/ramfb-standalone.c b/hw/display/ramfb-standalone.c
> index af1175bf96..ddbf42f181 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, void *data)
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index fd96d0345c..f6d89578d0 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" },
this will only keep the legacy behavior along with q35 machine type but
not on other machines being used for x86. what about pc-i440fx? Doesn't
it apply to it as well? Are there other machine types also impacted.

Also what about Daniel's comment in v3:
https://lore.kernel.org/all/aEak8utPPkHepVfR@redhat.com/
"For non-x86, historical versioned machine types will need
likely it set to true, in order to avoid the memory layout
being changed IIUC."

Is it actually needed?

Thanks

Eric
>  };
>  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 ff0d93fae0..a529500b70 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -3564,7 +3564,7 @@ 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),
>  };
Re: [PATCH v4 2/2] hw/i386: Add the ramfb romfile compatatibility
Posted by Shaoqin Huang 4 months, 3 weeks ago 
Hi Eric,

On 6/23/25 5:20 PM, Eric Auger wrote:
> 
> 
> On 6/17/25 5:05 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.
> s/compatatibility/compatibility in the title

Ok. Will fix it.

>>
>> Signed-off-by: Shaoqin Huang <shahuang@redhat.com>
>> ---
>>   hw/display/ramfb-standalone.c | 2 +-
>>   hw/i386/pc_q35.c              | 3 +++
>>   hw/vfio/pci.c                 | 2 +-
>>   3 files changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/display/ramfb-standalone.c b/hw/display/ramfb-standalone.c
>> index af1175bf96..ddbf42f181 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, void *data)
>> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
>> index fd96d0345c..f6d89578d0 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" },
> this will only keep the legacy behavior along with q35 machine type but
> not on other machines being used for x86. what about pc-i440fx? Doesn't
> it apply to it as well? Are there other machine types also impacted.

Ok I will also add it with pc-i440fx. I think only q35 and i440fx are 
impacted.

> 
> Also what about Daniel's comment in v3:
> https://lore.kernel.org/all/aEak8utPPkHepVfR@redhat.com/
> "For non-x86, historical versioned machine types will need
> likely it set to true, in order to avoid the memory layout
> being changed IIUC."
> 
> Is it actually needed?

If those machine types need to set it to true. I think they can set it 
after they have this property.

Thanks,
Shaoqin

> 
> Thanks
> 
> Eric
>>   };
>>   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 ff0d93fae0..a529500b70 100644
>> --- a/hw/vfio/pci.c
>> +++ b/hw/vfio/pci.c
>> @@ -3564,7 +3564,7 @@ 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
Re: [PATCH v4 2/2] hw/i386: Add the ramfb romfile compatatibility
Posted by Eric Auger 4 months, 3 weeks ago 

On 6/26/25 4:05 AM, Shaoqin Huang wrote:
> Hi Eric,
> 
> On 6/23/25 5:20 PM, Eric Auger wrote:
>>
>>
>> On 6/17/25 5:05 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.
>> s/compatatibility/compatibility in the title
> 
> Ok. Will fix it.
> 
>>>
>>> Signed-off-by: Shaoqin Huang <shahuang@redhat.com>
>>> ---
>>>   hw/display/ramfb-standalone.c | 2 +-
>>>   hw/i386/pc_q35.c              | 3 +++
>>>   hw/vfio/pci.c                 | 2 +-
>>>   3 files changed, 5 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/hw/display/ramfb-standalone.c b/hw/display/ramfb-
>>> standalone.c
>>> index af1175bf96..ddbf42f181 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, void *data)
>>> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
>>> index fd96d0345c..f6d89578d0 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" },
>> this will only keep the legacy behavior along with q35 machine type but
>> not on other machines being used for x86. what about pc-i440fx? Doesn't
>> it apply to it as well? Are there other machine types also impacted.
> 
> Ok I will also add it with pc-i440fx. I think only q35 and i440fx are
> impacted.
> 
>>
>> Also what about Daniel's comment in v3:
>> https://lore.kernel.org/all/aEak8utPPkHepVfR@redhat.com/
>> "For non-x86, historical versioned machine types will need
>> likely it set to true, in order to avoid the memory layout
>> being changed IIUC."
>>
>> Is it actually needed?
> 
> If those machine types need to set it to true. I think they can set it
> after they have this property.
nope it does not work like that. In case we really need to take care of
this, this must be handled by compats.

Thanks

Eric
> 
> Thanks,
> Shaoqin
> 
>>
>> Thanks
>>
>> Eric
>>>   };
>>>   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 ff0d93fae0..a529500b70 100644
>>> --- a/hw/vfio/pci.c
>>> +++ b/hw/vfio/pci.c
>>> @@ -3564,7 +3564,7 @@ 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),
>>>   };
>>
>
Re: [PATCH v4 2/2] hw/i386: Add the ramfb romfile compatatibility
Posted by Gerd Hoffmann 4 months, 2 weeks ago 
  Hi,

> > If those machine types need to set it to true. I think they can set it
> > after they have this property.
> nope it does not work like that. In case we really need to take care of
> this, this must be handled by compats.

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 disable the rom.

Everything else doesn't matter much because ramfb can not be used in the
first place, you'll get an error like this when trying:

  # qemu-default -M isapc -device ramfb
  qemu-system-x86_64: -device ramfb: Parameter 'driver' expects a dynamic sysbus device type for the machine

HTH & take care,
  Gerd
Re: [PATCH v4 2/2] hw/i386: Add the ramfb romfile compatatibility
Posted by Eric Auger 4 months, 2 weeks ago 
Hi Gerd,

On 7/1/25 2:04 PM, Gerd Hoffmann wrote:
>   Hi,
> 
>>> If those machine types need to set it to true. I think they can set it
>>> after they have this property.
>> nope it does not work like that. In case we really need to take care of
>> this, this must be handled by compats.
> 
> 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).
makes total sense. So microvm is needed as well.

Thank you for the confirmation!

Eric
> 
> For arm/riscv/loongarch virt we want disable the rom.
> 
> Everything else doesn't matter much because ramfb can not be used in the
> first place, you'll get an error like this when trying:
> 
>   # qemu-default -M isapc -device ramfb
>   qemu-system-x86_64: -device ramfb: Parameter 'driver' expects a dynamic sysbus device type for the machine
> 
> HTH & take care,
>   Gerd
>
Re: [PATCH v4 2/2] hw/i386: Add the ramfb romfile compatatibility
Posted by Shaoqin Huang 4 months, 3 weeks ago 
Hi Eric,

On 6/26/25 4:01 PM, Eric Auger wrote:
> 
> 
> On 6/26/25 4:05 AM, Shaoqin Huang wrote:
>> Hi Eric,
>>
>> On 6/23/25 5:20 PM, Eric Auger wrote:
>>>
>>>
>>> On 6/17/25 5:05 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.
>>> s/compatatibility/compatibility in the title
>>
>> Ok. Will fix it.
>>
>>>>
>>>> Signed-off-by: Shaoqin Huang <shahuang@redhat.com>
>>>> ---
>>>>    hw/display/ramfb-standalone.c | 2 +-
>>>>    hw/i386/pc_q35.c              | 3 +++
>>>>    hw/vfio/pci.c                 | 2 +-
>>>>    3 files changed, 5 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/hw/display/ramfb-standalone.c b/hw/display/ramfb-
>>>> standalone.c
>>>> index af1175bf96..ddbf42f181 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, void *data)
>>>> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
>>>> index fd96d0345c..f6d89578d0 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" },
>>> this will only keep the legacy behavior along with q35 machine type but
>>> not on other machines being used for x86. what about pc-i440fx? Doesn't
>>> it apply to it as well? Are there other machine types also impacted.
>>
>> Ok I will also add it with pc-i440fx. I think only q35 and i440fx are
>> impacted.
>>
>>>
>>> Also what about Daniel's comment in v3:
>>> https://lore.kernel.org/all/aEak8utPPkHepVfR@redhat.com/
>>> "For non-x86, historical versioned machine types will need
>>> likely it set to true, in order to avoid the memory layout
>>> being changed IIUC."
>>>
>>> Is it actually needed?
>>
>> If those machine types need to set it to true. I think they can set it
>> after they have this property.
> nope it does not work like that. In case we really need to take care of
> this, this must be handled by compats.

If so. Why don't we still keep the "use-legacy-x86-rom" default to true, 
and only set it to false to those arch which doesn't need it just like 
my original implementation.

Because I don't really know how other arch's memoery layout was impacted 
by this property set to false. I think keep their original behavior and 
only change it on arm64 is a good idea.

How do you think about it?

Thanks,
Shaoqin

> 
> Thanks
> 
> Eric
>>
>> Thanks,
>> Shaoqin
>>
>>>
>>> Thanks
>>>
>>> Eric
>>>>    };
>>>>    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 ff0d93fae0..a529500b70 100644
>>>> --- a/hw/vfio/pci.c
>>>> +++ b/hw/vfio/pci.c
>>>> @@ -3564,7 +3564,7 @@ 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
Re: [PATCH v4 2/2] hw/i386: Add the ramfb romfile compatatibility
Posted by Daniel P. Berrangé 4 months, 3 weeks ago 
On Fri, Jun 27, 2025 at 01:37:55PM +0800, Shaoqin Huang wrote:
> Hi Eric,
> 
> On 6/26/25 4:01 PM, Eric Auger wrote:
> > 
> > 
> > On 6/26/25 4:05 AM, Shaoqin Huang wrote:
> > > Hi Eric,
> > > 
> > > On 6/23/25 5:20 PM, Eric Auger wrote:
> > > > 
> > > > 
> > > > On 6/17/25 5:05 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.
> > > > s/compatatibility/compatibility in the title
> > > 
> > > Ok. Will fix it.
> > > 
> > > > > 
> > > > > Signed-off-by: Shaoqin Huang <shahuang@redhat.com>
> > > > > ---
> > > > >    hw/display/ramfb-standalone.c | 2 +-
> > > > >    hw/i386/pc_q35.c              | 3 +++
> > > > >    hw/vfio/pci.c                 | 2 +-
> > > > >    3 files changed, 5 insertions(+), 2 deletions(-)
> > > > > 
> > > > > diff --git a/hw/display/ramfb-standalone.c b/hw/display/ramfb-
> > > > > standalone.c
> > > > > index af1175bf96..ddbf42f181 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, void *data)
> > > > > diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> > > > > index fd96d0345c..f6d89578d0 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" },
> > > > this will only keep the legacy behavior along with q35 machine type but
> > > > not on other machines being used for x86. what about pc-i440fx? Doesn't
> > > > it apply to it as well? Are there other machine types also impacted.
> > > 
> > > Ok I will also add it with pc-i440fx. I think only q35 and i440fx are
> > > impacted.
> > > 
> > > > 
> > > > Also what about Daniel's comment in v3:
> > > > https://lore.kernel.org/all/aEak8utPPkHepVfR@redhat.com/
> > > > "For non-x86, historical versioned machine types will need
> > > > likely it set to true, in order to avoid the memory layout
> > > > being changed IIUC."
> > > > 
> > > > Is it actually needed?
> > > 
> > > If those machine types need to set it to true. I think they can set it
> > > after they have this property.
> > nope it does not work like that. In case we really need to take care of
> > this, this must be handled by compats.
> 
> If so. Why don't we still keep the "use-legacy-x86-rom" default to true, and
> only set it to false to those arch which doesn't need it just like my
> original implementation.
> 
> Because I don't really know how other arch's memoery layout was impacted by
> this property set to false. I think keep their original behavior and only
> change it on arm64 is a good idea.
> 
> How do you think about it?

No, the default value of the property shoudl reflect the long
term desired behaviour - in this case 'use-legacy-x86-rom = false'.

We must then reverse this default to 'true' for ALL historical versioned
machine types on ALL architectures, where this device is built, or any
specific machines where we want to keep the historical behaviour going
forward.


With regards,
Daniel
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Re: [PATCH v4 2/2] hw/i386: Add the ramfb romfile compatatibility
Posted by Shaoqin Huang 4 months, 3 weeks ago 
Hi Daniel,

On 6/27/25 3:15 PM, Daniel P. Berrangé wrote:
> On Fri, Jun 27, 2025 at 01:37:55PM +0800, Shaoqin Huang wrote:
>> Hi Eric,
>>
>> On 6/26/25 4:01 PM, Eric Auger wrote:
>>>
>>>
>>> On 6/26/25 4:05 AM, Shaoqin Huang wrote:
>>>> Hi Eric,
>>>>
>>>> On 6/23/25 5:20 PM, Eric Auger wrote:
>>>>>
>>>>>
>>>>> On 6/17/25 5:05 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.
>>>>> s/compatatibility/compatibility in the title
>>>>
>>>> Ok. Will fix it.
>>>>
>>>>>>
>>>>>> Signed-off-by: Shaoqin Huang <shahuang@redhat.com>
>>>>>> ---
>>>>>>     hw/display/ramfb-standalone.c | 2 +-
>>>>>>     hw/i386/pc_q35.c              | 3 +++
>>>>>>     hw/vfio/pci.c                 | 2 +-
>>>>>>     3 files changed, 5 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/hw/display/ramfb-standalone.c b/hw/display/ramfb-
>>>>>> standalone.c
>>>>>> index af1175bf96..ddbf42f181 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, void *data)
>>>>>> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
>>>>>> index fd96d0345c..f6d89578d0 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" },
>>>>> this will only keep the legacy behavior along with q35 machine type but
>>>>> not on other machines being used for x86. what about pc-i440fx? Doesn't
>>>>> it apply to it as well? Are there other machine types also impacted.
>>>>
>>>> Ok I will also add it with pc-i440fx. I think only q35 and i440fx are
>>>> impacted.
>>>>
>>>>>
>>>>> Also what about Daniel's comment in v3:
>>>>> https://lore.kernel.org/all/aEak8utPPkHepVfR@redhat.com/
>>>>> "For non-x86, historical versioned machine types will need
>>>>> likely it set to true, in order to avoid the memory layout
>>>>> being changed IIUC."
>>>>>
>>>>> Is it actually needed?
>>>>
>>>> If those machine types need to set it to true. I think they can set it
>>>> after they have this property.
>>> nope it does not work like that. In case we really need to take care of
>>> this, this must be handled by compats.
>>
>> If so. Why don't we still keep the "use-legacy-x86-rom" default to true, and
>> only set it to false to those arch which doesn't need it just like my
>> original implementation.
>>
>> Because I don't really know how other arch's memoery layout was impacted by
>> this property set to false. I think keep their original behavior and only
>> change it on arm64 is a good idea.
>>
>> How do you think about it?
> 
> No, the default value of the property shoudl reflect the long
> term desired behaviour - in this case 'use-legacy-x86-rom = false'.

Ok I understand your thoughts.

> 
> We must then reverse this default to 'true' for ALL historical versioned
> machine types on ALL architectures, where this device is built, or any
> specific machines where we want to keep the historical behaviour going
> forward.

But how do we implement that?

Maybe set the 'use-legacy-x86-rom = true' in hw_compat_9_2 ?

I'm not sure about that, could you give some hints about how to reverse 
the default to 'true' for ALL historical versioned machine types?

Thanks a lot.

> 
> 
> With regards,
> Daniel

-- 
Shaoqin

Patchew 2.1-devel-b67e4c2

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