Re: [PATCH v3 2/2] hw/arm: Add the romfile compatatibility

[Shaoqin Huang <shahuang@redhat.com>]

On 6/9/25 5:10 PM, Daniel P. Berrangé wrote:
> On Mon, Jun 09, 2025 at 09:48:36AM +0100, Peter Maydell wrote:
>> On Mon, 9 Jun 2025 at 08:34, Shaoqin Huang <shahuang@redhat.com> wrote:
>>>
>>> On arm64, it doesn't use the vgabios-ramfb.bin, so set the property
>>> "use-legacy-x86-rom" to false, thus the ramfb won't load the
>>> vgabios-ramfb.bin.
>>>
>>> This can mitigate the problem that on release version the qemu can't
>>> find the vgabios-ramfb.bin if it use the ramfb.
>>>
>>> Signed-off-by: Shaoqin Huang <shahuang@redhat.com>
>>> ---
>>>   hw/arm/virt.c | 3 +++
>>>   1 file changed, 3 insertions(+)
>>>
>>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>>> index a96452f17a..5f94f7a2ca 100644
>>> --- a/hw/arm/virt.c
>>> +++ b/hw/arm/virt.c
>>> @@ -38,6 +38,7 @@
>>>   #include "hw/arm/primecell.h"
>>>   #include "hw/arm/virt.h"
>>>   #include "hw/block/flash.h"
>>> +#include "hw/vfio/pci.h"
>>>   #include "hw/vfio/vfio-calxeda-xgmac.h"
>>>   #include "hw/vfio/vfio-amd-xgbe.h"
>>>   #include "hw/display/ramfb.h"
>>> @@ -90,6 +91,8 @@
>>>
>>>   static GlobalProperty arm_virt_compat[] = {
>>>       { TYPE_VIRTIO_IOMMU_PCI, "aw-bits", "48" },
>>> +    { TYPE_RAMFB_DEVICE, "use-legacy-x86-rom", "false" },
>>> +    { TYPE_VFIO_PCI, "use-legacy-x86-rom", "false" },
>>
>> I think we should find a way to make this default to "false"
>> and only be set "true" for x86. Otherwise every single non-x86
>> board that ever adds support for ramfb and virtio will have
>> to add these two lines, which is a source of future bugs.
>> (Whereas if you forget to mark a new x86 board as needing
>> the legacy rom you'll find out about it pretty quickly.)
> 
> Yes, going forward we this to default to true only on x86.
> 
> For non-x86, historical versioned machine types will need
> likely it set to true, in order to avoid the memory layout
> being changed IIUC.

Ok, I will set this to be true by default only on x86.

Thanks,
Shaoqin

> 
> 
> With regards,
> Daniel

-- 
Shaoqin