[PATCH] PCI: vgaarb: Include 0x0380 devices in default selection

[PATCH] PCI: vgaarb: Include 0x0380 devices in default selection

[Aaron Ma]

Some firmware boot GPUs report class 0x0380 (PCI_CLASS_DISPLAY_OTHER)
instead of PCI_CLASS_DISPLAY_VGA. vgaarb only registers pci_is_vga()
devices, so those GPUs are not considered by vga_is_firmware_default().

On these systems the AMD GPU matches the EFI framebuffer but is
excluded from vgaarb because it is class 0x0380, while the NVIDIA GPU
does not match the EFI framebuffer but becomes vga_default_device()
through the vgaarb's enabled-device fallback.

Register legacy VGA and 0x0380 devices in vgaarb, and expose boot_vga
for the same set of devices, so the firmware default device can be
selected correctly.

Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
---
 drivers/pci/pci-sysfs.c |  3 ++-
 drivers/pci/vgaarb.c    | 10 +++++-----
 include/linux/pci.h     | 14 ++++++++++++++
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index d37860841260c..843d83ec9550a 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1717,7 +1717,8 @@ static umode_t pci_dev_attrs_are_visible(struct kobject *kobj,
 	struct device *dev = kobj_to_dev(kobj);
 	struct pci_dev *pdev = to_pci_dev(dev);
 
-	if (a == &dev_attr_boot_vga.attr && pci_is_vga(pdev))
+	if (a == &dev_attr_boot_vga.attr &&
+	    pci_is_vga_or_other_display(pdev))
 		return a->mode;
 
 	if (a == &dev_attr_serial_number.attr && pci_get_dsn(pdev))
diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
index c360eee11dd9e..0e0878189e3d8 100644
--- a/drivers/pci/vgaarb.c
+++ b/drivers/pci/vgaarb.c
@@ -796,7 +796,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
 	}
 
 	if (vga_is_boot_device(vgadev)) {
-		vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
+		vgaarb_info(&pdev->dev, "setting as boot display device%s\n",
 			    vga_default_device() ?
 			    " (overriding previous)" : "");
 		vga_set_default_device(pdev);
@@ -1483,8 +1483,8 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
 
 	vgaarb_dbg(dev, "%s\n", __func__);
 
-	/* Only deal with VGA class devices */
-	if (!pci_is_vga(pdev))
+	/* Only deal with legacy VGA and other display controller devices */
+	if (!pci_is_vga_or_other_display(pdev))
 		return 0;
 
 	/*
@@ -1530,12 +1530,12 @@ static int __init vga_arb_device_init(void)
 
 	bus_register_notifier(&pci_bus_type, &pci_notifier);
 
-	/* Add all VGA class PCI devices by default */
+	/* Add legacy VGA and other display controller PCI devices by default */
 	pdev = NULL;
 	while ((pdev =
 		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
 			       PCI_ANY_ID, pdev)) != NULL) {
-		if (pci_is_vga(pdev))
+		if (pci_is_vga_or_other_display(pdev))
 			vga_arbiter_add_pci_device(pdev);
 	}
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 2c4454583c115..195ec1bdac863 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -792,6 +792,20 @@ static inline bool pci_is_vga(struct pci_dev *pdev)
 	return false;
 }
 
+/**
+ * pci_is_vga_or_other_display - check if the PCI device is VGA or 0x0380
+ * @pdev: PCI device
+ *
+ * Return true for legacy VGA-compatible devices and for "other display
+ * controller" devices.  Some firmware-selected boot display devices expose
+ * class 0x0380 instead of PCI_CLASS_DISPLAY_VGA.
+ */
+static inline bool pci_is_vga_or_other_display(struct pci_dev *pdev)
+{
+	return pci_is_vga(pdev) ||
+		(pdev->class >> 8) == PCI_CLASS_DISPLAY_OTHER;
+}
+
 /**
  * pci_is_display - check if the PCI device is a display controller
  * @pdev: PCI device
-- 
2.43.0

Re: [PATCH] PCI: vgaarb: Include 0x0380 devices in default selection

[Mario Limonciello]

On 6/18/26 01:18, Aaron Ma wrote:
> Some firmware boot GPUs report class 0x0380 (PCI_CLASS_DISPLAY_OTHER)
> instead of PCI_CLASS_DISPLAY_VGA. vgaarb only registers pci_is_vga()
> devices, so those GPUs are not considered by vga_is_firmware_default().
> 
> On these systems the AMD GPU matches the EFI framebuffer but is
> excluded from vgaarb because it is class 0x0380, while the NVIDIA GPU
> does not match the EFI framebuffer but becomes vga_default_device()
> through the vgaarb's enabled-device fallback.
> 
> Register legacy VGA and 0x0380 devices in vgaarb, and expose boot_vga
> for the same set of devices, so the firmware default device can be
> selected correctly.
> 
> Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
> ---
>   drivers/pci/pci-sysfs.c |  3 ++-
>   drivers/pci/vgaarb.c    | 10 +++++-----
>   include/linux/pci.h     | 14 ++++++++++++++
>   3 files changed, 21 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index d37860841260c..843d83ec9550a 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -1717,7 +1717,8 @@ static umode_t pci_dev_attrs_are_visible(struct kobject *kobj,
>   	struct device *dev = kobj_to_dev(kobj);
>   	struct pci_dev *pdev = to_pci_dev(dev);
>   
> -	if (a == &dev_attr_boot_vga.attr && pci_is_vga(pdev))
> +	if (a == &dev_attr_boot_vga.attr &&
> +	    pci_is_vga_or_other_display(pdev))
>   		return a->mode;
 >   >   	if (a == &dev_attr_serial_number.attr && pci_get_dsn(pdev))
> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
> index c360eee11dd9e..0e0878189e3d8 100644
> --- a/drivers/pci/vgaarb.c
> +++ b/drivers/pci/vgaarb.c
> @@ -796,7 +796,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
>   	}
>   
>   	if (vga_is_boot_device(vgadev)) {
> -		vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
> +		vgaarb_info(&pdev->dev, "setting as boot display device%s\n",
>   			    vga_default_device() ?
>   			    " (overriding previous)" : "");
>   		vga_set_default_device(pdev);
> @@ -1483,8 +1483,8 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
>   
>   	vgaarb_dbg(dev, "%s\n", __func__);
>   
> -	/* Only deal with VGA class devices */
> -	if (!pci_is_vga(pdev))
> +	/* Only deal with legacy VGA and other display controller devices */
> +	if (!pci_is_vga_or_other_display(pdev)) >   		return 0;
>   
>   	/*
> @@ -1530,12 +1530,12 @@ static int __init vga_arb_device_init(void)
>   
>   	bus_register_notifier(&pci_bus_type, &pci_notifier);
>   
> -	/* Add all VGA class PCI devices by default */
> +	/* Add legacy VGA and other display controller PCI devices by default */
>   	pdev = NULL;
>   	while ((pdev =
>   		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
>   			       PCI_ANY_ID, pdev)) != NULL) {
> -		if (pci_is_vga(pdev))
> +		if (pci_is_vga_or_other_display(pdev))
>   			vga_arbiter_add_pci_device(pdev);
>   	}
>   
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 2c4454583c115..195ec1bdac863 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -792,6 +792,20 @@ static inline bool pci_is_vga(struct pci_dev *pdev)
>   	return false;
>   }
>   
> +/**
> + * pci_is_vga_or_other_display - check if the PCI device is VGA or 0x0380
> + * @pdev: PCI device
> + *
> + * Return true for legacy VGA-compatible devices and for "other display
> + * controller" devices.  Some firmware-selected boot display devices expose
> + * class 0x0380 instead of PCI_CLASS_DISPLAY_VGA.
> + */
> +static inline bool pci_is_vga_or_other_display(struct pci_dev *pdev)
> +{
> +	return pci_is_vga(pdev) ||
> +		(pdev->class >> 8) == PCI_CLASS_DISPLAY_OTHER;
> +}
> +
>   /**
>    * pci_is_display - check if the PCI device is a display controller
>    * @pdev: PCI device


This patch doesn't seem correct to me.  It's overloading the purpose of 
boot_vga to cover non VGA devices.  We should be using boot_display.

Trying to hypothesize what's going on here - I guess you're seeing 
boot_display set for more than one device due to enumeration order.

Can you see if this helps instead?

╰─❯ git diff
diff --git a/arch/x86/video/video-common.c b/arch/x86/video/video-common.c
index 152789f00fcda..9440eb3a7b15d 100644
--- a/arch/x86/video/video-common.c
+++ b/arch/x86/video/video-common.c
@@ -43,9 +43,6 @@ bool video_is_primary_device(struct device *dev)
         if (!pci_is_display(pdev))
                 return false;

-       if (pdev == vga_default_device())
-               return true;
-
  #ifdef CONFIG_SCREEN_INFO
         numres = screen_info_resources(si, res, ARRAY_SIZE(res));
         for (i = 0; i < numres; ++i) {

Re: [PATCH] PCI: vgaarb: Include 0x0380 devices in default selection

[Aaron Ma]

On Mon, Jun 22, 2026 at 1:15 AM Mario Limonciello
<mario.limonciello@amd.com> wrote:
>
>
>
> On 6/18/26 01:18, Aaron Ma wrote:
> > Some firmware boot GPUs report class 0x0380 (PCI_CLASS_DISPLAY_OTHER)
> > instead of PCI_CLASS_DISPLAY_VGA. vgaarb only registers pci_is_vga()
> > devices, so those GPUs are not considered by vga_is_firmware_default().
> >
> > On these systems the AMD GPU matches the EFI framebuffer but is
> > excluded from vgaarb because it is class 0x0380, while the NVIDIA GPU
> > does not match the EFI framebuffer but becomes vga_default_device()
> > through the vgaarb's enabled-device fallback.
> >
> > Register legacy VGA and 0x0380 devices in vgaarb, and expose boot_vga
> > for the same set of devices, so the firmware default device can be
> > selected correctly.
> >
> > Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
> > ---
> >   drivers/pci/pci-sysfs.c |  3 ++-
> >   drivers/pci/vgaarb.c    | 10 +++++-----
> >   include/linux/pci.h     | 14 ++++++++++++++
> >   3 files changed, 21 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> > index d37860841260c..843d83ec9550a 100644
> > --- a/drivers/pci/pci-sysfs.c
> > +++ b/drivers/pci/pci-sysfs.c
> > @@ -1717,7 +1717,8 @@ static umode_t pci_dev_attrs_are_visible(struct kobject *kobj,
> >       struct device *dev = kobj_to_dev(kobj);
> >       struct pci_dev *pdev = to_pci_dev(dev);
> >
> > -     if (a == &dev_attr_boot_vga.attr && pci_is_vga(pdev))
> > +     if (a == &dev_attr_boot_vga.attr &&
> > +         pci_is_vga_or_other_display(pdev))
> >               return a->mode;
>  >   >          if (a == &dev_attr_serial_number.attr && pci_get_dsn(pdev))
> > diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
> > index c360eee11dd9e..0e0878189e3d8 100644
> > --- a/drivers/pci/vgaarb.c
> > +++ b/drivers/pci/vgaarb.c
> > @@ -796,7 +796,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
> >       }
> >
> >       if (vga_is_boot_device(vgadev)) {
> > -             vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
> > +             vgaarb_info(&pdev->dev, "setting as boot display device%s\n",
> >                           vga_default_device() ?
> >                           " (overriding previous)" : "");
> >               vga_set_default_device(pdev);
> > @@ -1483,8 +1483,8 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
> >
> >       vgaarb_dbg(dev, "%s\n", __func__);
> >
> > -     /* Only deal with VGA class devices */
> > -     if (!pci_is_vga(pdev))
> > +     /* Only deal with legacy VGA and other display controller devices */
> > +     if (!pci_is_vga_or_other_display(pdev)) >               return 0;
> >
> >       /*
> > @@ -1530,12 +1530,12 @@ static int __init vga_arb_device_init(void)
> >
> >       bus_register_notifier(&pci_bus_type, &pci_notifier);
> >
> > -     /* Add all VGA class PCI devices by default */
> > +     /* Add legacy VGA and other display controller PCI devices by default */
> >       pdev = NULL;
> >       while ((pdev =
> >               pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> >                              PCI_ANY_ID, pdev)) != NULL) {
> > -             if (pci_is_vga(pdev))
> > +             if (pci_is_vga_or_other_display(pdev))
> >                       vga_arbiter_add_pci_device(pdev);
> >       }
> >
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index 2c4454583c115..195ec1bdac863 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -792,6 +792,20 @@ static inline bool pci_is_vga(struct pci_dev *pdev)
> >       return false;
> >   }
> >
> > +/**
> > + * pci_is_vga_or_other_display - check if the PCI device is VGA or 0x0380
> > + * @pdev: PCI device
> > + *
> > + * Return true for legacy VGA-compatible devices and for "other display
> > + * controller" devices.  Some firmware-selected boot display devices expose
> > + * class 0x0380 instead of PCI_CLASS_DISPLAY_VGA.
> > + */
> > +static inline bool pci_is_vga_or_other_display(struct pci_dev *pdev)
> > +{
> > +     return pci_is_vga(pdev) ||
> > +             (pdev->class >> 8) == PCI_CLASS_DISPLAY_OTHER;
> > +}
> > +
> >   /**
> >    * pci_is_display - check if the PCI device is a display controller
> >    * @pdev: PCI device
>
>
> This patch doesn't seem correct to me.  It's overloading the purpose of
> boot_vga to cover non VGA devices.  We should be using boot_display.
>
> Trying to hypothesize what's going on here - I guess you're seeing
> boot_display set for more than one device due to enumeration order.
>
> Can you see if this helps instead?
>
> ╰─❯ git diff
> diff --git a/arch/x86/video/video-common.c b/arch/x86/video/video-common.c
> index 152789f00fcda..9440eb3a7b15d 100644
> --- a/arch/x86/video/video-common.c
> +++ b/arch/x86/video/video-common.c
> @@ -43,9 +43,6 @@ bool video_is_primary_device(struct device *dev)
>          if (!pci_is_display(pdev))
>                  return false;
>
> -       if (pdev == vga_default_device())
> -               return true;
> -
>   #ifdef CONFIG_SCREEN_INFO
>          numres = screen_info_resources(si, res, ARRAY_SIZE(res));
>          for (i = 0; i < numres; ++i) {

Hi Mario,

I tested your change. boot_display becomes correct, but the issue is not fixed.

The kernel state becomes:

  AMD:    boot_display=1, boot_vga absent
  NVIDIA: boot_display absent, boot_vga=1

Current Xorg checks boot_display || boot_vga, so both GPUs still match.
The selected primary GPU still depends on Xorg's DRM device enumeration order.

So boot_vga is still wrong, and that still matters. The kernel should not
expose boot_vga=1 for NVIDIA when the firmware framebuffer is on AMD.

My patch makes boot_vga and boot_display agree on the AMD boot display.

Thanks,
Aaron

Re: [PATCH] PCI: vgaarb: Include 0x0380 devices in default selection

[Mario Limonciello]

On 6/21/26 20:50, Aaron Ma wrote:
> On Mon, Jun 22, 2026 at 1:15 AM Mario Limonciello
> <mario.limonciello@amd.com> wrote:
>>
>>
>>
>> On 6/18/26 01:18, Aaron Ma wrote:
>>> Some firmware boot GPUs report class 0x0380 (PCI_CLASS_DISPLAY_OTHER)
>>> instead of PCI_CLASS_DISPLAY_VGA. vgaarb only registers pci_is_vga()
>>> devices, so those GPUs are not considered by vga_is_firmware_default().
>>>
>>> On these systems the AMD GPU matches the EFI framebuffer but is
>>> excluded from vgaarb because it is class 0x0380, while the NVIDIA GPU
>>> does not match the EFI framebuffer but becomes vga_default_device()
>>> through the vgaarb's enabled-device fallback.
>>>
>>> Register legacy VGA and 0x0380 devices in vgaarb, and expose boot_vga
>>> for the same set of devices, so the firmware default device can be
>>> selected correctly.
>>>
>>> Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
>>> ---
>>>    drivers/pci/pci-sysfs.c |  3 ++-
>>>    drivers/pci/vgaarb.c    | 10 +++++-----
>>>    include/linux/pci.h     | 14 ++++++++++++++
>>>    3 files changed, 21 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
>>> index d37860841260c..843d83ec9550a 100644
>>> --- a/drivers/pci/pci-sysfs.c
>>> +++ b/drivers/pci/pci-sysfs.c
>>> @@ -1717,7 +1717,8 @@ static umode_t pci_dev_attrs_are_visible(struct kobject *kobj,
>>>        struct device *dev = kobj_to_dev(kobj);
>>>        struct pci_dev *pdev = to_pci_dev(dev);
>>>
>>> -     if (a == &dev_attr_boot_vga.attr && pci_is_vga(pdev))
>>> +     if (a == &dev_attr_boot_vga.attr &&
>>> +         pci_is_vga_or_other_display(pdev))
>>>                return a->mode;
>>   >   >          if (a == &dev_attr_serial_number.attr && pci_get_dsn(pdev))
>>> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
>>> index c360eee11dd9e..0e0878189e3d8 100644
>>> --- a/drivers/pci/vgaarb.c
>>> +++ b/drivers/pci/vgaarb.c
>>> @@ -796,7 +796,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
>>>        }
>>>
>>>        if (vga_is_boot_device(vgadev)) {
>>> -             vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
>>> +             vgaarb_info(&pdev->dev, "setting as boot display device%s\n",
>>>                            vga_default_device() ?
>>>                            " (overriding previous)" : "");
>>>                vga_set_default_device(pdev);
>>> @@ -1483,8 +1483,8 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
>>>
>>>        vgaarb_dbg(dev, "%s\n", __func__);
>>>
>>> -     /* Only deal with VGA class devices */
>>> -     if (!pci_is_vga(pdev))
>>> +     /* Only deal with legacy VGA and other display controller devices */
>>> +     if (!pci_is_vga_or_other_display(pdev)) >               return 0;
>>>
>>>        /*
>>> @@ -1530,12 +1530,12 @@ static int __init vga_arb_device_init(void)
>>>
>>>        bus_register_notifier(&pci_bus_type, &pci_notifier);
>>>
>>> -     /* Add all VGA class PCI devices by default */
>>> +     /* Add legacy VGA and other display controller PCI devices by default */
>>>        pdev = NULL;
>>>        while ((pdev =
>>>                pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
>>>                               PCI_ANY_ID, pdev)) != NULL) {
>>> -             if (pci_is_vga(pdev))
>>> +             if (pci_is_vga_or_other_display(pdev))
>>>                        vga_arbiter_add_pci_device(pdev);
>>>        }
>>>
>>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>>> index 2c4454583c115..195ec1bdac863 100644
>>> --- a/include/linux/pci.h
>>> +++ b/include/linux/pci.h
>>> @@ -792,6 +792,20 @@ static inline bool pci_is_vga(struct pci_dev *pdev)
>>>        return false;
>>>    }
>>>
>>> +/**
>>> + * pci_is_vga_or_other_display - check if the PCI device is VGA or 0x0380
>>> + * @pdev: PCI device
>>> + *
>>> + * Return true for legacy VGA-compatible devices and for "other display
>>> + * controller" devices.  Some firmware-selected boot display devices expose
>>> + * class 0x0380 instead of PCI_CLASS_DISPLAY_VGA.
>>> + */
>>> +static inline bool pci_is_vga_or_other_display(struct pci_dev *pdev)
>>> +{
>>> +     return pci_is_vga(pdev) ||
>>> +             (pdev->class >> 8) == PCI_CLASS_DISPLAY_OTHER;
>>> +}
>>> +
>>>    /**
>>>     * pci_is_display - check if the PCI device is a display controller
>>>     * @pdev: PCI device
>>
>>
>> This patch doesn't seem correct to me.  It's overloading the purpose of
>> boot_vga to cover non VGA devices.  We should be using boot_display.
>>
>> Trying to hypothesize what's going on here - I guess you're seeing
>> boot_display set for more than one device due to enumeration order.
>>
>> Can you see if this helps instead?
>>
>> ╰─❯ git diff
>> diff --git a/arch/x86/video/video-common.c b/arch/x86/video/video-common.c
>> index 152789f00fcda..9440eb3a7b15d 100644
>> --- a/arch/x86/video/video-common.c
>> +++ b/arch/x86/video/video-common.c
>> @@ -43,9 +43,6 @@ bool video_is_primary_device(struct device *dev)
>>           if (!pci_is_display(pdev))
>>                   return false;
>>
>> -       if (pdev == vga_default_device())
>> -               return true;
>> -
>>    #ifdef CONFIG_SCREEN_INFO
>>           numres = screen_info_resources(si, res, ARRAY_SIZE(res));
>>           for (i = 0; i < numres; ++i) {
> 
> Hi Mario,
> 
> I tested your change. boot_display becomes correct, but the issue is not fixed.
> 
> The kernel state becomes:
> 
>    AMD:    boot_display=1, boot_vga absent
>    NVIDIA: boot_display absent, boot_vga=1
> 
> Current Xorg checks boot_display || boot_vga, so both GPUs still match.
> The selected primary GPU still depends on Xorg's DRM device enumeration order.
> 
> So boot_vga is still wrong, and that still matters. The kernel should not
> expose boot_vga=1 for NVIDIA when the firmware framebuffer is on AMD.
> 
> My patch makes boot_vga and boot_display agree on the AMD boot display.
> 
> Thanks,
> Aaron

Got it.  I still don't think it's correct to overload boot_vga.  It 
would be better for us to not show boot_vga at all - because it's not 
correct.

Maybe we should drop the fallback code in VGA arbiter that is setting 
NVIDIA as boot_vga at all.

Could you look at doing that?

Re: [PATCH] PCI: vgaarb: Include 0x0380 devices in default selection

[Aaron Ma]

On Mon, Jun 22, 2026 at 12:00 PM Mario Limonciello
<mario.limonciello@amd.com> wrote:
>
>
>
> On 6/21/26 20:50, Aaron Ma wrote:
> > On Mon, Jun 22, 2026 at 1:15 AM Mario Limonciello
> > <mario.limonciello@amd.com> wrote:
> >>
> >>
> >>
> >> On 6/18/26 01:18, Aaron Ma wrote:
> >>> Some firmware boot GPUs report class 0x0380 (PCI_CLASS_DISPLAY_OTHER)
> >>> instead of PCI_CLASS_DISPLAY_VGA. vgaarb only registers pci_is_vga()
> >>> devices, so those GPUs are not considered by vga_is_firmware_default().
> >>>
> >>> On these systems the AMD GPU matches the EFI framebuffer but is
> >>> excluded from vgaarb because it is class 0x0380, while the NVIDIA GPU
> >>> does not match the EFI framebuffer but becomes vga_default_device()
> >>> through the vgaarb's enabled-device fallback.
> >>>
> >>> Register legacy VGA and 0x0380 devices in vgaarb, and expose boot_vga
> >>> for the same set of devices, so the firmware default device can be
> >>> selected correctly.
> >>>
> >>> Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
> >>> ---
> >>>    drivers/pci/pci-sysfs.c |  3 ++-
> >>>    drivers/pci/vgaarb.c    | 10 +++++-----
> >>>    include/linux/pci.h     | 14 ++++++++++++++
> >>>    3 files changed, 21 insertions(+), 6 deletions(-)
> >>>
> >>> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> >>> index d37860841260c..843d83ec9550a 100644
> >>> --- a/drivers/pci/pci-sysfs.c
> >>> +++ b/drivers/pci/pci-sysfs.c
> >>> @@ -1717,7 +1717,8 @@ static umode_t pci_dev_attrs_are_visible(struct kobject *kobj,
> >>>        struct device *dev = kobj_to_dev(kobj);
> >>>        struct pci_dev *pdev = to_pci_dev(dev);
> >>>
> >>> -     if (a == &dev_attr_boot_vga.attr && pci_is_vga(pdev))
> >>> +     if (a == &dev_attr_boot_vga.attr &&
> >>> +         pci_is_vga_or_other_display(pdev))
> >>>                return a->mode;
> >>   >   >          if (a == &dev_attr_serial_number.attr && pci_get_dsn(pdev))
> >>> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
> >>> index c360eee11dd9e..0e0878189e3d8 100644
> >>> --- a/drivers/pci/vgaarb.c
> >>> +++ b/drivers/pci/vgaarb.c
> >>> @@ -796,7 +796,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
> >>>        }
> >>>
> >>>        if (vga_is_boot_device(vgadev)) {
> >>> -             vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
> >>> +             vgaarb_info(&pdev->dev, "setting as boot display device%s\n",
> >>>                            vga_default_device() ?
> >>>                            " (overriding previous)" : "");
> >>>                vga_set_default_device(pdev);
> >>> @@ -1483,8 +1483,8 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
> >>>
> >>>        vgaarb_dbg(dev, "%s\n", __func__);
> >>>
> >>> -     /* Only deal with VGA class devices */
> >>> -     if (!pci_is_vga(pdev))
> >>> +     /* Only deal with legacy VGA and other display controller devices */
> >>> +     if (!pci_is_vga_or_other_display(pdev)) >               return 0;
> >>>
> >>>        /*
> >>> @@ -1530,12 +1530,12 @@ static int __init vga_arb_device_init(void)
> >>>
> >>>        bus_register_notifier(&pci_bus_type, &pci_notifier);
> >>>
> >>> -     /* Add all VGA class PCI devices by default */
> >>> +     /* Add legacy VGA and other display controller PCI devices by default */
> >>>        pdev = NULL;
> >>>        while ((pdev =
> >>>                pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> >>>                               PCI_ANY_ID, pdev)) != NULL) {
> >>> -             if (pci_is_vga(pdev))
> >>> +             if (pci_is_vga_or_other_display(pdev))
> >>>                        vga_arbiter_add_pci_device(pdev);
> >>>        }
> >>>
> >>> diff --git a/include/linux/pci.h b/include/linux/pci.h
> >>> index 2c4454583c115..195ec1bdac863 100644
> >>> --- a/include/linux/pci.h
> >>> +++ b/include/linux/pci.h
> >>> @@ -792,6 +792,20 @@ static inline bool pci_is_vga(struct pci_dev *pdev)
> >>>        return false;
> >>>    }
> >>>
> >>> +/**
> >>> + * pci_is_vga_or_other_display - check if the PCI device is VGA or 0x0380
> >>> + * @pdev: PCI device
> >>> + *
> >>> + * Return true for legacy VGA-compatible devices and for "other display
> >>> + * controller" devices.  Some firmware-selected boot display devices expose
> >>> + * class 0x0380 instead of PCI_CLASS_DISPLAY_VGA.
> >>> + */
> >>> +static inline bool pci_is_vga_or_other_display(struct pci_dev *pdev)
> >>> +{
> >>> +     return pci_is_vga(pdev) ||
> >>> +             (pdev->class >> 8) == PCI_CLASS_DISPLAY_OTHER;
> >>> +}
> >>> +
> >>>    /**
> >>>     * pci_is_display - check if the PCI device is a display controller
> >>>     * @pdev: PCI device
> >>
> >>
> >> This patch doesn't seem correct to me.  It's overloading the purpose of
> >> boot_vga to cover non VGA devices.  We should be using boot_display.
> >>
> >> Trying to hypothesize what's going on here - I guess you're seeing
> >> boot_display set for more than one device due to enumeration order.
> >>
> >> Can you see if this helps instead?
> >>
> >> ╰─❯ git diff
> >> diff --git a/arch/x86/video/video-common.c b/arch/x86/video/video-common.c
> >> index 152789f00fcda..9440eb3a7b15d 100644
> >> --- a/arch/x86/video/video-common.c
> >> +++ b/arch/x86/video/video-common.c
> >> @@ -43,9 +43,6 @@ bool video_is_primary_device(struct device *dev)
> >>           if (!pci_is_display(pdev))
> >>                   return false;
> >>
> >> -       if (pdev == vga_default_device())
> >> -               return true;
> >> -
> >>    #ifdef CONFIG_SCREEN_INFO
> >>           numres = screen_info_resources(si, res, ARRAY_SIZE(res));
> >>           for (i = 0; i < numres; ++i) {
> >
> > Hi Mario,
> >
> > I tested your change. boot_display becomes correct, but the issue is not fixed.
> >
> > The kernel state becomes:
> >
> >    AMD:    boot_display=1, boot_vga absent
> >    NVIDIA: boot_display absent, boot_vga=1
> >
> > Current Xorg checks boot_display || boot_vga, so both GPUs still match.
> > The selected primary GPU still depends on Xorg's DRM device enumeration order.
> >
> > So boot_vga is still wrong, and that still matters. The kernel should not
> > expose boot_vga=1 for NVIDIA when the firmware framebuffer is on AMD.
> >
> > My patch makes boot_vga and boot_display agree on the AMD boot display.
> >
> > Thanks,
> > Aaron
>
> Got it.  I still don't think it's correct to overload boot_vga.  It
> would be better for us to not show boot_vga at all - because it's not
> correct.
>
> Maybe we should drop the fallback code in VGA arbiter that is setting
> NVIDIA as boot_vga at all.
>
> Could you look at doing that?
>

Hi Mario,

I looked at dropping the fallback. I don't think we should remove it globally;
old systems may still need vga_default_device() when no firmware framebuffer
owner can be identified.

For v2 I will keep the fallback, but avoid the wrong result on this system. The
0x0380 firmware display can become the default/boot_vga device, while legacy
VGA decoding and ownership stay limited to pci_is_vga() devices.

So this keeps compatibility, but avoids reporting NVIDIA as boot_vga when the
firmware framebuffer is on AMD.

Thanks,
Aaron

Re: [PATCH] PCI: vgaarb: Include 0x0380 devices in default selection

[Mario Limonciello]

On 6/21/26 23:12, Aaron Ma wrote:
> On Mon, Jun 22, 2026 at 12:00 PM Mario Limonciello
> <mario.limonciello@amd.com> wrote:
>>
>>
>>
>> On 6/21/26 20:50, Aaron Ma wrote:
>>> On Mon, Jun 22, 2026 at 1:15 AM Mario Limonciello
>>> <mario.limonciello@amd.com> wrote:
>>>>
>>>>
>>>>
>>>> On 6/18/26 01:18, Aaron Ma wrote:
>>>>> Some firmware boot GPUs report class 0x0380 (PCI_CLASS_DISPLAY_OTHER)
>>>>> instead of PCI_CLASS_DISPLAY_VGA. vgaarb only registers pci_is_vga()
>>>>> devices, so those GPUs are not considered by vga_is_firmware_default().
>>>>>
>>>>> On these systems the AMD GPU matches the EFI framebuffer but is
>>>>> excluded from vgaarb because it is class 0x0380, while the NVIDIA GPU
>>>>> does not match the EFI framebuffer but becomes vga_default_device()
>>>>> through the vgaarb's enabled-device fallback.
>>>>>
>>>>> Register legacy VGA and 0x0380 devices in vgaarb, and expose boot_vga
>>>>> for the same set of devices, so the firmware default device can be
>>>>> selected correctly.
>>>>>
>>>>> Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
>>>>> ---
>>>>>     drivers/pci/pci-sysfs.c |  3 ++-
>>>>>     drivers/pci/vgaarb.c    | 10 +++++-----
>>>>>     include/linux/pci.h     | 14 ++++++++++++++
>>>>>     3 files changed, 21 insertions(+), 6 deletions(-)
>>>>>
>>>>> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
>>>>> index d37860841260c..843d83ec9550a 100644
>>>>> --- a/drivers/pci/pci-sysfs.c
>>>>> +++ b/drivers/pci/pci-sysfs.c
>>>>> @@ -1717,7 +1717,8 @@ static umode_t pci_dev_attrs_are_visible(struct kobject *kobj,
>>>>>         struct device *dev = kobj_to_dev(kobj);
>>>>>         struct pci_dev *pdev = to_pci_dev(dev);
>>>>>
>>>>> -     if (a == &dev_attr_boot_vga.attr && pci_is_vga(pdev))
>>>>> +     if (a == &dev_attr_boot_vga.attr &&
>>>>> +         pci_is_vga_or_other_display(pdev))
>>>>>                 return a->mode;
>>>>    >   >          if (a == &dev_attr_serial_number.attr && pci_get_dsn(pdev))
>>>>> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
>>>>> index c360eee11dd9e..0e0878189e3d8 100644
>>>>> --- a/drivers/pci/vgaarb.c
>>>>> +++ b/drivers/pci/vgaarb.c
>>>>> @@ -796,7 +796,7 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
>>>>>         }
>>>>>
>>>>>         if (vga_is_boot_device(vgadev)) {
>>>>> -             vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
>>>>> +             vgaarb_info(&pdev->dev, "setting as boot display device%s\n",
>>>>>                             vga_default_device() ?
>>>>>                             " (overriding previous)" : "");
>>>>>                 vga_set_default_device(pdev);
>>>>> @@ -1483,8 +1483,8 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
>>>>>
>>>>>         vgaarb_dbg(dev, "%s\n", __func__);
>>>>>
>>>>> -     /* Only deal with VGA class devices */
>>>>> -     if (!pci_is_vga(pdev))
>>>>> +     /* Only deal with legacy VGA and other display controller devices */
>>>>> +     if (!pci_is_vga_or_other_display(pdev)) >               return 0;
>>>>>
>>>>>         /*
>>>>> @@ -1530,12 +1530,12 @@ static int __init vga_arb_device_init(void)
>>>>>
>>>>>         bus_register_notifier(&pci_bus_type, &pci_notifier);
>>>>>
>>>>> -     /* Add all VGA class PCI devices by default */
>>>>> +     /* Add legacy VGA and other display controller PCI devices by default */
>>>>>         pdev = NULL;
>>>>>         while ((pdev =
>>>>>                 pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
>>>>>                                PCI_ANY_ID, pdev)) != NULL) {
>>>>> -             if (pci_is_vga(pdev))
>>>>> +             if (pci_is_vga_or_other_display(pdev))
>>>>>                         vga_arbiter_add_pci_device(pdev);
>>>>>         }
>>>>>
>>>>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>>>>> index 2c4454583c115..195ec1bdac863 100644
>>>>> --- a/include/linux/pci.h
>>>>> +++ b/include/linux/pci.h
>>>>> @@ -792,6 +792,20 @@ static inline bool pci_is_vga(struct pci_dev *pdev)
>>>>>         return false;
>>>>>     }
>>>>>
>>>>> +/**
>>>>> + * pci_is_vga_or_other_display - check if the PCI device is VGA or 0x0380
>>>>> + * @pdev: PCI device
>>>>> + *
>>>>> + * Return true for legacy VGA-compatible devices and for "other display
>>>>> + * controller" devices.  Some firmware-selected boot display devices expose
>>>>> + * class 0x0380 instead of PCI_CLASS_DISPLAY_VGA.
>>>>> + */
>>>>> +static inline bool pci_is_vga_or_other_display(struct pci_dev *pdev)
>>>>> +{
>>>>> +     return pci_is_vga(pdev) ||
>>>>> +             (pdev->class >> 8) == PCI_CLASS_DISPLAY_OTHER;
>>>>> +}
>>>>> +
>>>>>     /**
>>>>>      * pci_is_display - check if the PCI device is a display controller
>>>>>      * @pdev: PCI device
>>>>
>>>>
>>>> This patch doesn't seem correct to me.  It's overloading the purpose of
>>>> boot_vga to cover non VGA devices.  We should be using boot_display.
>>>>
>>>> Trying to hypothesize what's going on here - I guess you're seeing
>>>> boot_display set for more than one device due to enumeration order.
>>>>
>>>> Can you see if this helps instead?
>>>>
>>>> ╰─❯ git diff
>>>> diff --git a/arch/x86/video/video-common.c b/arch/x86/video/video-common.c
>>>> index 152789f00fcda..9440eb3a7b15d 100644
>>>> --- a/arch/x86/video/video-common.c
>>>> +++ b/arch/x86/video/video-common.c
>>>> @@ -43,9 +43,6 @@ bool video_is_primary_device(struct device *dev)
>>>>            if (!pci_is_display(pdev))
>>>>                    return false;
>>>>
>>>> -       if (pdev == vga_default_device())
>>>> -               return true;
>>>> -
>>>>     #ifdef CONFIG_SCREEN_INFO
>>>>            numres = screen_info_resources(si, res, ARRAY_SIZE(res));
>>>>            for (i = 0; i < numres; ++i) {
>>>
>>> Hi Mario,
>>>
>>> I tested your change. boot_display becomes correct, but the issue is not fixed.
>>>
>>> The kernel state becomes:
>>>
>>>     AMD:    boot_display=1, boot_vga absent
>>>     NVIDIA: boot_display absent, boot_vga=1
>>>
>>> Current Xorg checks boot_display || boot_vga, so both GPUs still match.
>>> The selected primary GPU still depends on Xorg's DRM device enumeration order.
>>>
>>> So boot_vga is still wrong, and that still matters. The kernel should not
>>> expose boot_vga=1 for NVIDIA when the firmware framebuffer is on AMD.
>>>
>>> My patch makes boot_vga and boot_display agree on the AMD boot display.
>>>
>>> Thanks,
>>> Aaron
>>
>> Got it.  I still don't think it's correct to overload boot_vga.  It
>> would be better for us to not show boot_vga at all - because it's not
>> correct.
>>
>> Maybe we should drop the fallback code in VGA arbiter that is setting
>> NVIDIA as boot_vga at all.
>>
>> Could you look at doing that?
>>
> 
> Hi Mario,
> 
> I looked at dropping the fallback. I don't think we should remove it globally;
> old systems may still need vga_default_device() when no firmware framebuffer
> owner can be identified.
> 

What exactly happens on such old systems?  Any chance you have anything 
in your cert lab that's really old you could try?

I have to wonder if the boot_display code will work on them at least and 
we can just rely upon that.

I don't want to keep this fallback path around as tech debt if we don't 
need it and it's actively causing problems.

> For v2 I will keep the fallback, but avoid the wrong result on this system. The
> 0x0380 firmware display can become the default/boot_vga device, while legacy
> VGA decoding and ownership stay limited to pci_is_vga() devices.
> 
> So this keeps compatibility, but avoids reporting NVIDIA as boot_vga when the
> firmware framebuffer is on AMD.
> 

I'll look over the patch.