[PATCH] PCI/VGA: Don't assume the only VGA device on a system is `boot_vga`

[PATCH] PCI/VGA: Don't assume the only VGA device on a system is `boot_vga`

[Mario Limonciello (AMD)]

Some systems ship with multiple display class devices but not all
of them are VGA devices. If the "only" VGA device on the system is not
used for displaying the image on the screen marking it as `boot_vga`
because nothing was found is totally wrong.

This behavior actually leads to mistakes of the wrong device being
advertised to userspace and then userspace can make incorrect decisions.

As there is an accurate `boot_display` sysfs file stop lying about
`boot_vga` by assuming if nothing is found it's the right device.

Reported-by: Aaron Erhardt <aer@tuxedocomputers.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220712
Tested-by: Aaron Erhardt <aer@tuxedocomputers.com>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
---
 drivers/pci/vgaarb.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
index 436fa7f4c3873..baa242b140993 100644
--- a/drivers/pci/vgaarb.c
+++ b/drivers/pci/vgaarb.c
@@ -652,13 +652,6 @@ static bool vga_is_boot_device(struct vga_device *vgadev)
 		return true;
 	}
 
-	/*
-	 * Vgadev has neither IO nor MEM enabled.  If we haven't found any
-	 * other VGA devices, it is the best candidate so far.
-	 */
-	if (!boot_vga)
-		return true;
-
 	return false;
 }
 
-- 
2.43.0

Re: [PATCH] PCI/VGA: Don't assume the only VGA device on a system is `boot_vga`

[Bjorn Helgaas]

On Wed, Oct 29, 2025 at 01:59:33PM -0500, Mario Limonciello (AMD) wrote:
> Some systems ship with multiple display class devices but not all
> of them are VGA devices. If the "only" VGA device on the system is not
> used for displaying the image on the screen marking it as `boot_vga`
> because nothing was found is totally wrong.
> 
> This behavior actually leads to mistakes of the wrong device being
> advertised to userspace and then userspace can make incorrect decisions.
> 
> As there is an accurate `boot_display` sysfs file stop lying about
> `boot_vga` by assuming if nothing is found it's the right device.
> 
> Reported-by: Aaron Erhardt <aer@tuxedocomputers.com>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220712
> Tested-by: Aaron Erhardt <aer@tuxedocomputers.com>
> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>

Do we need a Fixes: here?  A stable cc?

The bugzilla suggests this might be a regression and hence v6.18
material?

> ---
>  drivers/pci/vgaarb.c | 7 -------
>  1 file changed, 7 deletions(-)
> 
> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
> index 436fa7f4c3873..baa242b140993 100644
> --- a/drivers/pci/vgaarb.c
> +++ b/drivers/pci/vgaarb.c
> @@ -652,13 +652,6 @@ static bool vga_is_boot_device(struct vga_device *vgadev)
>  		return true;
>  	}
>  
> -	/*
> -	 * Vgadev has neither IO nor MEM enabled.  If we haven't found any
> -	 * other VGA devices, it is the best candidate so far.
> -	 */
> -	if (!boot_vga)
> -		return true;
> -
>  	return false;
>  }
>  
> -- 
> 2.43.0
> 

Re: [PATCH] PCI/VGA: Don't assume the only VGA device on a system is `boot_vga`

[Mario Limonciello]

+Thomas

On 10/29/25 2:34 PM, Bjorn Helgaas wrote:
> On Wed, Oct 29, 2025 at 01:59:33PM -0500, Mario Limonciello (AMD) wrote:
>> Some systems ship with multiple display class devices but not all
>> of them are VGA devices. If the "only" VGA device on the system is not
>> used for displaying the image on the screen marking it as `boot_vga`
>> because nothing was found is totally wrong.
>>
>> This behavior actually leads to mistakes of the wrong device being
>> advertised to userspace and then userspace can make incorrect decisions.
>>
>> As there is an accurate `boot_display` sysfs file stop lying about
>> `boot_vga` by assuming if nothing is found it's the right device.
>>
>> Reported-by: Aaron Erhardt <aer@tuxedocomputers.com>
>> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220712
>> Tested-by: Aaron Erhardt <aer@tuxedocomputers.com>
>> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
> 
> Do we need a Fixes: here?  A stable cc?
> 
> The bugzilla suggests this might be a regression and hence v6.18
> material?

Yeah I think you're right, we should add these two tags and this should 
go to 6.18 if it's a reasonable change.

Cc: stable@vger.kernel.org
Fixes: ad90860bd10ee ("fbcon: Use screen info to find primary device")

But let's also make sure Thomas Zimmermann agrees with this change.

> 
>> ---
>>   drivers/pci/vgaarb.c | 7 -------
>>   1 file changed, 7 deletions(-)
>>
>> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
>> index 436fa7f4c3873..baa242b140993 100644
>> --- a/drivers/pci/vgaarb.c
>> +++ b/drivers/pci/vgaarb.c
>> @@ -652,13 +652,6 @@ static bool vga_is_boot_device(struct vga_device *vgadev)
>>   		return true;
>>   	}
>>   
>> -	/*
>> -	 * Vgadev has neither IO nor MEM enabled.  If we haven't found any
>> -	 * other VGA devices, it is the best candidate so far.
>> -	 */
>> -	if (!boot_vga)
>> -		return true;
>> -
>>   	return false;
>>   }
>>   
>> -- 
>> 2.43.0
>>