[PATCH v2 1/1] Split VGA default device handler out of VGA arbiter

[Ard Biesheuvel]

On 24 August 2017 at 01:57, Dave Airlie <airlied at gmail.com> wrote:
>> Yeah, maybe it's time to disconnect the "default display device" idea
>> from the VGA arbiter.  I have no idea what (if any) dependencies X has
>> on the legacy VGA resources.  I assume X works fine on power, where it
>> sounds like those resources are rarely or never available.
>
> The question on non-x86 archs, is what is the correct device to default to.
>
> On x86 we use the legacy VGA resources as a pointer, as this is the device
> the BIOS appeared on at boot so hopefully should be one you can see stuff on.
>
> On non-x86 I've no idea how to decide if there are multiple devices, maybe the
> firmware needs to tag something for the kernel if there are. Otherwise
> you'd just
> be picking something in probe order.
>
> I think the idea of these patches is to separate default display
> device from the arbiter.
>
> X uses the arbiter on x86 if required (it's horrible, and it's rare we
> have to nowadays),
> but for finding the default device it justs uses the sysfs boot_vga flag.
>

Part of the problem is that X refuses to start if there is only one
display device to begin with in case it hasn't taken ownership of the
VGA legacy resources.