[systemd-devel] [PATCH 1/1] graphics: Do not require nonstandard console control protocol

[Tom Gundersen]

On Wed, Jan 15, 2014 at 3:55 PM, Joonas Lahtinen
<joonas.lahtinen at linux.intel.com> wrote:
> On 15.01.2014 13:34, Tom Gundersen wrote:
>>
>> On Wed, Jan 15, 2014 at 12:08 PM, Joonas Lahtinen
>> <joonas.lahtinen at linux.intel.com> wrote:
>>>
>>> Console Control Protocol is a nonstandard UEFI interface and lack of
>>> it shall not be treated as an error.
>>
>> Ah, great! I was struggling to make the splash work on tianocore for
>> the longest time, and this fixes it indeed.
>>
>> Applied and pushed.
>
>
> Great that it helped. The same goes for other implementations too.
>
>
>> Only minor issue left now is that we need to explicitly clear the
>> screen before writing in console mode (as can be seen if you boot into
>> tianocore and press 'P' followed by any other keys to switch between
>> the modes). Care to take a look at that?
>
>
> I think it is more by design than a bug, as now the graphics mode switch
> function does nothing. There's no telling the UEFI implementation if you
> want to draw text or graphics. I've seen multiple implementations in some
> Windows bootloader leaves some text on screen behind logo, and others where
> only cursor is seen, and in rare case the background is completely black.
> It's just not specified by standard (or at least not implemented widely), if
> the text output should cause screen to clear.
>
> Fbcon behaves pretty much the same way, the graphics get overwritten by the
> text, and the text continues from where it left off, independent of each
> other. So it's up to the application to enforce screen clearing if they want
> to.
>
> One simple solution to ensure uniform behaviour across implementations could
> be to do explicit clear on the screen and home the cursor to upper left
> always when a text mode is requested. And vice versa, clear screen when
> graphics mode is requested.
>
> Was this the problem you meant?

Yeah, that's what I had in mind. I guess it only is a "problem" in the
debug case, but still uniformity would be good.

-t