r269471 make unusable VT console

Nathan Whitehorn nwhitehorn at freebsd.org
Tue Aug 19 21:18:19 UTC 2014

On 08/19/14 12:02, Jean-Sébastien Pédron wrote:
> On 19.08.2014 19:46, Nathan Whitehorn wrote:
>> On 08/19/14 09:28, Jean-Sébastien Pédron wrote:
>>>       o  vt_vga introduces a new callback, vd_bitblt_text_t, which takes
>>>          as argument the text buffer, the dirty area, the font and the
>>>          cursor (position, map, colors).
>> Why is this necessary? I'd really prefer to avoid complicating this API.
>> One of the great things about writing newcons drivers is that there is
>> basically only one function you need to implement. If the current API
>> does not provide enough information to do this efficiently, I'd much
>> rather change it than add new callbacks.
> I don't want to have two callbacks for the same feature either, and I'd
> like to transition other drivers to this new one.
> The current bitbltchr callback only knows about one character. In the
> case of vt_vga, if this character (or the cursor) isn't aligned on
> 8-pixels boundaries, it needs to redraw several "blocks" of pixels. With
> this character-centric approach, if a block needs a redraw, it'll be
> refreshed for the character on its left side, then refreshed again for
> the character on its right side.
> The advantage of giving the callback the whole text/area is that it
> allows the driver to manipulate the pixels block by block, instead of
> character by character.
> The patch isn't finished yet. Meanwhile, I'll commit the bug fixes I
> made (especially the cursor handling in vt_flush()). But eventually, the
> plan is to convert all drivers to this new callback, if you find the new
> API sensible.

That sounds great. There are only a few (3?) discrete implementations of 
bitbltchr in the tree right now, so the conversion should be easy.

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