Re: [PATCH] Kernel fbcon UNICODE font support

From: James Simmons
Date: Thu Dec 02 2010 - 08:50:41 EST



> 在 2010-11-28日的 09:15 +0100,Vojtech Pavlik写道:
> >
> > Well, on VGA you could use the 512 glyphs available (9 bit character, 7
> > bit attribute) and dynamically change the font in the video memory to
> > always contain the characters that you need on the screen. Chances are
> > that you won't need all 512 at any single time. The screen isn't that
> > large in classic VGA mode.
> >
> > But since VGA is mostly dead these days anyway, it'd be a neat hack, but
> > probably not worth the effort.
>
> Can't do that. That's too tricky, and some times we *DO* need more than
> 512 different glyphs.

BTW the console developement branch is at

git://git.infradead.org/~jsimmons/public_git/linuxconsole-2.6.git

I have managed to do massive cleanup to the console layer but its not
quite ready for general testing. Its mostly working but there are still
some major bugs. As for the VC screen buffers the issue is that the default
screen buffers where based on the VGA text mode. In fact the visible VC for
vgacon is the actually vga video buffer. When we do a VT switch it copys
the video buffer to a software buffer and then loads the vga video buffer
with the VCs software buffer we switched to.
This is nice and neat for vgacon but it doesn't flow so nicely with
graphical consoles or text LCDs. What I like to see is the attribute
buffer be split from the vc_screenbuf. The bonus is in embbeded systems we
could arrange the code so we could have a light weight printk VT without
the extra junk of the VC. Do we really need a attribute buffer for printk?
I believe that would be the first step in the right direction.