[coreboot] [Patch] Native VGA support.

Luc Verhaegen libv at skynet.be
Wed May 27 18:53:49 CEST 2009

On Tue, May 26, 2009 at 03:02:08PM +0200, Luc Verhaegen wrote:
> Since i have some spare time on my hands now (;)) and because ruik 
> tickled me, i dusted off some native VGA code i had sitting around since 
> 2007.
> This is only part of the solution, as the complete thing adds full 
> native vga textmodeset support for the VIA CLE266. But i am still trying 
> to track down an issue there.
> Part of the explanation of this patch is of course in the diff header, 
> so read that first, then read on here.
> Issue: kernel calls int10 set video mode, and (unless provided by 
> something else) consequently assumes that since this hook isn't 
> implemented it must be talking to a CGA device. So a message appears 
> that the vt is a CGA 80x25, and the character height is assumed to be 8.
> The real character height is 16 though, but the only effect is that you 
> have the cursor floating halfway the character, everything else is just 
> fine.
> Usage: Here is a snippet of the code in my 
> northbridge/via/vt8623/unichrome.c .init hook:
> +#if CONFIG_VGA == 1
> +	/* Now set up the VGA console */
> +	vga_io_init(); /* Enable full IO access */
> +
> +	unichrome_vga_init(dev);
> +
> +	vga_textmode_init();
> +
> +	vga_console_init();
> +#endif
> +
> +	printk_info("UniChrome VGA Textmode initialized.\n");
> +
> +	/* if we don't have console, at least print something... */
> +	vga_line_write(0, "UniChrome VGA Textmode initialized.");
> +#endif
> +
> +#endif /* CONFIG_VGA */
> TODO's in the vga console code will be dealt with. Right now i want to
> reduce my diff and make the whole more manageable.
> Luc Verhaegen.

> Implement native VGA Support.
> This code brings a rather complete set of VGA IO routines for whoever wants it.
> These consist of the by now familiar read/write/mask sets. Due to the crazy
> nature of VGA, an ancient standard with bits all over the place, it makes no
> sense to define individual registers. You need a vga register spec at hand if
> you want to do anything anyway. These IO routines are always exposed.
> It also provides code to natively set up a 640x400 VGA textmode with an 8x16
> font. The native VGA mode code is behind the OPTION_VGA option, as the font
> really adds to the size of the compiled/compressed rom. The font is the one
> also present in the linux kernel, but this file is unlicensed. Another copy of
> this is also present in coreboot in the deprecated console/btext code.
> The vga console code has been cleaned up, but it still has some TODO's left
> open, but that's for when i finally have found the remaining issue with the
> epia-m. Right now, it is important to get parts of my work out already and to
> make the remainder managable again.
> Signed-off-by: Luc Verhaegen <libv at skynet.be>

No takers?

Luc Verhaegen.

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