On Sun, Dec 01, 2002 at 10:05:21AM -0700, Ronald G. Minnich wrote:
I see no problem with putting vsa2 to rom. I just don't know how to use it :-)
E.g. via int 10h, or outb(0x220,..).. VSA (and 2) is used to provide the old software interface to the new hardware that works in quite different (better, hopefully) ways.
When int 10h is called, or port 0x220 or 0x92 is accessed, an smint (system management interrupt, found on mobile CPUs for suspending and so on) is generated and the "low level" OS driver ends up talking to software instead of hardware. Practical and economic, when you grasp the concept.
Some VSA things are complete functions (xpressaudio, no sound will be heard without the xpressaudio VSA ROM) while others are only one way to access that particular feature (video BIOS, the framebuffer driver works as well which means that the video BIOS isn't strictly needed although nice for boot debugging) and yet others may be simple, optional, addons.
//Peter