Commit 8e92dc76 authored Feb 19, 2010 by H. Peter Anvin

x86, setup: Don't skip mode setting for the standard VGA modes



The code for setting standard VGA modes probes for the current mode,
and skips the mode setting if the mode is 3 (color text 80x25) or 7
(mono text 80x25).  Unfortunately, there are BIOSes, including the
VMware BIOS, which report the previous mode if function 0F is queried
while the screen is in a VESA mode, and of course, nothing can help a
mode poked directly into the hardware.

As such, the safe option is to set the mode anyway, and only query to
see if we should be using mode 7 rather than mode 3.  People who don't
want any mode setting at all should probably use vga=0x0f04
(VIDEO_CURRENT_MODE).  It's possible that should be the kernel
default.

Reported-by Rene Arends <R.R.Arends@hro.nl>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <tip-*@git.kernel.org>

parent eb572a5c

arch/x86/boot/video-vga.c

+1 −8

Original line number	Diff line number	Diff line
		@@ -42,22 +42,15 @@ static u8 vga_set_basic_mode(void)
		{
		struct biosregs ireg, oreg;
		u16 ax;
		u8 rows;
		u8 mode;

		initregs(&ireg);

		/* Query current mode */
		ax = 0x0f00;
		intcall(0x10, &ireg, &oreg);
		mode = oreg.al;

		set_fs(0);
		rows = rdfs8(0x484); /* rows minus one */

		if ((oreg.ax == 0x5003 \|\| oreg.ax == 0x5007) &&
		(rows == 0 \|\| rows == 24))
		return mode;

		if (mode != 3 && mode != 7)
		mode = 3;