Don't attempt to reset the state of the flip-flop associated with the

vga attribute controller index or set the enable/'palette address source'
bit when saving and restoring 256 colour vga palette with 0x3c6-0x3c9 as
this does not touch the attribute registers.

When this code was ported from FreeBSD in vga.c rev 1.48 the flip-flop
reset parts were mistakenly made to read 0x3ca instead of 0x3da.

Fixes a problem with VirtualBox where the text mode background was a dim
red colour instead of black after VT switch.

Problem reported by and patch from John Carmack.

ok matthieu@ who notes this also fixes a similiar problem with a KVM /
virt-manager virtual machine.

1 files changed, 1 insertions, 7 deletions

diff --git a/sys/dev/ic/vga.c b/sys/dev/ic/vga.c
index 74cc3e07bf8..b6bc080fdfb 100644
--- a/sys/dev/ic/vga.c
+++ b/sys/dev/ic/vga.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: vga.c,v 1.69 2017/06/17 19:20:30 fcambus Exp $ */
+/* $OpenBSD: vga.c,v 1.70 2020/05/16 11:07:54 jsg Exp $ */
 /* $NetBSD: vga.c,v 1.28.2.1 2000/06/30 16:27:47 simonb Exp $ */
 
 /*-
@@ -1213,8 +1213,6 @@ vga_save_palette(struct vga_config *vc)
 	vga_raw_write(vh, VGA_DAC_READ, 0x00);
 	for (i = 0; i < 3 * 256; i++)
 		*palette++ = vga_raw_read(vh, VGA_DAC_DATA);
-
-	vga_raw_read(vh, 0x0a);			/* reset flip/flop */
 }
 
 void
@@ -1231,10 +1229,6 @@ vga_restore_palette(struct vga_config *vc)
 	vga_raw_write(vh, VGA_DAC_WRITE, 0x00);
 	for (i = 0; i < 3 * 256; i++)
 		vga_raw_write(vh, VGA_DAC_DATA, *palette++);
-
-	vga_raw_read(vh, 0x0a);			/* reset flip/flop */
-
-	vga_enable(vh);
 }
 
 void