"H. Peter Anvin" <[EMAIL PROTECTED]> writes:

> Andrew Morton wrote:
>> On Thu, 05 Oct 2006 00:13:12 -0600
>> [EMAIL PROTECTED] (Eric W. Biederman) wrote:
>>
>>> Do things work better if you don't specify a vga=xxx mode?
>> yes, without vga=0x263 it boots.
>
> vga= actually patches a specific offset in the boot sector.  We don't actually
> have 512 bytes, we have some 500-ish bytes plus a small patch area at the end.

>From video.S
It uses offset 0 in the boot sector.  We have 497 bytes that can be used,
before we call setup.S after that setup.S considers the entire bootsector
it's own.

/* Positions of various video parameters passed to the kernel */
/* (see also include/linux/tty.h) */
#define PARAM_CURSOR_POS        0x00
#define PARAM_VIDEO_PAGE        0x04
#define PARAM_VIDEO_MODE        0x06
#define PARAM_VIDEO_COLS        0x07
#define PARAM_VIDEO_EGA_BX      0x0a
#define PARAM_VIDEO_LINES       0x0e
#define PARAM_HAVE_VGA          0x0f
#define PARAM_FONT_POINTS       0x10

#define PARAM_LFB_WIDTH         0x12
#define PARAM_LFB_HEIGHT        0x14
#define PARAM_LFB_DEPTH         0x16
#define PARAM_LFB_BASE          0x18
#define PARAM_LFB_SIZE          0x1c
#define PARAM_LFB_LINELENGTH    0x24
#define PARAM_LFB_COLORS        0x26
#define PARAM_VESAPM_SEG        0x2e
#define PARAM_VESAPM_OFF        0x30
#define PARAM_LFB_PAGES         0x32
#define PARAM_VESA_ATTRIB       0x34
#define PARAM_CAPABILITIES      0x36

Eric
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