com32/mboot/initvesa.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1999-2008 H. Peter Anvin - All Rights Reserved
   4  *   Copyright 2009 Intel Corporation; author: H. Peter Anvin
   5  *
   6  *   Permission is hereby granted, free of charge, to any person
   7  *   obtaining a copy of this software and associated documentation
   8  *   files (the "Software"), to deal in the Software without
   9  *   restriction, including without limitation the rights to use,
  10  *   copy, modify, merge, publish, distribute, sublicense, and/or
  11  *   sell copies of the Software, and to permit persons to whom
  12  *   the Software is furnished to do so, subject to the following
  13  *   conditions:
  14  *
  15  *   The above copyright notice and this permission notice shall
  16  *   be included in all copies or substantial portions of the Software.
  17  *
  18  *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  19  *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  20  *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  21  *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  22  *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  23  *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  24  *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  25  *   OTHER DEALINGS IN THE SOFTWARE.
  26  *
  27  * ----------------------------------------------------------------------- */
  28
  29 /*
  30  * initvesa.c
  31  *
  32  * Query the VESA BIOS and select a 640x480x32 mode with local mapping
  33  * support, if one exists.
  34  */
  35
  36 #include <inttypes.h>
  37 #include <com32.h>
  38 #include <stdlib.h>
  39 #include <string.h>
  40 #include <limits.h>
  41
  42 #include "vesa.h"
  43 #include "mboot.h"
  44
  45 struct vesa_info vesa_info;
  46
  47 void set_graphics_mode(const struct multiboot_header *mbh,
  48                        struct multiboot_info *mbi)
  49 {
  50     com32sys_t rm;
  51     uint16_t mode, bestmode, *mode_ptr;
  52     struct vesa_general_info *gi;
  53     struct vesa_mode_info *mi;
  54     int pxf, bestpxf;
  55     int wantx, wanty;
  56     int err, besterr;
  57     bool better;
  58     addr_t viaddr;
  59
  60     /* Only do this if requested by the OS image */
  61     if (!(mbh->flags & MULTIBOOT_VIDEO_MODE) || mbh->mode_type != 0)
  62         return;
  63
  64     /* Allocate space in the bounce buffer for these structures */
  65     gi = &((struct vesa_info *)__com32.cs_bounce)->gi;
  66     mi = &((struct vesa_info *)__com32.cs_bounce)->mi;
  67
  68     memset(&rm, 0, sizeof rm);
  69     memset(gi, 0, sizeof *gi);
  70
  71     gi->signature = VBE2_MAGIC; /* Get VBE2 extended data */
  72     rm.eax.w[0] = 0x4F00;       /* Get SVGA general information */
  73     rm.edi.w[0] = OFFS(gi);
  74     rm.es = SEG(gi);
  75     __intcall(0x10, &rm, &rm);
  76
  77     if (rm.eax.w[0] != 0x004F)
  78         return;                 /* Function call failed */
  79     if (gi->signature != VESA_MAGIC)
  80         return;                 /* No magic */
  81     if (gi->version < 0x0102)
  82         return;                 /* VESA 1.2+ required */
  83
  84     memcpy(&vesa_info.gi, gi, sizeof *gi);
  85
  86     /* Search for a suitable mode with a suitable color and memory model... */
  87
  88     mode_ptr = GET_PTR(gi->video_mode_ptr);
  89     bestmode = 0;
  90     bestpxf = 0;
  91     wantx = mbh->width  ? mbh->width  : 0xffff;
  92     wanty = mbh->height ? mbh->height : 0xffff;
  93     besterr = wantx + wanty;
  94
  95     while ((mode = *mode_ptr++) != 0xFFFF) {
  96         mode &= 0x1FF;          /* The rest are attributes of sorts */
  97
  98         memset(mi, 0, sizeof *mi);
  99         rm.eax.w[0] = 0x4F01;   /* Get SVGA mode information */
 100         rm.ecx.w[0] = mode;
 101         rm.edi.w[0] = OFFS(mi);
 102         rm.es = SEG(mi);
 103         __intcall(0x10, &rm, &rm);
 104
 105         /* Must be a supported mode */
 106         if (rm.eax.w[0] != 0x004f)
 107             continue;
 108
 109         /* Must be an LFB color graphics mode supported by the hardware.
 110
 111            The bits tested are:
 112            7 - linear frame buffer
 113            4 - graphics mode
 114            3 - color mode
 115            1 - mode information available (mandatory in VBE 1.2+)
 116            0 - mode supported by hardware
 117          */
 118         if ((mi->mode_attr & 0x009b) != 0x009b)
 119             continue;
 120
 121         /* We don't support multibank (interlaced memory) modes */
 122         /*
 123          *  Note: The Bochs VESA BIOS (vbe.c 1.58 2006/08/19) violates the
 124          * specification which states that banks == 1 for unbanked modes;
 125          * fortunately it does report bank_size == 0 for those.
 126          */
 127         if (mi->banks > 1 && mi->bank_size)
 128             continue;
 129
 130         /* Must either be a packed-pixel mode or a direct color mode
 131            (depending on VESA version ); must be a supported pixel format */
 132
 133         if (mi->bpp == 32 &&
 134             (mi->memory_layout == 4 ||
 135              (mi->memory_layout == 6 && mi->rpos == 16 && mi->gpos == 8 &&
 136               mi->bpos == 0)))
 137             pxf = 32;
 138         else if (mi->bpp == 24 &&
 139                  (mi->memory_layout == 4 ||
 140                   (mi->memory_layout == 6 && mi->rpos == 16 && mi->gpos == 8 &&
 141                    mi->bpos == 0)))
 142             pxf = 24;
 143         else if (mi->bpp == 16 &&
 144                  (mi->memory_layout == 4 ||
 145                   (mi->memory_layout == 6 && mi->rpos == 11 && mi->gpos == 5 &&
 146                    mi->bpos == 0)))
 147             pxf = 16;
 148         else if (mi->bpp == 15 &&
 149                  (mi->memory_layout == 4 ||
 150                   (mi->memory_layout == 6 && mi->rpos == 10 && mi->gpos == 5 &&
 151                    mi->bpos == 0)))
 152             pxf = 15;
 153         else
 154             continue;
 155
 156         better = false;
 157         err = abs(mi->h_res - wantx) + abs(mi->v_res - wanty);
 158
 159 #define IS_GOOD(mi, bestx, besty) \
 160         ((mi)->h_res >= (bestx) && (mi)->v_res >= (besty))
 161
 162         if (!bestpxf)
 163             better = true;
 164         else if (!IS_GOOD(&vesa_info.mi, wantx, wanty) &&
 165                  IS_GOOD(mi, wantx, wanty))
 166             /* This matches criteria, which the previous one didn't */
 167             better = true;
 168         else if (IS_GOOD(&vesa_info.mi, wantx, wanty) &&
 169                  !IS_GOOD(mi, wantx, wanty))
 170             /* This doesn't match criteria, and the previous one did */
 171             better = false;
 172         else if (err < besterr)
 173             better = true;
 174         else if (err == besterr && (pxf == (int)mbh->depth || pxf > bestpxf))
 175             better = true;
 176
 177         if (better) {
 178             bestmode = mode;
 179             bestpxf = pxf;
 180             memcpy(&vesa_info.mi, mi, sizeof *mi);
 181         }
 182     }
 183
 184     if (!bestpxf)
 185         return;                 /* No mode found */
 186
 187     mi = &vesa_info.mi;
 188     mode = bestmode;
 189
 190     /* Now set video mode */
 191     rm.eax.w[0] = 0x4F02;       /* Set SVGA video mode */
 192     mode |= 0x4000;             /* Request linear framebuffer */
 193     rm.ebx.w[0] = mode;
 194     __intcall(0x10, &rm, &rm);
 195     if (rm.eax.w[0] != 0x004F)
 196         return;                 /* Failed to set mode */
 197
 198     mbi->flags |= MB_INFO_VIDEO_INFO;
 199     mbi->vbe_mode = mode;
 200     viaddr = map_data(&vesa_info, sizeof vesa_info, 4, 0);
 201     mbi->vbe_control_info = viaddr + offsetof(struct vesa_info, gi);
 202     mbi->vbe_mode_info = viaddr + offsetof(struct vesa_info, mi);
 203
 204     /* Get the VBE 2.x PM entry point if supported */
 205     rm.eax.w[0] = 0x4F0A;
 206     rm.ebx.w[0] = 0;
 207     __intcall(0x10, &rm, &rm);
 208     if (rm.eax.w[0] == 0x004F) {
 209         mbi->vbe_interface_seg = rm.es;
 210         mbi->vbe_interface_off = rm.edi.w[0];
 211         mbi->vbe_interface_len = rm.ecx.w[0];
 212     }
 213
 214     /* Tell syslinux we changed video mode */
 215     rm.eax.w[0] = 0x0017;       /* Report video mode change */
 216     /* In theory this should be:
 217
 218        rm.ebx.w[0] = (mi->mode_attr & 4) ? 0x0007 : 0x000f;
 219
 220        However, that would assume all systems that claim to handle text
 221        output in VESA modes actually do that... */
 222     rm.ebx.w[0] = 0x000f;
 223     rm.ecx.w[0] = vesa_info.mi.h_res;
 224     rm.edx.w[0] = vesa_info.mi.v_res;
 225     __intcall(0x22, &rm, NULL);
 226 }