1 =============== 1 ===============
2 What is vesafb? 2 What is vesafb?
3 =============== 3 ===============
4 4
5 This is a generic driver for a graphic framebu 5 This is a generic driver for a graphic framebuffer on intel boxes.
6 6
7 The idea is simple: Turn on graphics mode at 7 The idea is simple: Turn on graphics mode at boot time with the help
8 of the BIOS, and use this as framebuffer devic 8 of the BIOS, and use this as framebuffer device /dev/fb0, like the m68k
9 (and other) ports do. 9 (and other) ports do.
10 10
11 This means we decide at boot time whenever we 11 This means we decide at boot time whenever we want to run in text or
12 graphics mode. Switching mode later on (in pr 12 graphics mode. Switching mode later on (in protected mode) is
13 impossible; BIOS calls work in real mode only. 13 impossible; BIOS calls work in real mode only. VESA BIOS Extensions
14 Version 2.0 are required, because we need a li 14 Version 2.0 are required, because we need a linear frame buffer.
15 15
16 Advantages: 16 Advantages:
17 17
18 * It provides a nice large console (128 cols 18 * It provides a nice large console (128 cols + 48 lines with 1024x768)
19 without using tiny, unreadable fonts. 19 without using tiny, unreadable fonts.
20 * You can run XF68_FBDev on top of /dev/fb0 ( 20 * You can run XF68_FBDev on top of /dev/fb0 (=> non-accelerated X11
21 support for every VBE 2.0 compliant graphic 21 support for every VBE 2.0 compliant graphics board).
22 * Most important: boot logo :-) 22 * Most important: boot logo :-)
23 23
24 Disadvantages: 24 Disadvantages:
25 25
26 * graphic mode is slower than text mode... 26 * graphic mode is slower than text mode...
27 27
28 28
29 How to use it? 29 How to use it?
30 ============== 30 ==============
31 31
32 Switching modes is done using the vga=... boot 32 Switching modes is done using the vga=... boot parameter. Read
33 Documentation/admin-guide/svga.rst for details 33 Documentation/admin-guide/svga.rst for details.
34 34
35 You should compile in both vgacon (for text mo 35 You should compile in both vgacon (for text mode) and vesafb (for
36 graphics mode). Which of them takes over the c 36 graphics mode). Which of them takes over the console depends on
37 whenever the specified mode is text or graphic 37 whenever the specified mode is text or graphics.
38 38
39 The graphic modes are NOT in the list which yo 39 The graphic modes are NOT in the list which you get if you boot with
40 vga=ask and hit return. The mode you wish to u 40 vga=ask and hit return. The mode you wish to use is derived from the
41 VESA mode number. Here are those VESA mode num 41 VESA mode number. Here are those VESA mode numbers:
42 42
43 ====== ======= ======= ======== ========= 43 ====== ======= ======= ======== =========
44 colors 640x480 800x600 1024x768 1280x1024 44 colors 640x480 800x600 1024x768 1280x1024
45 ====== ======= ======= ======== ========= 45 ====== ======= ======= ======== =========
46 256 0x101 0x103 0x105 0x107 46 256 0x101 0x103 0x105 0x107
47 32k 0x110 0x113 0x116 0x119 47 32k 0x110 0x113 0x116 0x119
48 64k 0x111 0x114 0x117 0x11A 48 64k 0x111 0x114 0x117 0x11A
49 16M 0x112 0x115 0x118 0x11B 49 16M 0x112 0x115 0x118 0x11B
50 ====== ======= ======= ======== ========= 50 ====== ======= ======= ======== =========
51 51
52 52
53 The video mode number of the Linux kernel is t 53 The video mode number of the Linux kernel is the VESA mode number plus
54 0x200: 54 0x200:
55 55
56 Linux_kernel_mode_number = VESA_mode_number + 56 Linux_kernel_mode_number = VESA_mode_number + 0x200
57 57
58 So the table for the Kernel mode numbers are: 58 So the table for the Kernel mode numbers are:
59 59
60 ====== ======= ======= ======== ========= 60 ====== ======= ======= ======== =========
61 colors 640x480 800x600 1024x768 1280x1024 61 colors 640x480 800x600 1024x768 1280x1024
62 ====== ======= ======= ======== ========= 62 ====== ======= ======= ======== =========
63 256 0x301 0x303 0x305 0x307 63 256 0x301 0x303 0x305 0x307
64 32k 0x310 0x313 0x316 0x319 64 32k 0x310 0x313 0x316 0x319
65 64k 0x311 0x314 0x317 0x31A 65 64k 0x311 0x314 0x317 0x31A
66 16M 0x312 0x315 0x318 0x31B 66 16M 0x312 0x315 0x318 0x31B
67 ====== ======= ======= ======== ========= 67 ====== ======= ======= ======== =========
68 68
69 To enable one of those modes you have to speci 69 To enable one of those modes you have to specify "vga=ask" in the
70 lilo.conf file and rerun LILO. Then you can ty 70 lilo.conf file and rerun LILO. Then you can type in the desired
71 mode at the "vga=ask" prompt. For example if y 71 mode at the "vga=ask" prompt. For example if you like to use
72 1024x768x256 colors you have to say "305" at t 72 1024x768x256 colors you have to say "305" at this prompt.
73 73
74 If this does not work, this might be because y 74 If this does not work, this might be because your BIOS does not support
75 linear framebuffers or because it does not sup 75 linear framebuffers or because it does not support this mode at all.
76 Even if your board does, it might be the BIOS 76 Even if your board does, it might be the BIOS which does not. VESA BIOS
77 Extensions v2.0 are required, 1.2 is NOT suffi 77 Extensions v2.0 are required, 1.2 is NOT sufficient. You will get a
78 "bad mode number" message if something goes wr 78 "bad mode number" message if something goes wrong.
79 79
80 1. Note: LILO cannot handle hex, for booting d 80 1. Note: LILO cannot handle hex, for booting directly with
81 "vga=mode-number" you have to transform the 81 "vga=mode-number" you have to transform the numbers to decimal.
82 2. Note: Some newer versions of LILO appear to 82 2. Note: Some newer versions of LILO appear to work with those hex values,
83 if you set the 0x in front of the numbers. 83 if you set the 0x in front of the numbers.
84 84
85 X11 85 X11
86 === 86 ===
87 87
88 XF68_FBDev should work just fine, but it is no 88 XF68_FBDev should work just fine, but it is non-accelerated. Running
89 another (accelerated) X-Server like XF86_SVGA 89 another (accelerated) X-Server like XF86_SVGA might or might not work.
90 It depends on X-Server and graphics board. 90 It depends on X-Server and graphics board.
91 91
92 The X-Server must restore the video mode corre 92 The X-Server must restore the video mode correctly, else you end up
93 with a broken console (and vesafb cannot do an 93 with a broken console (and vesafb cannot do anything about this).
94 94
95 95
96 Refresh rates 96 Refresh rates
97 ============= 97 =============
98 98
99 There is no way to change the vesafb video mod 99 There is no way to change the vesafb video mode and/or timings after
100 booting linux. If you are not happy with the 100 booting linux. If you are not happy with the 60 Hz refresh rate, you
101 have these options: 101 have these options:
102 102
103 * configure and load the DOS-Tools for the gr 103 * configure and load the DOS-Tools for the graphics board (if
104 available) and boot linux with loadlin. 104 available) and boot linux with loadlin.
105 * use a native driver (matroxfb/atyfb) instea 105 * use a native driver (matroxfb/atyfb) instead if vesafb. If none
106 is available, write a new one! 106 is available, write a new one!
107 * VBE 3.0 might work too. I have neither a g 107 * VBE 3.0 might work too. I have neither a gfx board with VBE 3.0
108 support nor the specs, so I have not checke 108 support nor the specs, so I have not checked this yet.
109 109
110 110
111 Configuration 111 Configuration
112 ============= 112 =============
113 113
114 The VESA BIOS provides protected mode interfac 114 The VESA BIOS provides protected mode interface for changing
115 some parameters. vesafb can use it for palett 115 some parameters. vesafb can use it for palette changes and
116 to pan the display. It is turned off by defau 116 to pan the display. It is turned off by default because it
117 seems not to work with some BIOS versions, but 117 seems not to work with some BIOS versions, but there are options
118 to turn it on. 118 to turn it on.
119 119
120 You can pass options to vesafb using "video=ve 120 You can pass options to vesafb using "video=vesafb:option" on
121 the kernel command line. Multiple options sho 121 the kernel command line. Multiple options should be separated
122 by comma, like this: "video=vesafb:ypan,invers 122 by comma, like this: "video=vesafb:ypan,inverse"
123 123
124 Accepted options: 124 Accepted options:
125 125
126 inverse use inverse color map 126 inverse use inverse color map
127 127
128 ========= ==================================== 128 ========= ======================================================================
129 ypan enable display panning using the VES 129 ypan enable display panning using the VESA protected mode
130 interface. The visible screen is ju 130 interface. The visible screen is just a window of the
131 video memory, console scrolling is d 131 video memory, console scrolling is done by changing the
132 start of the window. 132 start of the window.
133 133
134 pro: 134 pro:
135 135
136 * scrolling (fullscreen) is fa 136 * scrolling (fullscreen) is fast, because there is
137 no need to copy around data. 137 no need to copy around data.
138 138
139 kontra: 139 kontra:
140 140
141 * scrolling only parts of the 141 * scrolling only parts of the screen causes some
142 ugly flicker effects (boot l 142 ugly flicker effects (boot logo flickers for
143 example). 143 example).
144 144
145 ywrap Same as ypan, but assumes your gfx b 145 ywrap Same as ypan, but assumes your gfx board can wrap-around
146 the video memory (i.e. starts readin 146 the video memory (i.e. starts reading from top if it
147 reaches the end of video memory). F 147 reaches the end of video memory). Faster than ypan.
148 148
149 redraw Scroll by redrawing the affected par 149 redraw Scroll by redrawing the affected part of the screen, this
150 is the safe (and slow) default. 150 is the safe (and slow) default.
151 151
152 152
153 vgapal Use the standard vga registers for p 153 vgapal Use the standard vga registers for palette changes.
154 This is the default. 154 This is the default.
155 pmipal Use the protected mode interface for 155 pmipal Use the protected mode interface for palette changes.
156 156
157 mtrr:n Setup memory type range registers fo 157 mtrr:n Setup memory type range registers for the vesafb framebuffer
158 where n: 158 where n:
159 159
160 - 0 - disabled (equivalent to no 160 - 0 - disabled (equivalent to nomtrr) (default)
161 - 1 - uncachable 161 - 1 - uncachable
162 - 2 - write-back 162 - 2 - write-back
163 - 3 - write-combining 163 - 3 - write-combining
164 - 4 - write-through 164 - 4 - write-through
165 165
166 If you see the following in dmesg, c 166 If you see the following in dmesg, choose the type that matches the
167 old one. In this example, use "mtrr: 167 old one. In this example, use "mtrr:2".
168 ... 168 ...
169 mtrr: type mismatch for e0000000,8000000 o 169 mtrr: type mismatch for e0000000,8000000 old: write-back new:
170 write-combining 170 write-combining
171 ... 171 ...
172 172
173 nomtrr disable mtrr 173 nomtrr disable mtrr
174 174
175 vremap:n 175 vremap:n
176 Remap 'n' MiB of video RAM. If 0 or 176 Remap 'n' MiB of video RAM. If 0 or not specified, remap memory
177 according to video mode. (2.5.66 pat 177 according to video mode. (2.5.66 patch/idea by Antonino Daplas
178 reversed to give override possibilit 178 reversed to give override possibility (allocate more fb memory
179 than the kernel would) to 2.4 by tmb 179 than the kernel would) to 2.4 by tmb@iki.fi)
180 180
181 vtotal:n If the video BIOS of your card incor 181 vtotal:n If the video BIOS of your card incorrectly determines the total
182 amount of video RAM, use this option 182 amount of video RAM, use this option to override the BIOS (in MiB).
183 ========= ==================================== 183 ========= ======================================================================
184 184
185 Have fun! 185 Have fun!
186 186
187 Gerd Knorr <kraxel@goldbach.in-berlin.de> 187 Gerd Knorr <kraxel@goldbach.in-berlin.de>
188 188
189 Minor (mostly typo) changes 189 Minor (mostly typo) changes
190 by Nico Schmoigl <schmoigl@rumms.uni-mannheim.d 190 by Nico Schmoigl <schmoigl@rumms.uni-mannheim.de>
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