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0a0b53f6 MJ |
1 | |
2 | uvesafb - A Generic Driver for VBE2+ compliant video cards | |
3 | ========================================================== | |
4 | ||
5 | 1. Requirements | |
6 | --------------- | |
7 | ||
8 | uvesafb should work with any video card that has a Video BIOS compliant | |
9 | with the VBE 2.0 standard. | |
10 | ||
11 | Unlike other drivers, uvesafb makes use of a userspace helper called | |
12 | v86d. v86d is used to run the x86 Video BIOS code in a simulated and | |
13 | controlled environment. This allows uvesafb to function on arches other | |
14 | than x86. Check the v86d documentation for a list of currently supported | |
15 | arches. | |
16 | ||
17 | v86d source code can be downloaded from the following website: | |
18 | http://dev.gentoo.org/~spock/projects/uvesafb | |
19 | ||
20 | Please refer to the v86d documentation for detailed configuration and | |
21 | installation instructions. | |
22 | ||
23 | Note that the v86d userspace helper has to be available at all times in | |
24 | order for uvesafb to work properly. If you want to use uvesafb during | |
25 | early boot, you will have to include v86d into an initramfs image, and | |
26 | either compile it into the kernel or use it as an initrd. | |
27 | ||
28 | 2. Caveats and limitations | |
29 | -------------------------- | |
30 | ||
31 | uvesafb is a _generic_ driver which supports a wide variety of video | |
32 | cards, but which is ultimately limited by the Video BIOS interface. | |
33 | The most important limitations are: | |
34 | ||
35 | - Lack of any type of acceleration. | |
36 | - A strict and limited set of supported video modes. Often the native | |
37 | or most optimal resolution/refresh rate for your setup will not work | |
38 | with uvesafb, simply because the Video BIOS doesn't support the | |
39 | video mode you want to use. This can be especially painful with | |
40 | widescreen panels, where native video modes don't have the 4:3 aspect | |
41 | ratio, which is what most BIOS-es are limited to. | |
42 | - Adjusting the refresh rate is only possible with a VBE 3.0 compliant | |
43 | Video BIOS. Note that many nVidia Video BIOS-es claim to be VBE 3.0 | |
44 | compliant, while they simply ignore any refresh rate settings. | |
45 | ||
46 | 3. Configuration | |
47 | ---------------- | |
48 | ||
49 | uvesafb can be compiled either as a module, or directly into the kernel. | |
50 | In both cases it supports the same set of configuration options, which | |
51 | are either given on the kernel command line or as module parameters, e.g.: | |
52 | ||
53 | video=uvesafb:1024x768-32,mtrr:3,ywrap (compiled into the kernel) | |
54 | ||
55 | # modprobe uvesafb mode=1024x768-32 mtrr=3 scroll=ywrap (module) | |
56 | ||
57 | Accepted options: | |
58 | ||
59 | ypan Enable display panning using the VESA protected mode | |
60 | interface. The visible screen is just a window of the | |
61 | video memory, console scrolling is done by changing the | |
62 | start of the window. Available on x86 only. | |
63 | ||
64 | ywrap Same as ypan, but assumes your gfx board can wrap-around | |
65 | the video memory (i.e. starts reading from top if it | |
66 | reaches the end of video memory). Faster than ypan. | |
67 | Available on x86 only. | |
68 | ||
69 | redraw Scroll by redrawing the affected part of the screen, this | |
70 | is the safe (and slow) default. | |
71 | ||
72 | (If you're using uvesafb as a module, the above three options are | |
73 | used a parameter of the scroll option, e.g. scroll=ypan.) | |
74 | ||
75 | vgapal Use the standard VGA registers for palette changes. | |
76 | ||
77 | pmipal Use the protected mode interface for palette changes. | |
78 | This is the default if the protected mode interface is | |
79 | available. Available on x86 only. | |
80 | ||
81 | mtrr:n Setup memory type range registers for the framebuffer | |
82 | where n: | |
83 | 0 - disabled (equivalent to nomtrr) (default) | |
84 | 1 - uncachable | |
85 | 2 - write-back | |
86 | 3 - write-combining | |
87 | 4 - write-through | |
88 | ||
89 | If you see the following in dmesg, choose the type that matches | |
90 | the old one. In this example, use "mtrr:2". | |
91 | ... | |
92 | mtrr: type mismatch for e0000000,8000000 old: write-back new: write-combining | |
93 | ... | |
94 | ||
95 | nomtrr Do not use memory type range registers. | |
96 | ||
97 | vremap:n | |
98 | Remap 'n' MiB of video RAM. If 0 or not specified, remap memory | |
99 | according to video mode. | |
100 | ||
101 | vtotal:n | |
102 | If the video BIOS of your card incorrectly determines the total | |
103 | amount of video RAM, use this option to override the BIOS (in MiB). | |
104 | ||
105 | <mode> The mode you want to set, in the standard modedb format. Refer to | |
106 | modedb.txt for a detailed description. When uvesafb is compiled as | |
107 | a module, the mode string should be provided as a value of the | |
108 | 'mode' option. | |
109 | ||
110 | vbemode:x | |
111 | Force the use of VBE mode x. The mode will only be set if it's | |
112 | found in the VBE-provided list of supported modes. | |
113 | NOTE: The mode number 'x' should be specified in VESA mode number | |
114 | notation, not the Linux kernel one (eg. 257 instead of 769). | |
115 | HINT: If you use this option because normal <mode> parameter does | |
116 | not work for you and you use a X server, you'll probably want to | |
117 | set the 'nocrtc' option to ensure that the video mode is properly | |
118 | restored after console <-> X switches. | |
119 | ||
120 | nocrtc Do not use CRTC timings while setting the video mode. This option | |
121 | has any effect only if the Video BIOS is VBE 3.0 compliant. Use it | |
122 | if you have problems with modes set the standard way. Note that | |
123 | using this option implies that any refresh rate adjustments will | |
124 | be ignored and the refresh rate will stay at your BIOS default (60 Hz). | |
125 | ||
126 | noedid Do not try to fetch and use EDID-provided modes. | |
127 | ||
128 | noblank Disable hardware blanking. | |
129 | ||
130 | v86d:path | |
131 | Set path to the v86d executable. This option is only available as | |
132 | a module parameter, and not as a part of the video= string. If you | |
133 | need to use it and have uvesafb built into the kernel, use | |
134 | uvesafb.v86d="path". | |
135 | ||
136 | Additionally, the following parameters may be provided. They all override the | |
137 | EDID-provided values and BIOS defaults. Refer to your monitor's specs to get | |
138 | the correct values for maxhf, maxvf and maxclk for your hardware. | |
139 | ||
140 | maxhf:n Maximum horizontal frequency (in kHz). | |
141 | maxvf:n Maximum vertical frequency (in Hz). | |
142 | maxclk:n Maximum pixel clock (in MHz). | |
143 | ||
144 | 4. The sysfs interface | |
145 | ---------------------- | |
146 | ||
147 | uvesafb provides several sysfs nodes for configurable parameters and | |
148 | additional information. | |
149 | ||
150 | Driver attributes: | |
151 | ||
152 | /sys/bus/platform/drivers/uvesafb | |
153 | - v86d (default: /sbin/v86d) | |
154 | Path to the v86d executable. v86d is started by uvesafb | |
155 | if an instance of the daemon isn't already running. | |
156 | ||
157 | Device attributes: | |
158 | ||
159 | /sys/bus/platform/drivers/uvesafb/uvesafb.0 | |
160 | - nocrtc | |
161 | Use the default refresh rate (60 Hz) if set to 1. | |
162 | ||
163 | - oem_product_name | |
164 | - oem_product_rev | |
165 | - oem_string | |
166 | - oem_vendor | |
167 | Information about the card and its maker. | |
168 | ||
169 | - vbe_modes | |
170 | A list of video modes supported by the Video BIOS along with their | |
171 | VBE mode numbers in hex. | |
172 | ||
173 | - vbe_version | |
174 | A BCD value indicating the implemented VBE standard. | |
175 | ||
176 | 5. Miscellaneous | |
177 | ---------------- | |
178 | ||
179 | Uvesafb will set a video mode with the default refresh rate and timings | |
180 | from the Video BIOS if you set pixclock to 0 in fb_var_screeninfo. | |
181 | ||
182 | ||
183 | -- | |
184 | Michal Januszewski <spock@gentoo.org> | |
185 | Last updated: 2007-06-16 | |
186 | ||
187 | Documentation of the uvesafb options is loosely based on vesafb.txt. | |
188 |