1 ==============================================
2 uvesafb - A Generic Driver for VBE2+ compliant
3 ==============================================
4
5 1. Requirements
6 ---------------
7
8 uvesafb should work with any video card that h
9 with the VBE 2.0 standard.
10
11 Unlike other drivers, uvesafb makes use of a u
12 v86d. v86d is used to run the x86 Video BIOS
13 controlled environment. This allows uvesafb t
14 than x86. Check the v86d documentation for a
15 arches.
16
17 v86d source code can be downloaded from the fo
18
19 https://github.com/mjanusz/v86d
20
21 Please refer to the v86d documentation for det
22 installation instructions.
23
24 Note that the v86d userspace helper has to be
25 order for uvesafb to work properly. If you wa
26 early boot, you will have to include v86d into
27 either compile it into the kernel or use it as
28
29 2. Caveats and limitations
30 --------------------------
31
32 uvesafb is a _generic_ driver which supports a
33 cards, but which is ultimately limited by the
34 The most important limitations are:
35
36 - Lack of any type of acceleration.
37 - A strict and limited set of supported video
38 or most optimal resolution/refresh rate for
39 with uvesafb, simply because the Video BIOS
40 video mode you want to use. This can be esp
41 widescreen panels, where native video modes
42 ratio, which is what most BIOS-es are limite
43 - Adjusting the refresh rate is only possible
44 Video BIOS. Note that many nVidia Video BIO
45 compliant, while they simply ignore any refr
46
47 3. Configuration
48 ----------------
49
50 uvesafb can be compiled either as a module, or
51 In both cases it supports the same set of conf
52 are either given on the kernel command line or
53
54 video=uvesafb:1024x768-32,mtrr:3,ywrap (compi
55
56 # modprobe uvesafb mode_option=1024x768-32 mt
57
58 Accepted options:
59
60 ======= ======================================
61 ypan Enable display panning using the VESA
62 interface. The visible screen is just
63 video memory, console scrolling is don
64 start of the window. This option is a
65 only and is the default option on that
66
67 ywrap Same as ypan, but assumes your gfx boa
68 the video memory (i.e. starts reading
69 reaches the end of video memory). Fas
70 Available on x86 only.
71
72 redraw Scroll by redrawing the affected part
73 is the default on non-x86.
74 ======= ======================================
75
76 (If you're using uvesafb as a module, the abov
77 used a parameter of the scroll option, e.g. sc
78
79 =========== ==================================
80 vgapal Use the standard VGA registers for
81
82 pmipal Use the protected mode interface f
83 This is the default if the protect
84 available. Available on x86 only.
85
86 mtrr:n Setup memory type range registers
87 where n:
88
89 - 0 - disabled (equivalent to
90 - 3 - write-combining (default
91
92 Values other than 0 and 3 will res
93 treated just like 3.
94
95 nomtrr Do not use memory type range regis
96
97 vremap:n
98 Remap 'n' MiB of video RAM. If 0
99 according to video mode.
100
101 vtotal:n If the video BIOS of your card inc
102 amount of video RAM, use this opti
103
104 <mode> The mode you want to set, in the s
105 modedb.txt for a detailed descript
106 a module, the mode string should b
107 'mode_option' option.
108
109 vbemode:x Force the use of VBE mode x. The
110 found in the VBE-provided list of
111 NOTE: The mode number 'x' should b
112 notation, not the Linux kernel one
113 HINT: If you use this option becau
114 not work for you and you use a X s
115 set the 'nocrtc' option to ensure
116 restored after console <-> X switc
117
118 nocrtc Do not use CRTC timings while sett
119 has any effect only if the Video B
120 if you have problems with modes se
121 using this option implies that any
122 be ignored and the refresh rate wi
123 (60 Hz).
124
125 noedid Do not try to fetch and use EDID-p
126
127 noblank Disable hardware blanking.
128
129 v86d:path Set path to the v86d executable. T
130 a module parameter, and not as a p
131 need to use it and have uvesafb bu
132 uvesafb.v86d="path".
133 =========== ==================================
134
135 Additionally, the following parameters may be
136 EDID-provided values and BIOS defaults. Refer
137 the correct values for maxhf, maxvf and maxclk
138
139 =========== ==================================
140 maxhf:n Maximum horizontal frequency (in k
141 maxvf:n Maximum vertical frequency (in Hz)
142 maxclk:n Maximum pixel clock (in MHz).
143 =========== ==================================
144
145 4. The sysfs interface
146 ----------------------
147
148 uvesafb provides several sysfs nodes for confi
149 additional information.
150
151 Driver attributes:
152
153 /sys/bus/platform/drivers/uvesafb
154 v86d
155 (default: /sbin/v86d)
156
157 Path to the v86d executable. v86d is start
158 if an instance of the daemon isn't already
159
160 Device attributes:
161
162 /sys/bus/platform/drivers/uvesafb/uvesafb.0
163 nocrtc
164 Use the default refresh rate (60 Hz) if se
165
166 oem_product_name, oem_product_rev, oem_strin
167 Information about the card and its maker.
168
169 vbe_modes
170 A list of video modes supported by the Vid
171 VBE mode numbers in hex.
172
173 vbe_version
174 A BCD value indicating the implemented VBE
175
176 5. Miscellaneous
177 ----------------
178
179 Uvesafb will set a video mode with the default
180 from the Video BIOS if you set pixclock to 0 i
181
182
183
184 Michal Januszewski <spock@gentoo.org>
185
186 Last updated: 2017-10-10
187
188 Documentation of the uvesafb options is loose
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