1 ============================================== 1 ==========================================================
2 uvesafb - A Generic Driver for VBE2+ compliant 2 uvesafb - A Generic Driver for VBE2+ compliant video cards
3 ============================================== 3 ==========================================================
4 4
5 1. Requirements 5 1. Requirements
6 --------------- 6 ---------------
7 7
8 uvesafb should work with any video card that h 8 uvesafb should work with any video card that has a Video BIOS compliant
9 with the VBE 2.0 standard. 9 with the VBE 2.0 standard.
10 10
11 Unlike other drivers, uvesafb makes use of a u 11 Unlike other drivers, uvesafb makes use of a userspace helper called
12 v86d. v86d is used to run the x86 Video BIOS 12 v86d. v86d is used to run the x86 Video BIOS code in a simulated and
13 controlled environment. This allows uvesafb t 13 controlled environment. This allows uvesafb to function on arches other
14 than x86. Check the v86d documentation for a 14 than x86. Check the v86d documentation for a list of currently supported
15 arches. 15 arches.
16 16
17 v86d source code can be downloaded from the fo 17 v86d source code can be downloaded from the following website:
18 18
19 https://github.com/mjanusz/v86d 19 https://github.com/mjanusz/v86d
20 20
21 Please refer to the v86d documentation for det 21 Please refer to the v86d documentation for detailed configuration and
22 installation instructions. 22 installation instructions.
23 23
24 Note that the v86d userspace helper has to be 24 Note that the v86d userspace helper has to be available at all times in
25 order for uvesafb to work properly. If you wa 25 order for uvesafb to work properly. If you want to use uvesafb during
26 early boot, you will have to include v86d into 26 early boot, you will have to include v86d into an initramfs image, and
27 either compile it into the kernel or use it as 27 either compile it into the kernel or use it as an initrd.
28 28
29 2. Caveats and limitations 29 2. Caveats and limitations
30 -------------------------- 30 --------------------------
31 31
32 uvesafb is a _generic_ driver which supports a 32 uvesafb is a _generic_ driver which supports a wide variety of video
33 cards, but which is ultimately limited by the 33 cards, but which is ultimately limited by the Video BIOS interface.
34 The most important limitations are: 34 The most important limitations are:
35 35
36 - Lack of any type of acceleration. 36 - Lack of any type of acceleration.
37 - A strict and limited set of supported video 37 - A strict and limited set of supported video modes. Often the native
38 or most optimal resolution/refresh rate for 38 or most optimal resolution/refresh rate for your setup will not work
39 with uvesafb, simply because the Video BIOS 39 with uvesafb, simply because the Video BIOS doesn't support the
40 video mode you want to use. This can be esp 40 video mode you want to use. This can be especially painful with
41 widescreen panels, where native video modes 41 widescreen panels, where native video modes don't have the 4:3 aspect
42 ratio, which is what most BIOS-es are limite 42 ratio, which is what most BIOS-es are limited to.
43 - Adjusting the refresh rate is only possible 43 - Adjusting the refresh rate is only possible with a VBE 3.0 compliant
44 Video BIOS. Note that many nVidia Video BIO 44 Video BIOS. Note that many nVidia Video BIOS-es claim to be VBE 3.0
45 compliant, while they simply ignore any refr 45 compliant, while they simply ignore any refresh rate settings.
46 46
47 3. Configuration 47 3. Configuration
48 ---------------- 48 ----------------
49 49
50 uvesafb can be compiled either as a module, or 50 uvesafb can be compiled either as a module, or directly into the kernel.
51 In both cases it supports the same set of conf 51 In both cases it supports the same set of configuration options, which
52 are either given on the kernel command line or 52 are either given on the kernel command line or as module parameters, e.g.::
53 53
54 video=uvesafb:1024x768-32,mtrr:3,ywrap (compi 54 video=uvesafb:1024x768-32,mtrr:3,ywrap (compiled into the kernel)
55 55
56 # modprobe uvesafb mode_option=1024x768-32 mt 56 # modprobe uvesafb mode_option=1024x768-32 mtrr=3 scroll=ywrap (module)
57 57
58 Accepted options: 58 Accepted options:
59 59
60 ======= ====================================== 60 ======= =========================================================
61 ypan Enable display panning using the VESA 61 ypan Enable display panning using the VESA protected mode
62 interface. The visible screen is just 62 interface. The visible screen is just a window of the
63 video memory, console scrolling is don 63 video memory, console scrolling is done by changing the
64 start of the window. This option is a 64 start of the window. This option is available on x86
65 only and is the default option on that 65 only and is the default option on that architecture.
66 66
67 ywrap Same as ypan, but assumes your gfx boa 67 ywrap Same as ypan, but assumes your gfx board can wrap-around
68 the video memory (i.e. starts reading 68 the video memory (i.e. starts reading from top if it
69 reaches the end of video memory). Fas 69 reaches the end of video memory). Faster than ypan.
70 Available on x86 only. 70 Available on x86 only.
71 71
72 redraw Scroll by redrawing the affected part 72 redraw Scroll by redrawing the affected part of the screen, this
73 is the default on non-x86. 73 is the default on non-x86.
74 ======= ====================================== 74 ======= =========================================================
75 75
76 (If you're using uvesafb as a module, the abov 76 (If you're using uvesafb as a module, the above three options are
77 used a parameter of the scroll option, e.g. sc 77 used a parameter of the scroll option, e.g. scroll=ypan.)
78 78
79 =========== ================================== 79 =========== ====================================================================
80 vgapal Use the standard VGA registers for 80 vgapal Use the standard VGA registers for palette changes.
81 81
82 pmipal Use the protected mode interface f 82 pmipal Use the protected mode interface for palette changes.
83 This is the default if the protect 83 This is the default if the protected mode interface is
84 available. Available on x86 only. 84 available. Available on x86 only.
85 85
86 mtrr:n Setup memory type range registers 86 mtrr:n Setup memory type range registers for the framebuffer
87 where n: 87 where n:
88 88
89 - 0 - disabled (equivalent to 89 - 0 - disabled (equivalent to nomtrr)
90 - 3 - write-combining (default 90 - 3 - write-combining (default)
91 91
92 Values other than 0 and 3 will res 92 Values other than 0 and 3 will result in a warning and will be
93 treated just like 3. 93 treated just like 3.
94 94
95 nomtrr Do not use memory type range regis 95 nomtrr Do not use memory type range registers.
96 96
97 vremap:n 97 vremap:n
98 Remap 'n' MiB of video RAM. If 0 98 Remap 'n' MiB of video RAM. If 0 or not specified, remap memory
99 according to video mode. 99 according to video mode.
100 100
101 vtotal:n If the video BIOS of your card inc 101 vtotal:n If the video BIOS of your card incorrectly determines the total
102 amount of video RAM, use this opti 102 amount of video RAM, use this option to override the BIOS (in MiB).
103 103
104 <mode> The mode you want to set, in the s 104 <mode> The mode you want to set, in the standard modedb format. Refer to
105 modedb.txt for a detailed descript 105 modedb.txt for a detailed description. When uvesafb is compiled as
106 a module, the mode string should b 106 a module, the mode string should be provided as a value of the
107 'mode_option' option. 107 'mode_option' option.
108 108
109 vbemode:x Force the use of VBE mode x. The 109 vbemode:x Force the use of VBE mode x. The mode will only be set if it's
110 found in the VBE-provided list of 110 found in the VBE-provided list of supported modes.
111 NOTE: The mode number 'x' should b 111 NOTE: The mode number 'x' should be specified in VESA mode number
112 notation, not the Linux kernel one 112 notation, not the Linux kernel one (eg. 257 instead of 769).
113 HINT: If you use this option becau 113 HINT: If you use this option because normal <mode> parameter does
114 not work for you and you use a X s 114 not work for you and you use a X server, you'll probably want to
115 set the 'nocrtc' option to ensure 115 set the 'nocrtc' option to ensure that the video mode is properly
116 restored after console <-> X switc 116 restored after console <-> X switches.
117 117
118 nocrtc Do not use CRTC timings while sett 118 nocrtc Do not use CRTC timings while setting the video mode. This option
119 has any effect only if the Video B 119 has any effect only if the Video BIOS is VBE 3.0 compliant. Use it
120 if you have problems with modes se 120 if you have problems with modes set the standard way. Note that
121 using this option implies that any 121 using this option implies that any refresh rate adjustments will
122 be ignored and the refresh rate wi 122 be ignored and the refresh rate will stay at your BIOS default
123 (60 Hz). 123 (60 Hz).
124 124
125 noedid Do not try to fetch and use EDID-p 125 noedid Do not try to fetch and use EDID-provided modes.
126 126
127 noblank Disable hardware blanking. 127 noblank Disable hardware blanking.
128 128
129 v86d:path Set path to the v86d executable. T 129 v86d:path Set path to the v86d executable. This option is only available as
130 a module parameter, and not as a p 130 a module parameter, and not as a part of the video= string. If you
131 need to use it and have uvesafb bu 131 need to use it and have uvesafb built into the kernel, use
132 uvesafb.v86d="path". 132 uvesafb.v86d="path".
133 =========== ================================== 133 =========== ====================================================================
134 134
135 Additionally, the following parameters may be 135 Additionally, the following parameters may be provided. They all override the
136 EDID-provided values and BIOS defaults. Refer 136 EDID-provided values and BIOS defaults. Refer to your monitor's specs to get
137 the correct values for maxhf, maxvf and maxclk 137 the correct values for maxhf, maxvf and maxclk for your hardware.
138 138
139 =========== ================================== 139 =========== ======================================
140 maxhf:n Maximum horizontal frequency (in k 140 maxhf:n Maximum horizontal frequency (in kHz).
141 maxvf:n Maximum vertical frequency (in Hz) 141 maxvf:n Maximum vertical frequency (in Hz).
142 maxclk:n Maximum pixel clock (in MHz). 142 maxclk:n Maximum pixel clock (in MHz).
143 =========== ================================== 143 =========== ======================================
144 144
145 4. The sysfs interface 145 4. The sysfs interface
146 ---------------------- 146 ----------------------
147 147
148 uvesafb provides several sysfs nodes for confi 148 uvesafb provides several sysfs nodes for configurable parameters and
149 additional information. 149 additional information.
150 150
151 Driver attributes: 151 Driver attributes:
152 152
153 /sys/bus/platform/drivers/uvesafb 153 /sys/bus/platform/drivers/uvesafb
154 v86d 154 v86d
155 (default: /sbin/v86d) 155 (default: /sbin/v86d)
156 156
157 Path to the v86d executable. v86d is start 157 Path to the v86d executable. v86d is started by uvesafb
158 if an instance of the daemon isn't already 158 if an instance of the daemon isn't already running.
159 159
160 Device attributes: 160 Device attributes:
161 161
162 /sys/bus/platform/drivers/uvesafb/uvesafb.0 162 /sys/bus/platform/drivers/uvesafb/uvesafb.0
163 nocrtc 163 nocrtc
164 Use the default refresh rate (60 Hz) if se 164 Use the default refresh rate (60 Hz) if set to 1.
165 165
166 oem_product_name, oem_product_rev, oem_strin 166 oem_product_name, oem_product_rev, oem_string, oem_vendor
167 Information about the card and its maker. 167 Information about the card and its maker.
168 168
169 vbe_modes 169 vbe_modes
170 A list of video modes supported by the Vid 170 A list of video modes supported by the Video BIOS along with their
171 VBE mode numbers in hex. 171 VBE mode numbers in hex.
172 172
173 vbe_version 173 vbe_version
174 A BCD value indicating the implemented VBE 174 A BCD value indicating the implemented VBE standard.
175 175
176 5. Miscellaneous 176 5. Miscellaneous
177 ---------------- 177 ----------------
178 178
179 Uvesafb will set a video mode with the default 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 i 180 from the Video BIOS if you set pixclock to 0 in fb_var_screeninfo.
181 181
182 182
183 183
184 Michal Januszewski <spock@gentoo.org> 184 Michal Januszewski <spock@gentoo.org>
185 185
186 Last updated: 2017-10-10 186 Last updated: 2017-10-10
187 187
188 Documentation of the uvesafb options is loose 188 Documentation of the uvesafb options is loosely based on vesafb.txt.
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