Documentation / fb / uvesafb.txt
Custom Search
Based on kernel version 3.9. Page generated on 2013-05-02 23:05 EST.
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_option=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. This option is available on x86 63 only and is the default option on that architecture. 64 65 ywrap Same as ypan, but assumes your gfx board can wrap-around 66 the video memory (i.e. starts reading from top if it 67 reaches the end of video memory). Faster than ypan. 68 Available on x86 only. 69 70 redraw Scroll by redrawing the affected part of the screen, this 71 is the default on non-x86. 72 73 (If you're using uvesafb as a module, the above three options are 74 used a parameter of the scroll option, e.g. scroll=ypan.) 75 76 vgapal Use the standard VGA registers for palette changes. 77 78 pmipal Use the protected mode interface for palette changes. 79 This is the default if the protected mode interface is 80 available. Available on x86 only. 81 82 mtrr:n Setup memory type range registers for the framebuffer 83 where n: 84 0 - disabled (equivalent to nomtrr) (default) 85 1 - uncachable 86 2 - write-back 87 3 - write-combining 88 4 - write-through 89 90 If you see the following in dmesg, choose the type that matches 91 the old one. In this example, use "mtrr:2". 92 ... 93 mtrr: type mismatch for e0000000,8000000 old: write-back new: write-combining 94 ... 95 96 nomtrr Do not use memory type range registers. 97 98 vremap:n 99 Remap 'n' MiB of video RAM. If 0 or not specified, remap memory 100 according to video mode. 101 102 vtotal:n 103 If the video BIOS of your card incorrectly determines the total 104 amount of video RAM, use this option to override the BIOS (in MiB). 105 106 <mode> The mode you want to set, in the standard modedb format. Refer to 107 modedb.txt for a detailed description. When uvesafb is compiled as 108 a module, the mode string should be provided as a value of the 109 'mode_option' option. 110 111 vbemode:x 112 Force the use of VBE mode x. The mode will only be set if it's 113 found in the VBE-provided list of supported modes. 114 NOTE: The mode number 'x' should be specified in VESA mode number 115 notation, not the Linux kernel one (eg. 257 instead of 769). 116 HINT: If you use this option because normal <mode> parameter does 117 not work for you and you use a X server, you'll probably want to 118 set the 'nocrtc' option to ensure that the video mode is properly 119 restored after console <-> X switches. 120 121 nocrtc Do not use CRTC timings while setting the video mode. This option 122 has any effect only if the Video BIOS is VBE 3.0 compliant. Use it 123 if you have problems with modes set the standard way. Note that 124 using this option implies that any refresh rate adjustments will 125 be ignored and the refresh rate will stay at your BIOS default (60 Hz). 126 127 noedid Do not try to fetch and use EDID-provided modes. 128 129 noblank Disable hardware blanking. 130 131 v86d:path 132 Set path to the v86d executable. This option is only available as 133 a module parameter, and not as a part of the video= string. If you 134 need to use it and have uvesafb built into the kernel, use 135 uvesafb.v86d="path". 136 137 Additionally, the following parameters may be provided. They all override the 138 EDID-provided values and BIOS defaults. Refer to your monitor's specs to get 139 the correct values for maxhf, maxvf and maxclk for your hardware. 140 141 maxhf:n Maximum horizontal frequency (in kHz). 142 maxvf:n Maximum vertical frequency (in Hz). 143 maxclk:n Maximum pixel clock (in MHz). 144 145 4. The sysfs interface 146 ---------------------- 147 148 uvesafb provides several sysfs nodes for configurable parameters and 149 additional information. 150 151 Driver attributes: 152 153 /sys/bus/platform/drivers/uvesafb 154 - v86d (default: /sbin/v86d) 155 Path to the v86d executable. v86d is started by uvesafb 156 if an instance of the daemon isn't already running. 157 158 Device attributes: 159 160 /sys/bus/platform/drivers/uvesafb/uvesafb.0 161 - nocrtc 162 Use the default refresh rate (60 Hz) if set to 1. 163 164 - oem_product_name 165 - oem_product_rev 166 - oem_string 167 - oem_vendor 168 Information about the card and its maker. 169 170 - vbe_modes 171 A list of video modes supported by the Video BIOS along with their 172 VBE mode numbers in hex. 173 174 - vbe_version 175 A BCD value indicating the implemented VBE standard. 176 177 5. Miscellaneous 178 ---------------- 179 180 Uvesafb will set a video mode with the default refresh rate and timings 181 from the Video BIOS if you set pixclock to 0 in fb_var_screeninfo. 182 183 184 -- 185 Michal Januszewski <spock@gentoo.org> 186 Last updated: 2009-03-30 187 188 Documentation of the uvesafb options is loosely based on vesafb.txt.
- [ fb ]
- 00-INDEX
- api.txt
- arkfb.txt
- aty128fb.txt
- cirrusfb.txt
- cmap_xfbdev.txt
- deferred_io.txt
- efifb.txt
- ep93xx-fb.txt
- fbcon.txt
- framebuffer.txt
- gxfb.txt
- intel810.txt
- intelfb.txt
- internals.txt
- lxfb.txt
- matroxfb.txt
- metronomefb.txt
- modedb.txt
- pvr2fb.txt
- pxafb.txt
- s3fb.txt
- sa1100fb.txt
- sh7760fb.txt
- sisfb.txt
- sm501.txt
- sstfb.txt
- tgafb.txt
- tridentfb.txt
- udlfb.txt
- uvesafb.txt
- vesafb.txt
- viafb.modes
- viafb.txt
- vt8623fb.txt
Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.