Dual-graphics switching in linux

Switch Thinkpad r400 t400 with dual-graphics card in linux, generally, ati3470 and intel4500 use the lspci | grep VGA command to see which linux cards can be used currently. By default, both of them are enabled, and the power management is very poor, as a result, the computer temperature is very high. If you forcibly switch to a video card in the BIOS, this problem can also be solved, but in the case of dual systems, it is extremely inconvenient. If you need to switch the graphics card and restart the computer, it is too far behind. Linux kernel 2.6.38 and later versions start to support dual-Card Switching. The module for switching the video card under linux3.06 is still in the debug state. First, load these modules Step 1: mount-t debugfs/sys/kernel/debug. Note: run Step 2:> cat/sys/kernel/debug/vgaswitcheroo/switch with the root permission to check whether the video card can be switched. The normal output is similar to: 0: DIS: Pwr: 0000: 01: 00.0 1: IGD: +: Pwr: 0000: 00: 02.0 if there is no output, sorry. This method is useless, it may be that the Linux kernel is outdated Step 3: echo DDIS>/sys/kernel/debug/vgaswitcheroo/switch is used to switch to the independent graphics card echo DIGD>/sys/kernel/debug/vgaswitcheroo/switch is used to switch to the integrated graphics card ech O OFF>/sys/kernel/debug/vgaswitcheroo/switch this command is used to turn OFF unused graphics card power echo ON>/sys/kernel/debug/vgaswitcheroo/switch this command is used to re-enable the power of the disabled video card is usually, run the third command echo OFF>/sys/kernel/debug/vgaswitcheroo/switch to check the status of the file/sys/kernel/debug/vgaswitcheroo/switch cat/sys/ kernel/debug/vgaswitcheroo/switch if the output result is 0: DIS: Off: 0000: 01: 00.0 1: IGD: +: Pwr: 0000: 00: 02.0. Here, "Off" indicates that the power supply has been disabled, and "Pwr" indicates that the power supply is running. At this point, you can go to rc. add mount-t debugfs/sys/kernel/debug echo OFF>/sys/kernel/debug/vgaswitcheroo/switch to the local file, in this way, the unused video card is automatically powered off every time the computer is started up, And the barbecue temperature is no longer needed.