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174 lines
6.4 KiB
Markdown
174 lines
6.4 KiB
Markdown
*Migrated from https://github.com/Lekensteyn/acpi-stuff*
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About
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-----
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bbswitch is a kernel module which automatically detects the required ACPI calls
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for two kinds of Optimus laptops. It has been verified to work with "real"
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Optimus and "legacy" Optimus laptops (at least, that is how I call them). The
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machines on which these tests has performed are:
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- Clevo B7130 - GT 425M ("real" Optimus, Lekensteyns laptop)
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- Dell Vostro 3500 - GT 310M ("legacy" Optimus, Samsagax' laptop)
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(note: there is no need to add more supported laptops here as the universal
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calls should work for every laptop model supporting either Optimus calls)
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It's preferred over manually hacking with the acpi_call module because it can
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detect the correct handle preceding _DSM and has some built-in safeguards:
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- You're not allowed to disable a card if a driver (nouveau, nvidia) is loaded.
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- Before suspend, the card is automatically enabled. When resuming, it's
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disabled again if that was the case before suspending. Hibernation should
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work, but it not tested.
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Precautionary measure :
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- On some machines, turning off the card is permanent and the card does not
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reappear on subsequents reboots, which can result into the screen staying
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black all the time, including the BIOS screen.
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If it occurs, first try to shutdown, unplug power cord, remove battery, wait
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30s, then put everything back in and boot. If it's not solved, then the
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solution is to reset the BIOS to factory settings. Before executing bbswitch
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for the first time, it is therefore recommended to take note of the full key
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sequence in the BIOS to do a reset.
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Build
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-----
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Build the module (kernel headers are required):
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make
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Then load it (requires root privileges, i.e. `sudo`):
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make load
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If your card is supported, there should be no error. Otherwise, you get a "No
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such device" (ENODEV) error. Check your kernel log (dmesg) for more
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information.
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DKMS support
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------------
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If you have DKMS installed, you can install bbswitch in such a way that it
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survives kernel upgrades. It is recommended to remove older versions of bbswitch
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by running `dkms remove -m bbswitch -v OLDVERSION --all` as root. To install
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the new version, simply run:
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# make -f Makefile.dkms
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To uninstall it, run:
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# make -f Makefile.dkms uninstall
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Usage
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-----
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bbswitch has three commands to check the card status and switching
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(`#` means "run with root privileges, i.e. run it prefixed with `sudo `):
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### Get the status:
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# cat /proc/acpi/bbswitch
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0000:01:00.0 ON
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### Turn the card off, respectively on:
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# tee /proc/acpi/bbswitch <<<OFF
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# tee /proc/acpi/bbswitch <<<ON
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If the card stays on when trying to disable it, you've probably forgotten to
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unload the driver,
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$ dmesg |tail -1
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bbswitch: device 0000:01:00.0 is in use by driver 'nouveau', refusing OFF
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Do **not** attempt to load a driver while the card is off or the card won't be
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usable until the PCI configuration space has been recovered (for example, after
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writing the contents manually or rebooting).
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### Module options
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The module has some options that control the behavior on loading and unloading:
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`load_state` and `unload_state`. Valid values are `-1`, `0` and `1` meaning "do
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not change the card state", "turn the card off" and "turn the card on"
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respectively. For example, if you want to have `bbswitch` disable the card
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immediately when loading the module while enabling the card on unload, load the
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module with:
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# modprobe bbswitch load_state=0 unload_state=1
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The `unload_state` value can be changed on runtime, the above command yields the
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same behavior as:
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# modprobe bbswitch load_state=0
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# echo 1 | tee /sys/module/bbswitch/parameters/unload_state
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If not explictly set, the default behavior is not to change the power state of
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the discrete video card which equals to `load_state=-1 unload_state=-1`.
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The Lenovo T410 and Lenovo T410s laptops need the module option
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`skip_optimus_dsm=1`, otherwise it will detect the wrong methods which result in
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the card not being disabled.
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### Disable card on boot
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These options can be useful to disable the card on boot time. Depending on your
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distribution, `/etc/modules`, `/etc/modules.conf` or some other file can be used
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to load modules on boot time. Adding the below line to the file makes the card
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get disabled on boot:
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bbswitch load_state=0
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Users of `kmod` should create `/etc/modprobe.d/bbswitch.conf` containing
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`options bbswitch load_state=0` to set the default options. To load the module,
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systemd users should create `/etc/modules-load.d/bbswitch.conf` containing
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`bbswitch`.
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You have to update your initial ramdisk (initrd) for the changes propagate to
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the boot process. On Debian and Ubuntu, this can performed by running
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`update-initramfs -u` as root.
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### Enable card on shutdown
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Some machines do not like the card being disabled at shutdown.
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Add the next initscript (`/etc/init/bbswitch.conf`) :
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description "Save power by disabling nvidia on Optimus"
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author "Lekensteyn <lekensteyn@gmail.com>"
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start on runlevel [2345]
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stop on runlevel [016]
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pre-start exec /sbin/modprobe bbswitch load_state=0 unload_state=1
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pre-stop exec /sbin/rmmod bbswitch
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Reporting bugs
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--------------
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This module has been integrated in Bumblebee "Tumbleweed". Please report any
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issues on this module in the issue tracker and provide the following details:
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- The output of `dmesg | grep -C 10 bbswitch:`
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- The kernel version `uname -a`
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- Your distribution and version (if applicable)
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- The version of your Xorg and the driver
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- Submit your machine information on https://bugs.launchpad.net/bugs/752542;
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the instructions are listed in the bug description. Summary: install the
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packages containing `dmidecode`, `acpidump` and `iasl` and then run:
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wget http://lekensteyn.nl/files/get-acpi-info.sh
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sh get-acpi-info.sh
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- Information about the ACPI handles associated with PCI devices. Since this is
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a kernel module, you'll need kernel headers, gcc and automake. Commands:
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git clone git://github.com/Lekensteyn/acpi-stuff.git --depth 1
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cd acpi-stuff/acpi_dump_info
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make
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sudo make load
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cat /proc/acpi/dump_info
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Upload the generated tarball on the above Launchpad URL and provide a link to
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the comment containing your report.
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TODO
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----
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With the new PCI device approach, if load_state=0, then starting bumblebeed will
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unload bbswitch. Fix Bumblebee not to unload the module when the PM method is
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bbswitch and the loaded module is bbswitch.
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