103 lines
3.1 KiB
Plaintext
103 lines
3.1 KiB
Plaintext
# HID-BPF programs
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This directory contains various fixes for devices. They add new features or
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fix some behaviors without being entirely mandatory. It is better to load them
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when you have such a device, but they should not be a requirement for a device
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to be working during the boot stage.
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The .bpf.c files provided here are not automatically compiled in the kernel.
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They should be loaded in the kernel by `udev-hid-bpf`:
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https://gitlab.freedesktop.org/libevdev/udev-hid-bpf
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The main reasons for these fixes to be here is to have a central place to
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"upstream" them, but also this way we can test them thanks to the HID
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selftests.
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Once a .bpf.c file is accepted here, it is duplicated in `udev-hid-bpf`
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in the `src/bpf/stable` directory, and distributions are encouraged to
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only ship those bpf objects. So adding a file here should eventually
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land in distributions when they update `udev-hid-bpf`
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## Compilation
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Just run `make`
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## Installation
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### Automated way
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Just run `sudo udev-hid-bpf install ./my-awesome-fix.bpf.o`
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### Manual way
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- copy the `.bpf.o` you want in `/etc/udev-hid-bpf/`
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- create a new udev rule to automatically load it
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The following should do the trick (assuming udev-hid-bpf is available in
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/usr/bin):
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```
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$> cp xppen-ArtistPro16Gen2.bpf.o /etc/udev-hid-bpf/
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$> udev-hid-bpf inspect xppen-ArtistPro16Gen2.bpf.o
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[
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{
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"name": "xppen-ArtistPro16Gen2.bpf.o",
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"devices": [
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{
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"bus": "0x0003",
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"group": "0x0001",
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"vid": "0x28BD",
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"pid": "0x095A"
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},
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{
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"bus": "0x0003",
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"group": "0x0001",
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"vid": "0x28BD",
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"pid": "0x095B"
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}
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],
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...
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$> cat <EOF > /etc/udev/rules.d/99-load-hid-bpf-xppen-ArtistPro16Gen2.rules
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ACTION!="add|remove", GOTO="hid_bpf_end"
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SUBSYSTEM!="hid", GOTO="hid_bpf_end"
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# xppen-ArtistPro16Gen2.bpf.o
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ACTION=="add",ENV{MODALIAS}=="hid:b0003g0001v000028BDp0000095A", RUN{program}+="/usr/local/bin/udev-hid-bpf add $sys$devpath /etc/udev-hid-bpf/xppen-ArtistPro16Gen2.bpf.o"
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ACTION=="remove",ENV{MODALIAS}=="hid:b0003g0001v000028BDp0000095A", RUN{program}+="/usr/local/bin/udev-hid-bpf remove $sys$devpath "
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# xppen-ArtistPro16Gen2.bpf.o
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ACTION=="add",ENV{MODALIAS}=="hid:b0003g0001v000028BDp0000095B", RUN{program}+="/usr/local/bin/udev-hid-bpf add $sys$devpath /etc/udev-hid-bpf/xppen-ArtistPro16Gen2.bpf.o"
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ACTION=="remove",ENV{MODALIAS}=="hid:b0003g0001v000028BDp0000095B", RUN{program}+="/usr/local/bin/udev-hid-bpf remove $sys$devpath "
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LABEL="hid_bpf_end"
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EOF
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$> udevadm control --reload
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```
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Then unplug and replug the device.
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## Checks
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### udev rule
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You can check that the udev rule is correctly working by issuing
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```
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$> udevadm test /sys/bus/hid/devices/0003:28BD:095B*
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...
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run: '/usr/local/bin/udev-hid-bpf add /sys/devices/virtual/misc/uhid/0003:28BD:095B.0E57 /etc/udev-hid-bpf/xppen-ArtistPro16Gen2.bpf.o'
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```
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### program loaded
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You can check that the program has been properly loaded with `bpftool`
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```
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$> bpftool prog
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...
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247: tracing name xppen_16_fix_eraser tag 18d389353ed2ef07 gpl
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loaded_at 2024-03-28T16:02:28+0100 uid 0
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xlated 120B jited 77B memlock 4096B
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btf_id 487
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```
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