vasilito
f31522130f
Build system (5 gaps hardened): - COOKBOOK_OFFLINE defaults to true (fork-mode) - normalize_patch handles diff -ruN format - New 'repo validate-patches' command (25/25 relibc patches) - 14 patched Qt/Wayland/display recipes added to protected list - relibc archive regenerated with current patch chain Boot fixes (fixable): - Full ISO EFI partition: 16 MiB → 1 MiB (matches mini, BIOS hardcoded 2 MiB offset) - D-Bus system bus: absolute /usr/bin/dbus-daemon path (was skipped) - redbear-sessiond: absolute /usr/bin/redbear-sessiond path (was skipped) - daemon framework: silenced spurious INIT_NOTIFY warnings for oneshot_async services (P0-daemon-silence-init-notify.patch) - udev-shim: demoted INIT_NOTIFY warning to INFO (expected for oneshot_async) - relibc: comprehensive named semaphores (sem_open/close/unlink) replacing upstream todo!() stubs - greeterd: Wayland socket timeout 15s → 30s (compositor DRM wait) - greeter-ui: built and linked (header guard unification, sem_compat stubs removed) - mc: un-ignored in both configs, fixed glib/libiconv/pcre2 transitive deps - greeter config: removed stale keymapd dependency from display/greeter services - prefix toolchain: relibc headers synced, _RELIBC_STDLIB_H guard unified Unfixable (diagnosed, upstream): - i2c-hidd: abort on no-I2C-hardware (QEMU) — process::exit → relibc abort - kded6/greeter-ui: page fault 0x8 — Qt library null deref - Thread panics fd != -1 — Rust std library on Redox - DHCP timeout / eth0 MAC — QEMU user-mode networking - hwrngd/thermald — no hardware RNG/thermal in VM - live preload allocation — BIOS memory fragmentation, continues on demand
106 lines
4.0 KiB
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106 lines
4.0 KiB
ReStructuredText
.. _touchpad_jitter:
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==============================================================================
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Touchpad jitter
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==============================================================================
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Touchpad jitter describes random movement by a few pixels even when the
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user's finger is unmoving.
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libinput has a mechanism called a **hysteresis** to avoid that jitter. When
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active, movement with in the **hysteresis margin** is discarded. If the
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movement delta is larger than the margin, the movement is passed on as
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pointer movement. This is a simplified summary, developers should
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read the implementation of the hysteresis in ``src/evdev.c``.
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libinput uses the kernel ``fuzz`` value to determine the size of the
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hysteresis. Users should override this with a udev hwdb entry where the
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device itself does not provide the correct value.
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.. _touchpad_jitter_fuzz_override:
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------------------------------------------------------------------------------
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Overriding the hysteresis margins
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------------------------------------------------------------------------------
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libinput provides the debugging tool ``libinput measure fuzz`` to help edit or
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test a fuzz value. This tool is interactive and provides a udev hwdb entry
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that matches the device. To check if a fuzz is currently present, simply run
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without arguments or with the touchpad's device node:
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::
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$ sudo libinput measure fuzz
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Using Synaptics TM2668-002: /dev/input/event17
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Checking udev property... not set
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Checking axes... x=16 y=16
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In the above output, the axis fuzz is set to 16. To set a specific fuzz, run
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with the ``--fuzz=<value>`` argument.
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::
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$ sudo libinput measure fuzz --fuzz=8
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The tool will attempt to construct a hwdb file that matches your touchpad
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device. Follow the printed prompts.
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In the ideal case, the tool will provide you with a file that can be
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submitted to the systemd repo for inclusion.
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However, hwdb entry creation is difficult to automate and it's likely
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that the tools fails in doing so, especially if an existing entry is already
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present.
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Below is the outline of what a user needs to do to override a device's fuzz
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value in case the ``libinput measure fuzz`` tool fails.
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Check with ``udevadm info /sys/class/input/eventX`` (replace your device node
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number) whether an existing hwdb override exists. If the ``EVDEV_ABS_``
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properties are present, the hwdb override exists. Find the file that
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contains that entry, most likely in ``/etc/udev/hwdb.d`` or
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``/usr/lib/udev/hwdb.d``.
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The content of the property is a set of values in the format
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``EVDEV_ABS_00=min:max:resolution:fuzz``. You need to set the ``fuzz`` part,
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leaving the remainder of the property as-is. Values may be empty, e.g. a
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property that only sets resolution and fuzz reads as ``EVDEV_ABS_00=::32:8``.
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If no properties exist, your hwdb.entry should look approximately like this:
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::
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evdev:name:Synaptics TM2668-002:dmi:*:svnLENOVO*:pvrThinkPadT440s*:
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EVDEV_ABS_00=:::8
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EVDEV_ABS_01=:::8
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EVDEV_ABS_35=:::8
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EVDEV_ABS_36=:::8
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Substitute the ``name`` field with the device name (see the output of
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``libinput measure fuzz`` and the DMI match content with your hardware. See
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:ref:`hwdb_modifying` for details.
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Once the hwdb entry has been modified, added, or created,
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:ref:`reload the hwdb <hwdb_reloading>`. Once reloaded, :ref:`libinput-record`
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"libinput record" should show the new fuzz value for the axes.
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Restart the host and libinput should pick up the revised fuzz values.
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.. _kernel_fuzz:
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------------------------------------------------------------------------------
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Kernel fuzz
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------------------------------------------------------------------------------
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A fuzz set on an absolute axis in the kernel causes the kernel to apply
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hysteresis-like behavior to the axis. Unfortunately, this behavior leads to
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inconsistent deltas. To avoid this, libinput sets the kernel fuzz on the
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device to 0 to disable this kernel behavior but remembers what the fuzz was
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on startup. The fuzz is stored in the ``LIBINPUT_FUZZ_XX`` udev property, on
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startup libinput will check that property as well as the axis itself.
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