It can mute (completely or partly) sound on IBM/Lenovo ThinkPad laptops,
and you would not be able to unmute it with OSS Mixer, or any other OSS4 tools.
acpid trojan is a "low level tool" https://wiki.archlinux.org/index.php/Ex ... board_Keys
It is a kind of rootkit deeply rooted into the Linux kernel.
On Linux Mint 13 and 14, acpid trojan is installed by default.
How to detect acpid trojan:
Code: Select all
$ ps -ef | grep acpi
root 1052 1 0 19:02 ? 00:00:00 acpid -c /etc/acpi/events -s /var/run/acpid.socket
root 1199 2 0 19:02 ? 00:00:00 [ktpacpid]
root 1200 2 0 19:02 ? 00:00:03 [ktpacpi_nvramd]
igor 9726 9623 0 21:56 pts/2 00:00:00 acpi_listen
igor 11036 10219 0 22:27 pts/1 00:00:00 grep --colour=auto acpi
On my IBM ThinkPad, there are three special multimedia keys:
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ibm/hotkey HKEY 00000080 00001015 [Volume up]
ibm/hotkey HKEY 00000080 00001016 [Volume down]
ibm/hotkey HKEY 00000080 00001017 [Volume mute]
These special multimedia keys are located near the "Access IBM" button.
If OSS4 sound is muted by acpid trojan, you can unmute it with special multimedia keys, provided that those keys work.
However, such keys usually do not work on Linux. You should fix them yourself, if you know how to do this
https://wiki.archlinux.org/index.php/Ex ... board_Keys
If OSS4 sound is muted (or semi-muted) by acpid trojan, and special multimedia keys do not work (this is usually the case), you would not be able to unmute it.
The OSS4 users may also experience other problems with IBM/Lenovo ThinkPad laptops, for example: viewtopic.php?f=3&t=5204
IBM/Lenovo ThinkPad hotkeys (multimedia keys) were disabled in Linux in 2009.
They can be enabled with a special secret command:
http://forums.linuxmint.com/viewtopic.p ... 88#p154863
https://wiki.archlinux.org/index.php/IB ... nd_Buttons
When the hotkeys (multimedia keys) are enabled, the pop-up notifications work as they should with MATE Desktop,
- mate-settings-daemon-gstreamer (default): uses gstreamer to provide media keys.
- mate-settings-daemon-pulse: uses pulseaudio to provide media keys.
http://forums.mate-desktop.org/viewtopi ... &t=38#p123