| 1 | <?xml version='1.0' encoding='UTF-8'?>
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| 2 | <!DOCTYPE topic PUBLIC "-//OASIS//DTD DITA Topic//EN" "topic.dtd">
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| 3 | <topic xml:lang="en-us" id="pcspeaker_passthrough">
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| 4 | <title>PC Speaker Passthrough</title>
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| 5 |
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| 6 | <body>
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| 7 | <p>As an experimental feature, primarily due to being limited to Linux host only and unknown Linux distribution
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| 8 | coverage, <ph conkeyref="vbox-conkeyref-phrases/product-name"/> supports passing through the PC speaker to the
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| 9 | host. The PC speaker, sometimes called the system speaker, is a way to produce audible feedback such as beeps
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| 10 | without the need for regular audio and sound card support. </p>
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| 11 | <p>The PC speaker passthrough feature in <ph conkeyref="vbox-conkeyref-phrases/product-name"/> handles beeps only.
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| 12 | Advanced PC speaker use by the VM, such as PCM audio, will not work, resulting in undefined host behavior. </p>
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| 13 | <p>Producing beeps on Linux is a very complex topic. <ph conkeyref="vbox-conkeyref-phrases/product-name"/> offers a
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| 14 | collection of options, in an attempt to make this work deterministically and reliably on as many Linux
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| 15 | distributions and system configurations as possible. These are summarized in the following table. </p>
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| 16 | <table id="table-pcspeaker-config">
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| 17 | <title>PC Speaker Configuration Options</title>
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| 18 | <desc>PC Speaker Configuration Options</desc>
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| 19 | <tgroup cols="3">
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| 20 | <thead>
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| 21 | <row>
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| 22 | <entry>
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| 23 | <p>
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| 24 | <b outputclass="bold">Code</b>
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| 25 | </p>
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| 26 | </entry>
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| 27 | <entry>
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| 28 | <p>
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| 29 | <b outputclass="bold">Device</b>
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| 30 | </p>
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| 31 | </entry>
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| 32 | <entry>
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| 33 | <p>
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| 34 | <b outputclass="bold">Notes</b>
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| 35 | </p>
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| 36 | </entry>
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| 37 | </row>
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| 38 | </thead>
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| 39 | <tbody>
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| 40 | <row>
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| 41 | <entry>
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| 42 | <p>
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| 43 | 1
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| 44 | </p>
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| 45 | </entry>
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| 46 | <entry>
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| 47 | <p>
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| 48 | <filepath>/dev/input/by-path/platform-pcspkr-event-spkr</filepath>
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| 49 | </p>
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| 50 | </entry>
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| 51 | <entry>
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| 52 | <p>
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| 53 | Direct host PC speaker use.
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| 54 | </p>
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| 55 | </entry>
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| 56 | </row>
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| 57 | <row>
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| 58 | <entry>
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| 59 | <p>
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| 60 | 2
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| 61 | </p>
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| 62 | </entry>
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| 63 | <entry>
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| 64 | <filepath>/dev/tty</filepath>
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| 65 | </entry>
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| 66 | <entry>
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| 67 | <p>
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| 68 | Uses the terminal association of the VM process. VM
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| 69 | needs to be started on a virtual console.
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| 70 | </p>
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| 71 | </entry>
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| 72 | </row>
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| 73 | <row>
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| 74 | <entry>
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| 75 | <p>
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| 76 | 3
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| 77 | </p>
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| 78 | </entry>
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| 79 | <entry>
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| 80 | <p><filepath>/dev/tty0</filepath> or
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| 81 | <filepath>/dev/vc/0</filepath>
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| 82 | </p>
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| 83 | </entry>
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| 84 | <entry>
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| 85 | <p>
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| 86 | Can only be used by user <codeph>root</codeph> or
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| 87 | users with <codeph>cap_sys_tty_config</codeph>
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| 88 | capability.
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| 89 | </p>
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| 90 | </entry>
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| 91 | </row>
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| 92 | <row>
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| 93 | <entry>
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| 94 | <p>
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| 95 | 9
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| 96 | </p>
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| 97 | </entry>
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| 98 | <entry>
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| 99 | <p>
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| 100 | A user-specified console or evdev device path.
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| 101 | </p>
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| 102 | </entry>
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| 103 | <entry>
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| 104 | <p>
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| 105 | As for codes 1 to 3, but with a custom device path.
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| 106 | </p>
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| 107 | </entry>
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| 108 | </row>
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| 109 | <row>
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| 110 | <entry>
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| 111 | <p>
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| 112 | 70
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| 113 | </p>
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| 114 | </entry>
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| 115 | <entry>
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| 116 | <p>
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| 117 | <filepath>/dev/tty</filepath>
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| 118 | </p>
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| 119 | </entry>
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| 120 | <entry>
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| 121 | <p>
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| 122 | Standard beep only. Loses frequency and length. See code
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| 123 | 2.
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| 124 | </p>
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| 125 | </entry>
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| 126 | </row>
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| 127 | <row>
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| 128 | <entry>
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| 129 | <p>
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| 130 | 79
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| 131 | </p>
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| 132 | </entry>
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| 133 | <entry>
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| 134 | <p>
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| 135 | A user-specified terminal device path.
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| 136 | </p>
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| 137 | </entry>
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| 138 | <entry>
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| 139 | <p>
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| 140 | As for code 70, but with a custom device path.
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| 141 | </p>
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| 142 | </entry>
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| 143 | </row>
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| 144 | <row>
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| 145 | <entry>
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| 146 | <p>
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| 147 | 100
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| 148 | </p>
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| 149 | </entry>
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| 150 | <entry>
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| 151 | <p>
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| 152 | All of the above.
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| 153 | </p>
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| 154 | </entry>
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| 155 | <entry>
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| 156 | <p>
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| 157 | Tries all the available codes.
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| 158 | </p>
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| 159 | </entry>
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| 160 | </row>
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| 161 | </tbody>
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| 162 | </tgroup>
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| 163 | </table>
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| 164 | <p>To enable PC speaker passthrough use the following command: </p>
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| 165 | <pre xml:space="preserve">VBoxManage setextradata <varname>VM-name</varname> "VBoxInternal/Devices/i8254/0/Config/PassthroughSpeaker" <varname>N</varname>
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| 166 | </pre>
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| 167 | <p>Replace <varname>N</varname> with the code representing the case you want to use. Changing this setting takes
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| 168 | effect when you next start the VM. It is safe to enable PC speaker passthrough on all host OSes. It will only have
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| 169 | an effect on Linux. </p>
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| 170 | <p>The VM log file, <filepath>VBox.log</filepath>, contains lines with the prefix <codeph>PIT: speaker:</codeph>
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| 171 | showing the PC speaker passthrough setup activities. It gives hints which device it picked or why it failed. </p>
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| 172 | <p>Enabling PC speaker passthrough for the VM is usually the simple part. The real difficulty is making sure that
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| 173 | <ph conkeyref="vbox-conkeyref-phrases/product-name"/> can access the necessary device, because in a typical
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| 174 | Linux install most of them can only be accessed by user <codeph>root</codeph>. You should follow the preferred way
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| 175 | to persistently change this, such as by referring to your distribution's documentation. Since there are countless
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| 176 | Linux distribution variants, we can only give the general hints that there is often a way to give the X11 session
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| 177 | user access to additional devices, or you need to find a working solution using a udev configuration file. If
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| 178 | everything fails you might try setting the permissions using a script which is run late enough in the host system
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| 179 | startup. </p>
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| 180 | <p>Sometimes additional rules are applied by the kernel to limit access. For example, that the VM process must have
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| 181 | the same controlling terminal as the device configured to be used for beeping, something which is often very
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| 182 | difficult to achieve for GUI applications such as <ph conkeyref="vbox-conkeyref-phrases/product-name"/>. The table
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| 183 | above contains some hints, but in general refer to the Linux documentation. </p>
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| 184 | <p>If you have trouble getting any beeps even if the device permissions are set up and VBox.log confirms that it
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| 185 | uses evdev or console for the PC speaker control, check if your system has a PC speaker. Some systems do not have
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| 186 | one. Other complications can arise from Linux rerouting the PC speaker output to a sound card. Check if the beeps
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| 187 | are audible if you connect speakers to your sound card. Today almost all systems have one. Finally, check if the
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| 188 | audio mixer control has a channel named <i>beep</i>, which could be hidden in the mixer settings, and that it is
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| 189 | not muted. </p>
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| 190 | </body>
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| 191 |
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| 192 | </topic>
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