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Diffstat (limited to 'sys/i386/isa/sound/Readme.modules')
| -rw-r--r-- | sys/i386/isa/sound/Readme.modules | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/sys/i386/isa/sound/Readme.modules b/sys/i386/isa/sound/Readme.modules new file mode 100644 index 0000000..2dab125 --- /dev/null +++ b/sys/i386/isa/sound/Readme.modules @@ -0,0 +1,99 @@ +Building a loadable sound driver +================================ + +Loadable module support in version 3.5 of VoxWare is mostly rewritten since +the previous version (3.0.1). This means that some things have changed. + +To compile the sound driver as a loadable module you have to perform +the following steps: + +1) Install modules-1.2.8.tar.gz package (or later if available). +2a) Check that symbol remap_page_range is defined in linux/init/ksyms.c. +Insert a line containing "X(remap_page_range)," if required. The driver will +not load if this line is missing. +2b) Recompile kernel with soundcard support disabled. +3) Boot the new kernel. +4) cd to the sound driver source directory (this directory). It's no +longer required that the sound driver sources are installed in the +kernel source tree (linux/drivers/sound). When installing a separately +distributed sound driver you may install the sources for example to +/usr/src/sound. +5) Execute make in the sound driver source directory. Enter +configuration parameters as described in Readme.cards. Then just wait until +the driver is compiled OK. +6) Copy sound.o to the directory where insmod expects to find it. +("make install" copies it to /lib/modules/misc). +7) Use command "insmod sound" to load the driver. + +8) The sound driver can be removed using command "rmmod sound". + + +Parameters accepted by the loadable sound driver +================================================ + +Setting DMA buffer size +----------------------- + +The driver allocates a DMA buffer (or two for full duplex devices) +every time the audio device (/dev/dsp or /dev/audio) is opened +and frees it when the device is closed. Size of this buffer is defined +when the driver is configured (the last question). The buffer size +can be redefined when loading the driver if required (note that this is +an optional feature which is not normally required). The buffer size +is redefined by adding dma_pagesize= parameter to the insmod command line. +For example: + + insmod sound dma_buffsize=32768 + +Minimum buffer size is 4096 and the maximum depends on the DMA channe. +For 8 bit channels (0 to 3) the limit is 64k and for 16 bit ones (5 to 7) +it's 128k. Driver selects a suitable buffer size automaticly in case +you try to spesify an invalid size. + +Q: What is the right DMA buffer size? + +A: It depends on the sampling rate, machine speed and the load of the system. +Large buffers are required on slow machines, when recording/playing CD-quality +audio or when there are other processes running on the same system. Also +recording to hard disk is likely to require large buffers. + +Very small buffers are sufficient when you are just playing 8kHz audio files +on an empty P133 system. Using a 128k byffer just wastes 120k (or 250k) +of valuable physical RAM memory. + +The right buffer sice can be easily found by making some experiments +with the dma_buffsize= parameter. I use usually 16k buffers on a DX4/100 system +and 64k on an old 386 system. + +NOTE! DMA buffers are used only by /dev/audio# and /dev/dsp# devices. + Other device files don't use them but there are two exceptions: + GUS driver uses DMA buffers when loading samples to the card. + Ensoniq SoundScape driver uses them when doanloading the microcode + file (sndscape.co[012]) to the card. Using large buffers doesn't + increase performance in these cases. + +Configuring device parameters when loading the driver +----------------------------------------------------- + +The loadable version of the sound driver accepts now the same +sound= parameter that has been available in the LILO command line. +In this way it's possible to change I/O port, IRQ and DMA addresses +and to enable/disable various cards at load time. Normally +the driver uses the configuration parameters entered when compiling +and configuring the driver. +Look at Readme.linux for more info. + +NOTE! This method is not normally required. You should use it only when + you have to use different configuration than normally. The sound= + command line parameter is error phrone and not recommended. + +Debugging and tracing +--------------------- + +Modularized sound driver doesn't display messages during initialization as +the kernel compiled one does. This feature can be turned on by adding +init_trace=1 to the insmod command line. + +For example: + + insmod sound init_trace=1 |
