diff options
Diffstat (limited to 'sys/i386/isa/sound/Readme.modules')
| -rw-r--r-- | sys/i386/isa/sound/Readme.modules | 186 |
1 files changed, 99 insertions, 87 deletions
diff --git a/sys/i386/isa/sound/Readme.modules b/sys/i386/isa/sound/Readme.modules index 315540f510c1..2dab12552d1b 100644 --- a/sys/i386/isa/sound/Readme.modules +++ b/sys/i386/isa/sound/Readme.modules @@ -1,87 +1,99 @@ - Linux sound-driver module - (c) Peter Trattler - License: GPL (Gnu Public License) - - -Idea: - -I've modified the sources for the sound driver to allow simply insert and -remove the sound driver from the kernel by calling (only available for Linux) - - insmod /usr/src/linux/modules/sound.o - -and - - rmmod sound - -This may be useful if you are doing one of the following things: - -1) Debugging the sound driver -2) Creating a new device within the sound-driver -3) You do not the sound driver all the time (as it wastes quite a lot of -memory for its buffers) - - -Compilation: - -Go to /usr/src/linux and make the following steps: - -a) configure the sound driver: To do that call "make config" and enable the -sound-driver -- you will be asked different questions about your -sound-hardware (remember not to use a too big DMA-Buffer size; you -should use 16kB, if you have 16Bit devices, otherwise you can use 32kB) - -b) disable the sound driver in the kernel: call make config again but answer -'N' to "Sound card support" - -c) run "make modules"; the sound-driver sound.o should end up in -/usr/src/linux/modules - - -If memory is tight: - -I've allocated at about 70kB for the sound-drivers internal tables. If this -is too much, 'insmod sound.o' will generate the following warning -... -use 'insmod memsize=xxxx' -... -You can only use this command, if you have (I think) at least -modules-1.1.87 or up. You can also switch debugging on by running the command - -insmod sound.o debugmem=1 - - -Files I changed: - -I've only changed the files soundcard.c(most changes) and some changes within -the Makefile, sound_config.h and the Makefile in /usr/src/linux/drivers - - -Bugs: - -a) As the kmalloc (..., GFP_DMA) caused some unexpected errors (I don't know if -it is my fault), I created some code, which is (by default) enabled by - -#define KMALLOC_DMA_BROKEN 1 (within soundcard.c). - -It trys to allocate a large enough region, so that the complete dma-buffer -can be occupied in this space. If it does not fit within this region it -doubles the size of it. But this can cause problems, if the sound-buffer is -too big (as kmalloc can only handle regions at up to circa 100kB). - -So take care to use for 8Bit devices a sound-DMA-buffer of 32kB (maximum) -and for 16Bit devices a maximum of 16kB. Otherwise the allocation scheme -might fail. - -b) Buffers allocated by the different sound devices via calls to kmalloc are -not freed, if the sound driver is removed again (these buffers tend to be -quite small -- so it does not harm a lot) - -c) If there is not enough (kernel-) memory available, the installation of -the sound-driver fails. (This happens quite often, if you did not install the -driver right after booting -- [PS: I've only got 5MB of Ram, so this might -be the source for this problem]) - - -Author: - Peter Trattler (peter@sbox.tu-graz.ac.at) +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 |