patch-1.3.9 linux/drivers/sound/Readme.modules

• Lines: 88
• Date: Wed Jan 2 02:30:41 1980
• Orig file: v1.3.8/linux/drivers/sound/Readme.modules
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.8/linux/drivers/sound/Readme.modules linux/drivers/sound/Readme.modules
@@ -0,0 +1,87 @@
+			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)