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authorJames Bottomley <James.Bottomley@HansenPartnership.com>2009-06-12 10:02:03 -0500
committerJames Bottomley <James.Bottomley@HansenPartnership.com>2009-06-12 10:02:03 -0500
commit82681a318f9f028ea64e61f24bbd9ac535531921 (patch)
tree529b6a5b4fd040fb54b7672b1a224ebd47445876 /Documentation/DMA-API.txt
parent3860c97bd60a4525bb62eb90e3e7d2f02662ac59 (diff)
parent8ebf975608aaebd7feb33d77f07ba21a6380e086 (diff)
[SCSI] Merge branch 'linus'
Conflicts: drivers/message/fusion/mptsas.c fixed up conflict between req->data_len accessors and mptsas driver updates. Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Diffstat (limited to 'Documentation/DMA-API.txt')
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diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index d9aa43d78bc..25fb8bcf32a 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -704,12 +704,24 @@ this directory the following files can currently be found:
The current number of free dma_debug_entries
in the allocator.
+ dma-api/driver-filter
+ You can write a name of a driver into this file
+ to limit the debug output to requests from that
+ particular driver. Write an empty string to
+ that file to disable the filter and see
+ all errors again.
+
If you have this code compiled into your kernel it will be enabled by default.
If you want to boot without the bookkeeping anyway you can provide
'dma_debug=off' as a boot parameter. This will disable DMA-API debugging.
Notice that you can not enable it again at runtime. You have to reboot to do
so.
+If you want to see debug messages only for a special device driver you can
+specify the dma_debug_driver=<drivername> parameter. This will enable the
+driver filter at boot time. The debug code will only print errors for that
+driver afterwards. This filter can be disabled or changed later using debugfs.
+
When the code disables itself at runtime this is most likely because it ran
out of dma_debug_entries. These entries are preallocated at boot. The number
of preallocated entries is defined per architecture. If it is too low for you