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| author | Ingo Molnar <mingo@elte.hu> | 2009-06-07 11:36:02 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-06-07 11:36:02 +0200 |
| commit | 62a6f465f6572e1f28765c583c12753bb3e23715 (patch) | |
| tree | 35ccf596b4abbeec9e1244f31e5b4e5d079899f5 /Documentation | |
| parent | 56fdd18c7b89a2fac1dfe5d54750c9143867fdc4 (diff) | |
| parent | bdc2911cde7d18580a545483844d75fdb3551729 (diff) | |
Merge branch 'dma-debug/2.6.31' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/linux-2.6-iommu into core/iommu
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DMA-API.txt | 12 | ||||
| -rw-r--r-- | Documentation/kernel-parameters.txt | 7 |
2 files changed, 19 insertions, 0 deletions
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 diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index e2999cb4745..8f9e17c855a 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -641,6 +641,13 @@ and is between 256 and 4096 characters. It is defined in the file DMA-API debugging code disables itself because the architectural default is too low. + dma_debug_driver=<driver_name> + With this option the DMA-API debugging driver + filter feature can be enabled at boot time. Just + pass the driver to filter for as the parameter. + The filter can be disabled or changed to another + driver later using sysfs. + dscc4.setup= [NET] dtc3181e= [HW,SCSI] |