X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=Documentation%2Fs390%2Fs390dbf.txt;h=0eb7c58916de4821abf9c954753567efac58f375;hb=97bf2856c6014879bd04983a3e9dfcdac1e7fe85;hp=e321a8ed2a2d6bf78581673b967cc9fe45186435;hpb=76828883507a47dae78837ab5dec5a5b4513c667;p=linux-2.6.git diff --git a/Documentation/s390/s390dbf.txt b/Documentation/s390/s390dbf.txt index e321a8ed2..0eb7c5891 100644 --- a/Documentation/s390/s390dbf.txt +++ b/Documentation/s390/s390dbf.txt @@ -11,7 +11,7 @@ where log records can be stored efficiently in memory, where each component (e.g. device drivers) can have one separate debug log. One purpose of this is to inspect the debug logs after a production system crash in order to analyze the reason for the crash. -If the system still runs but only a subcomponent which uses dbf failes, +If the system still runs but only a subcomponent which uses dbf fails, it is possible to look at the debug logs on a live system via the Linux debugfs filesystem. The debug feature may also very useful for kernel and driver development. @@ -36,7 +36,7 @@ switches to the next debug area. This is done in order to be sure that the records which describe the origin of the exception are not overwritten when a wrap around for the current area occurs. -The debug areas itselve are also ordered in form of a ring buffer. +The debug areas themselves are also ordered in form of a ring buffer. When an exception is thrown in the last debug area, the following debug entries are then written again in the very first area. @@ -55,7 +55,7 @@ The debug logs can be inspected in a live system through entries in the debugfs-filesystem. Under the toplevel directory "s390dbf" there is a directory for each registered component, which is named like the corresponding component. The debugfs normally should be mounted to -/sys/kernel/debug therefore the debug feature can be accessed unter +/sys/kernel/debug therefore the debug feature can be accessed under /sys/kernel/debug/s390dbf. The content of the directories are files which represent different views @@ -65,7 +65,7 @@ Predefined views for hex/ascii, sprintf and raw binary data are provided. It is also possible to define other views. The content of a view can be inspected simply by reading the corresponding debugfs file. -All debug logs have an an actual debug level (range from 0 to 6). +All debug logs have an actual debug level (range from 0 to 6). The default level is 3. Event and Exception functions have a 'level' parameter. Only debug entries with a level that is lower or equal than the actual level are written to the log. This means, when @@ -83,15 +83,15 @@ Example: It is also possible to deactivate the debug feature globally for every debug log. You can change the behavior using 2 sysctl parameters in /proc/sys/s390dbf: -There are currently 2 possible triggers, which stop the debug feature -globally. The first possbility is to use the "debug_active" sysctl. If +There are currently 2 possible triggers, which stop the debug feature +globally. The first possibility is to use the "debug_active" sysctl. If set to 1 the debug feature is running. If "debug_active" is set to 0 the debug feature is turned off. -The second trigger which stops the debug feature is an kernel oops. +The second trigger which stops the debug feature is a kernel oops. That prevents the debug feature from overwriting debug information that happened before the oops. After an oops you can reactivate the debug feature by piping 1 to /proc/sys/s390dbf/debug_active. Nevertheless, its not -suggested to use an oopsed kernel in an production environment. +suggested to use an oopsed kernel in a production environment. If you want to disallow the deactivation of the debug feature, you can use the "debug_stoppable" sysctl. If you set "debug_stoppable" to 0 the debug feature cannot be stopped. If the debug feature is already stopped, it @@ -468,7 +468,7 @@ The hex_ascii view shows the data field in hex and ascii representation The raw view returns a bytestream as the debug areas are stored in memory. The sprintf view formats the debug entries in the same way as the sprintf -function would do. The sprintf event/expection functions write to the +function would do. The sprintf event/exception functions write to the debug entry a pointer to the format string (size = sizeof(long)) and for each vararg a long value. So e.g. for a debug entry with a format string plus two varargs one would need to allocate a (3 * sizeof(long)) @@ -556,7 +556,7 @@ The input_proc can be used to implement functionality when it is written to the view (e.g. like with 'echo "0" > /sys/kernel/debug/s390dbf/dasd/level). For header_proc there can be used the default function -debug_dflt_header_fn() which is defined in in debug.h. +debug_dflt_header_fn() which is defined in debug.h. and which produces the same header output as the predefined views. E.g: 00 00964419409:440761 2 - 00 88023ec