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Diffstat (limited to 'Documentation/trace/debugging.rst')
| -rw-r--r-- | Documentation/trace/debugging.rst | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/Documentation/trace/debugging.rst b/Documentation/trace/debugging.rst index 54fb16239d70..4d88c346fc38 100644 --- a/Documentation/trace/debugging.rst +++ b/Documentation/trace/debugging.rst @@ -59,7 +59,7 @@ There is various methods of acquiring the state of the system when a kernel crash occurs. This could be from the oops message in printk, or one could use kexec/kdump. But these just show what happened at the time of the crash. It can be very useful in knowing what happened up to the point of the crash. -The tracing ring buffer, by default, is a circular buffer than will +The tracing ring buffer, by default, is a circular buffer that will overwrite older events with newer ones. When a crash happens, the content of the ring buffer will be all the events that lead up to the crash. @@ -136,6 +136,8 @@ kernel, so only the same kernel is guaranteed to work if the mapping is preserved. Switching to a different kernel version may find a different layout and mark the buffer as invalid. +NB: Both the mapped address and size must be page aligned for the architecture. + Using trace_printk() in the boot instance ----------------------------------------- By default, the content of trace_printk() goes into the top level tracing |