diff options
Diffstat (limited to 'docs/src/interface/debugging.tex')
| -rw-r--r-- | docs/src/interface/debugging.tex | 62 |
1 files changed, 0 insertions, 62 deletions
diff --git a/docs/src/interface/debugging.tex b/docs/src/interface/debugging.tex deleted file mode 100644 index 3be773652e..0000000000 --- a/docs/src/interface/debugging.tex +++ /dev/null @@ -1,62 +0,0 @@ -\chapter{Debugging} - -Xen provides tools for debugging both Xen and guest OSes. Currently, the -Pervasive Debugger provides a GDB stub, which provides facilities for symbolic -debugging of Xen itself and of OS kernels running on top of Xen. The Trace -Buffer provides a lightweight means to log data about Xen's internal state and -behaviour at runtime, for later analysis. - -\section{Pervasive Debugger} - -Information on using the pervasive debugger is available in pdb.txt. - - -\section{Trace Buffer} - -The trace buffer provides a means to observe Xen's operation from domain 0. -Trace events, inserted at key points in Xen's code, record data that can be -read by the {\tt xentrace} tool. Recording these events has a low overhead -and hence the trace buffer may be useful for debugging timing-sensitive -behaviours. - -\subsection{Internal API} - -To use the trace buffer functionality from within Xen, you must {\tt \#include -<xen/trace.h>}, which contains definitions related to the trace buffer. Trace -events are inserted into the buffer using the {\tt TRACE\_xD} ({\tt x} = 0, 1, -2, 3, 4 or 5) macros. These all take an event number, plus {\tt x} additional -(32-bit) data as their arguments. For trace buffer-enabled builds of Xen these -will insert the event ID and data into the trace buffer, along with the current -value of the CPU cycle-counter. For builds without the trace buffer enabled, -the macros expand to no-ops and thus can be left in place without incurring -overheads. - -\subsection{Trace-enabled builds} - -By default, the trace buffer is enabled only in debug builds (i.e. {\tt NDEBUG} -is not defined). It can be enabled separately by defining {\tt TRACE\_BUFFER}, -either in {\tt <xen/config.h>} or on the gcc command line. - -The size (in pages) of the per-CPU trace buffers can be specified using the -{\tt tbuf\_size=n } boot parameter to Xen. If the size is set to 0, the trace -buffers will be disabled. - -\subsection{Dumping trace data} - -When running a trace buffer build of Xen, trace data are written continuously -into the buffer data areas, with newer data overwriting older data. This data -can be captured using the {\tt xentrace} program in domain 0. - -The {\tt xentrace} tool uses {\tt /dev/mem} in domain 0 to map the trace -buffers into its address space. It then periodically polls all the buffers for -new data, dumping out any new records from each buffer in turn. As a result, -for machines with multiple (logical) CPUs, the trace buffer output will not be -in overall chronological order. - -The output from {\tt xentrace} can be post-processed using {\tt -xentrace\_cpusplit} (used to split trace data out into per-cpu log files) and -{\tt xentrace\_format} (used to pretty-print trace data). For the predefined -trace points, there is an example format file in {\tt tools/xentrace/formats }. - -For more information, see the manual pages for {\tt xentrace}, {\tt -xentrace\_format} and {\tt xentrace\_cpusplit}. |