Adds support to compile QEMU with multiple tracing backends at the same time.
For example, you can compile QEMU with:
$ ./configure --enable-trace-backends=ftrace,dtrace
Where 'ftrace' can be handy for having an in-flight record of events, and 'dtrace' can be later used to extract more information from the system.
This patch allows having both available without recompiling QEMU.
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The backend is forced to dump event numbers using 64 bits, as TraceEventID is
an enum.
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Existing simpletrace backend allows to trace at max 6 args and does not
support strings. This newer tracelog format gets rid of fixed size records
and therefore allows to trace variable number of args including strings.
Sample trace with strings:
v9fs_version 0.000 tag=0xffff id=0x64 msize=0x2000 version=9P2000.L
v9fs_version_return 6.705 tag=0xffff id=0x64 msize=0x2000 version=9P2000.L
Signed-off-by: Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Going forward with simpletrace v2 variable size trace records, we cannot
have a generic function to print trace event info and therefore this
interface becomes invalid.
As per Stefan Hajnoczi:
"This command is only available from the human monitor. It's not very
useful because it historically hasn't been able to pretty-print events
or show them in the right order (we use a ringbuffer but it prints
them out from index 0).
Therefore, I don't think we're under any obligation to keep this
command around. No one has complained about it's limitations - I
think this is a sign that no one has used it. I'd be okay with a
patch that removes it."
Ref: http://lists.gnu.org/archive/html/qemu-devel/2012-01/msg01268.html
Signed-off-by: Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Generalize the 'st_print_trace_events' and 'st_change_trace_event_state' into
backend-specific 'trace_print_events' and 'trace_event_set_state' (respectively)
in the "trace/control.h" file.
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
A default implementation for backend-specific routines is provided in
"trace/default.c", which backends can override by setting "trace_default=no" in
"configure".
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
