[Qemu-devel] [PATCH 0/2] Add support for SystemTAP and DTrace tracing backends

[Qemu-devel] [PATCH 0/2] Add support for SystemTAP and DTrace tracing backends

[Daniel P. Berrange]

This is an update of the SystemTAP/DTrace patches previously sent

  http://lists.gnu.org/archive/html/qemu-devel/2010-10/msg01451.html

The patch is now split into two pieces. 

The first patch contains the generic DTrace tracing backend support.

The second patch contains additional pieces for SystemTAP to generate
a tapset for each of the qemu-system-XXX binaries, to simplify life
for admins wanting to use the tracing backend. This addresses the 
problem in previous versions of the patch where the tapset only worked 
for /usr/bin/qemu and no other binaries. Unfortunately SystemTAP does 
not allow for use of wildcards, so it was neccessary to go for a separate 
tapset file per emulator binary.

Regards,
Daniel

[Qemu-devel] [PATCH 1/2] Add a DTrace tracing backend targetted for SystemTAP compatability

[Daniel P. Berrange]

From: Daniel P. Berrange <berrange@redhat.com>

This introduces a new tracing backend that targets the SystemTAP
implementation of DTrace userspace tracing. The core functionality
should be applicable and standard across any DTrace implementation
on Solaris, OS-X, *BSD, but the Makefile rules will likely need
some small additional changes to cope with OS specific build
requirements.

This backend builds a little differently from the other tracing
backends. Specifically there is no 'trace.c' file, because the
'dtrace' command line tool generates a '.o' file directly from
the dtrace probe definition file. The probe definition is usually
named with a '.d' extension but QEMU uses '.d' files for its
external makefile dependancy tracking, so this uses '.dtrace' as
the extension for the probe definition file.

The 'tracetool' program gains the ability to generate a trace.h
file for DTrace, and also to generate the trace.d file containing
the dtrace probe definition.

Example usage of a dtrace probe in systemtap looks like:

  probe process("qemu").mark("qemu_malloc") {
    printf("Malloc %d %p\n", $arg1, $arg2);
  }

* .gitignore: Ignore trace-dtrace.*
* Makefile: Extra rules for generating DTrace files
* Makefile.obj: Don't build trace.o for DTrace, use
  trace-dtrace.o generated by 'dtrace' instead
* tracetool: Support for generating DTrace data files

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 .gitignore    |    2 +
 Makefile      |   24 ++++++++++++
 Makefile.objs |    4 ++
 configure     |   14 ++++++-
 tracetool     |  116 ++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 5 files changed, 149 insertions(+), 11 deletions(-)

diff --git a/.gitignore b/.gitignore
index a43e4d1..3efb4ec 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,6 +4,8 @@ config-host.*
 config-target.*
 trace.h
 trace.c
+trace-dtrace.h
+trace-dtrace.dtrace
 *-timestamp
 *-softmmu
 *-darwin-user
diff --git a/Makefile b/Makefile
index 02698e9..384bf72 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,10 @@
 # Makefile for QEMU.
 
 GENERATED_HEADERS = config-host.h trace.h qemu-options.def
+GENERATED_HEADERS = config-host.h trace.h
+ifeq ($(TRACE_BACKEND),dtrace)
+GENERATED_HEADERS += trace-dtrace.h
+endif
 
 ifneq ($(wildcard config-host.mak),)
 # Put the all: rule here so that config-host.mak can contain dependencies.
@@ -108,7 +112,11 @@ ui/vnc.o: QEMU_CFLAGS += $(VNC_TLS_CFLAGS)
 
 bt-host.o: QEMU_CFLAGS += $(BLUEZ_CFLAGS)
 
+ifeq ($(TRACE_BACKEND),dtrace)
+trace.h: trace.h-timestamp trace-dtrace.h
+else
 trace.h: trace.h-timestamp
+endif
 trace.h-timestamp: $(SRC_PATH)/trace-events config-host.mak
 	$(call quiet-command,sh $(SRC_PATH)/tracetool --$(TRACE_BACKEND) -h < $< > $@,"  GEN   trace.h")
 	@cmp -s $@ trace.h || cp $@ trace.h
@@ -120,6 +128,20 @@ trace.c-timestamp: $(SRC_PATH)/trace-events config-host.mak
 
 trace.o: trace.c $(GENERATED_HEADERS)
 
+trace-dtrace.h: trace-dtrace.dtrace
+	$(call quiet-command,dtrace -o $@ -h -s $<, "  GEN   trace-dtrace.h")
+
+# Normal practice is to name DTrace probe file with a '.d' extension
+# but that gets picked up by QEMU's Makefile as an external dependancy
+# rule file. So we use '.dtrace' instead
+trace-dtrace.dtrace: trace-dtrace.dtrace-timestamp
+trace-dtrace.dtrace-timestamp: $(SRC_PATH)/trace-events config-host.mak
+	$(call quiet-command,sh $(SRC_PATH)/tracetool --$(TRACE_BACKEND) -d < $< > $@,"  GEN   trace-dtrace.dtrace")
+	@cmp -s $@ trace-dtrace.dtrace || cp $@ trace-dtrace.dtrace
+
+trace-dtrace.o: trace-dtrace.dtrace $(GENERATED_HEADERS)
+	$(call quiet-command,dtrace -o $@ -G -s $<, "  GEN trace-dtrace.o")
+
 simpletrace.o: simpletrace.c $(GENERATED_HEADERS)
 
 version.o: $(SRC_PATH)/version.rc config-host.mak
@@ -157,6 +179,8 @@ clean:
 	rm -f slirp/*.o slirp/*.d audio/*.o audio/*.d block/*.o block/*.d net/*.o net/*.d fsdev/*.o fsdev/*.d ui/*.o ui/*.d
 	rm -f qemu-img-cmds.h
 	rm -f trace.c trace.h trace.c-timestamp trace.h-timestamp
+	rm -f trace-dtrace.dtrace trace-dtrace.dtrace-timestamp
+	rm -f trace-dtrace.h trace-dtrace.h-timestamp
 	$(MAKE) -C tests clean
 	for d in $(ALL_SUBDIRS) libhw32 libhw64 libuser libdis libdis-user; do \
 	if test -d $$d; then $(MAKE) -C $$d $@ || exit 1; fi; \
diff --git a/Makefile.objs b/Makefile.objs
index faf485e..84fc80e 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -285,11 +285,15 @@ libdis-$(CONFIG_SPARC_DIS) += sparc-dis.o
 ######################################################################
 # trace
 
+ifeq ($(TRACE_BACKEND),dtrace)
+trace-obj-y = trace-dtrace.o
+else
 trace-obj-y = trace.o
 ifeq ($(TRACE_BACKEND),simple)
 trace-obj-y += simpletrace.o
 user-obj-y += qemu-timer-common.o
 endif
+endif
 
 vl.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)
 
diff --git a/configure b/configure
index 7025d2b..f8dad3e 100755
--- a/configure
+++ b/configure
@@ -929,7 +929,7 @@ echo "  --enable-docs            enable documentation build"
 echo "  --disable-docs           disable documentation build"
 echo "  --disable-vhost-net      disable vhost-net acceleration support"
 echo "  --enable-vhost-net       enable vhost-net acceleration support"
-echo "  --trace-backend=B        Trace backend nop simple ust"
+echo "  --trace-backend=B        Trace backend nop simple ust dtrace"
 echo "  --trace-file=NAME        Full PATH,NAME of file to store traces"
 echo "                           Default:trace-<pid>"
 echo "  --disable-spice          disable spice"
@@ -2193,6 +2193,18 @@ EOF
     exit 1
   fi
 fi
+
+##########################################
+# For 'dtrace' backend, test if 'dtrace' command is present
+if test "$trace_backend" = "dtrace"; then
+  if ! has 'dtrace' ; then
+    echo
+    echo "Error: dtrace command is not found in PATH $PATH"
+    echo
+    exit 1
+  fi
+fi
+
 ##########################################
 # End of CC checks
 # After here, no more $cc or $ld runs
diff --git a/tracetool b/tracetool
index 7010858..5b6636a 100755
--- a/tracetool
+++ b/tracetool
@@ -20,10 +20,12 @@ Backends:
   --nop     Tracing disabled
   --simple  Simple built-in backend
   --ust     LTTng User Space Tracing backend
+  --dtrace  DTrace/SystemTAP backend
 
 Output formats:
   -h    Generate .h file
   -c    Generate .c file
+  -d    Generate .d file (DTrace only)
 EOF
     exit 1
 }
@@ -46,8 +48,9 @@ get_args()
 # Get the argument name list of a trace event
 get_argnames()
 {
-    local nfields field name
+    local nfields field name sep
     nfields=0
+    sep="$2"
     for field in $(get_args "$1"); do
         nfields=$((nfields + 1))
 
@@ -58,7 +61,7 @@ get_argnames()
         name=${field%,}
         test "$field" = "$name" && continue
 
-        printf "%s" "$name, "
+        printf "%s%s " $name $sep
     done
 
     # Last argument name
@@ -73,7 +76,7 @@ get_argc()
 {
     local name argc
     argc=0
-    for name in $(get_argnames "$1"); do
+    for name in $(get_argnames "$1", ","); do
         argc=$((argc + 1))
     done
     echo $argc
@@ -154,7 +157,7 @@ EOF
 cast_args_to_uint64_t()
 {
     local arg
-    for arg in $(get_argnames "$1"); do
+    for arg in $(get_argnames "$1", ","); do
         printf "%s" "(uint64_t)(uintptr_t)$arg"
     done
 }
@@ -247,7 +250,7 @@ linetoh_ust()
     local name args argnames
     name=$(get_name "$1")
     args=$(get_args "$1")
-    argnames=$(get_argnames "$1")
+    argnames=$(get_argnames "$1", ",")
 
     cat <<EOF
 DECLARE_TRACE(ust_$name, TP_PROTO($args), TP_ARGS($argnames));
@@ -274,7 +277,7 @@ linetoc_ust()
     local name args argnames fmt
     name=$(get_name "$1")
     args=$(get_args "$1")
-    argnames=$(get_argnames "$1")
+    argnames=$(get_argnames "$1", ",")
     fmt=$(get_fmt "$1")
 
     cat <<EOF
@@ -306,6 +309,87 @@ EOF
     echo "}"
 }
 
+linetoh_begin_dtrace()
+{
+    cat <<EOF
+#include "trace-dtrace.h"
+EOF
+}
+
+linetoh_dtrace()
+{
+    local name args argnames state nameupper
+    name=$(get_name "$1")
+    args=$(get_args "$1")
+    argnames=$(get_argnames "$1", ",")
+    state=$(get_state "$1")
+    if [ "$state" = "0" ] ; then
+        name=${name##disable }
+    fi
+
+    nameupper=`echo $name | tr '[:lower:]' '[:upper:]'`
+
+    # Define an empty function for the trace event
+    cat <<EOF
+static inline void trace_$name($args) {
+    if (QEMU_${nameupper}_ENABLED()) {
+        QEMU_${nameupper}($argnames);
+    }
+}
+EOF
+}
+
+linetoh_end_dtrace()
+{
+    return
+}
+
+linetoc_begin_dtrace()
+{
+    return
+}
+
+linetoc_dtrace()
+{
+    # No need for function definitions in dtrace backend
+    return
+}
+
+linetoc_end_dtrace()
+{
+    return
+}
+
+linetod_begin_dtrace()
+{
+    cat <<EOF
+provider qemu {
+EOF
+}
+
+linetod_dtrace()
+{
+    local name args state
+    name=$(get_name "$1")
+    args=$(get_args "$1")
+    state=$(get_state "$1")
+    if [ "$state" = "0" ] ; then
+        name=${name##disable }
+    fi
+
+    # Define prototype for probe arguments
+    cat <<EOF
+        probe $name($args);
+EOF
+}
+
+linetod_end_dtrace()
+{
+    cat <<EOF
+};
+EOF
+}
+
 # Process stdin by calling begin, line, and end functions for the backend
 convert()
 {
@@ -324,9 +408,10 @@ convert()
         disable=${str%%disable *}
         echo
         if test -z "$disable"; then
-            # Pass the disabled state as an arg to lineto$1_simple().
-            # For all other cases, call lineto$1_nop()
-            if [ $backend = "simple" ]; then
+            # Pass the disabled state as an arg for the simple
+            # or DTrace backends which handle it dynamically.
+            # For all other backends, call lineto$1_nop()
+            if [ $backend = "simple" -o "$backend" = "dtrace" ]; then
                 "$process_line" "$str"
             else
                 "lineto$1_nop" "${str##disable }"
@@ -360,9 +445,19 @@ tracetoc()
     convert c
 }
 
+tracetod()
+{
+    if [ $backend != "dtrace" ]; then
+       echo "DTrace probe generator not applicable to $backend backend"
+       exit 1
+    fi
+    echo "/* This file is autogenerated by tracetool, do not edit. */"
+    convert d
+}
+
 # Choose backend
 case "$1" in
-"--nop" | "--simple" | "--ust") backend="${1#--}" ;;
+"--nop" | "--simple" | "--ust" | "--dtrace") backend="${1#--}" ;;
 *) usage ;;
 esac
 shift
@@ -370,6 +465,7 @@ shift
 case "$1" in
 "-h") tracetoh ;;
 "-c") tracetoc ;;
+"-d") tracetod ;;
 "--check-backend") exit 0 ;; # used by ./configure to test for backend
 *) usage ;;
 esac
-- 
1.7.2.3

[Qemu-devel] [PATCH 2/2] Add support for generating a systemtap tapset static probes

[Daniel P. Berrange]

From: Daniel P. Berrange <berrange@redhat.com>

This introduces generation of a qemu.stp/qemu-system-XXX.stp
files which provides tapsets with friendly names for static
probes & their arguments. Instead of

    probe process("qemu").mark("qemu_malloc") {
        printf("Malloc %d %p\n", $arg1, $arg2);
    }

It is now possible todo

    probe qemu.system.i386.qemu_malloc {
        printf("Malloc %d %p\n", size, ptr);
    }

There is one tapset defined per target arch.

* Makefile: Generate a qemu.stp file for systemtap
* tracetool: Support for generating systemtap tapsets

Signed-off-by: Daniel P. Berrange <dan@berrange.com>
---
 Makefile.target |   19 +++++++++++-
 configure       |    7 ++++
 tracetool       |   92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 117 insertions(+), 1 deletions(-)

diff --git a/Makefile.target b/Makefile.target
index 91e6e74..a5e6410 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -40,7 +40,20 @@ kvm.o kvm-all.o vhost.o vhost_net.o: QEMU_CFLAGS+=$(KVM_CFLAGS)
 config-target.h: config-target.h-timestamp
 config-target.h-timestamp: config-target.mak
 
-all: $(PROGS)
+ifdef CONFIG_SYSTEMTAP_TRACE
+trace: $(QEMU_PROG).stp
+
+$(QEMU_PROG).stp:
+	$(call quiet-command,sh $(SRC_PATH)/tracetool \
+		--$(TRACE_BACKEND) \
+		--bindir $(bindir) \
+		--target $(TARGET_ARCH) \
+		-s < $(SRC_PATH)/trace-events > $(QEMU_PROG).stp,"  GEN   $(QEMU_PROG).stp")
+else
+trace:
+endif
+
+all: $(PROGS) trace
 
 # Dummy command so that make thinks it has done something
 	@true
@@ -348,6 +361,10 @@ ifneq ($(STRIP),)
 	$(STRIP) $(patsubst %,"$(DESTDIR)$(bindir)/%",$(PROGS))
 endif
 endif
+ifdef CONFIG_SYSTEMTAP_TRACE
+	$(INSTALL_DIR) "$(DESTDIR)$(datadir)/../systemtap/tapset"
+	$(INSTALL_DATA) $(QEMU_PROG).stp "$(DESTDIR)$(datadir)/../systemtap/tapset"
+endif
 
 # Include automatically generated dependency files
 -include $(wildcard *.d */*.d)
diff --git a/configure b/configure
index f8dad3e..e560f87 100755
--- a/configure
+++ b/configure
@@ -2192,6 +2192,10 @@ EOF
     echo
     exit 1
   fi
+  trace_backend_stap="no"
+  if has 'stap' ; then
+    trace_backend_stap="yes"
+  fi
 fi
 
 ##########################################
@@ -2645,6 +2649,9 @@ fi
 if test "$trace_backend" = "simple"; then
   trace_file="\"$trace_file-%u\""
 fi
+if test "$trace_backend" = "dtrace" -a "$trace_backend_stap" = "yes" ; then
+  echo "CONFIG_SYSTEMTAP_TRACE=y" >> $config_host_mak
+fi
 echo "CONFIG_TRACE_FILE=$trace_file" >> $config_host_mak
 
 echo "TOOLS=$tools" >> $config_host_mak
diff --git a/tracetool b/tracetool
index 5b6636a..d797ab7 100755
--- a/tracetool
+++ b/tracetool
@@ -26,6 +26,12 @@ Output formats:
   -h    Generate .h file
   -c    Generate .c file
   -d    Generate .d file (DTrace only)
+  -s    Generate .stp file (DTrace with SystemTAP only)
+
+Options:
+  --bindir [bindir]  QEMU binary install location
+  --target [arch]    QEMU target architecture
+
 EOF
     exit 1
 }
@@ -390,6 +396,54 @@ linetod_end_dtrace()
 EOF
 }
 
+linetos_begin_dtrace()
+{
+    return
+}
+
+linetos_dtrace()
+{
+    local name args arglist state
+    name=$(get_name "$1")
+    args=$(get_args "$1")
+    arglist=$(get_argnames "$1", "")
+    state=$(get_state "$1")
+    if [ "$state" = "0" ] ; then
+        name=${name##disable }
+    fi
+
+    if [ "$target" = "i386" ]
+    then
+      binary="qemu"
+    else
+      binary="qemu-system-$target"
+    fi
+
+    # Define prototype for probe arguments
+    cat <<EOF
+probe qemu.system.$target.$name = process("$bindir/$binary").mark("$name")
+{
+EOF
+
+    i=1
+    for arg in $arglist
+    do
+        cat <<EOF
+  $arg = \$arg$i;
+EOF
+	i="$((i+1))"
+    done
+
+    cat <<EOF
+}
+EOF
+}
+
+linetos_end_dtrace()
+{
+    return
+}
+
 # Process stdin by calling begin, line, and end functions for the backend
 convert()
 {
@@ -455,6 +509,24 @@ tracetod()
     convert d
 }
 
+tracetos()
+{
+    if [ $backend != "dtrace" ]; then
+       echo "SystemTAP tapset generator not applicable to $backend backend"
+       exit 1
+    fi
+    if [ -z "$target" ]; then
+       echo "--target is required for SystemTAP tapset generator"
+       exit 1
+    fi
+    if [ -z "$bindir" ]; then
+       echo "--bindir is required for SystemTAP tapset generator"
+       exit 1
+    fi
+    echo "/* This file is autogenerated by tracetool, do not edit. */"
+    convert s
+}
+
 # Choose backend
 case "$1" in
 "--nop" | "--simple" | "--ust" | "--dtrace") backend="${1#--}" ;;
@@ -462,10 +534,30 @@ case "$1" in
 esac
 shift
 
+bindir=
+case "$1" in
+  "--bindir")
+    bindir=$2
+    shift
+    shift
+    ;;
+esac
+
+target=
+case "$1" in
+  "--target")
+    target=$2
+    shift
+    shift
+    ;;
+esac
+
+
 case "$1" in
 "-h") tracetoh ;;
 "-c") tracetoc ;;
 "-d") tracetod ;;
+"-s") tracetos ;;
 "--check-backend") exit 0 ;; # used by ./configure to test for backend
 *) usage ;;
 esac
-- 
1.7.2.3

Re: [Qemu-devel] [PATCH 1/2] Add a DTrace tracing backend targetted for SystemTAP compatability

[Stefan Hajnoczi]

On Mon, Nov 8, 2010 at 11:33 AM, Daniel P. Berrange <dan@berrange.com> wrote:
> diff --git a/Makefile b/Makefile
> index 02698e9..384bf72 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1,6 +1,10 @@
>  # Makefile for QEMU.
>
>  GENERATED_HEADERS = config-host.h trace.h qemu-options.def
> +GENERATED_HEADERS = config-host.h trace.h
> +ifeq ($(TRACE_BACKEND),dtrace)
> +GENERATED_HEADERS += trace-dtrace.h
> +endif

What happened to qemu-options.def?  GENERATED_HEADERS is defined
twice, the first line should probably be deleted.

Looks good otherwise.

Stefan

Re: [Qemu-devel] [PATCH 1/2] Add a DTrace tracing backend targetted for SystemTAP compatability

[Daniel P. Berrange]

On Mon, Nov 08, 2010 at 04:52:01PM +0000, Stefan Hajnoczi wrote:
> On Mon, Nov 8, 2010 at 11:33 AM, Daniel P. Berrange <dan@berrange.com> wrote:
> > diff --git a/Makefile b/Makefile
> > index 02698e9..384bf72 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -1,6 +1,10 @@
> >  # Makefile for QEMU.
> >
> >  GENERATED_HEADERS = config-host.h trace.h qemu-options.def
> > +GENERATED_HEADERS = config-host.h trace.h
> > +ifeq ($(TRACE_BACKEND),dtrace)
> > +GENERATED_HEADERS += trace-dtrace.h
> > +endif
> 
> What happened to qemu-options.def?  GENERATED_HEADERS is defined
> twice, the first line should probably be deleted.

Oh, the loss of qemu-options.def is a rebase/merge error. GENERATED_HEADERS
isn't defined twice, because the second line is using += to append to the
first definition.

Regards,
Daniel
-- 
|: Red Hat, Engineering, London    -o-   http://people.redhat.com/berrange/ :|
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Re: [Qemu-devel] [PATCH 1/2] Add a DTrace tracing backend targetted for SystemTAP compatability

[Stefan Hajnoczi]

On Mon, Nov 8, 2010 at 4:57 PM, Daniel P. Berrange <berrange@redhat.com> wrote:
> On Mon, Nov 08, 2010 at 04:52:01PM +0000, Stefan Hajnoczi wrote:
>> On Mon, Nov 8, 2010 at 11:33 AM, Daniel P. Berrange <dan@berrange.com> wrote:
>> > diff --git a/Makefile b/Makefile
>> > index 02698e9..384bf72 100644
>> > --- a/Makefile
>> > +++ b/Makefile
>> > @@ -1,6 +1,10 @@
>> >  # Makefile for QEMU.
>> >
>> >  GENERATED_HEADERS = config-host.h trace.h qemu-options.def
>> > +GENERATED_HEADERS = config-host.h trace.h
>> > +ifeq ($(TRACE_BACKEND),dtrace)
>> > +GENERATED_HEADERS += trace-dtrace.h
>> > +endif
>>
>> What happened to qemu-options.def?  GENERATED_HEADERS is defined
>> twice, the first line should probably be deleted.
>
> Oh, the loss of qemu-options.def is a rebase/merge error. GENERATED_HEADERS
> isn't defined twice, because the second line is using += to append to the
> first definition.

Ah, it's the merge error I was referring to:

 @@ -1,6 +1,10 @@
 # Makefile for QEMU.

 GENERATED_HEADERS = config-host.h trace.h qemu-options.def
+GENERATED_HEADERS = config-host.h trace.h

Stefan

Re: [Qemu-devel] [PATCH 2/2] Add support for generating a systemtap tapset static probes

[Stefan Hajnoczi]

On Mon, Nov 8, 2010 at 11:33 AM, Daniel P. Berrange <dan@berrange.com> wrote:
> @@ -390,6 +396,54 @@ linetod_end_dtrace()
>  EOF
>  }
>
> +linetos_begin_dtrace()
> +{
> +    return
> +}
> +
> +linetos_dtrace()
> +{
> +    local name args arglist state

Missing binary, i, and arg.

> +    name=$(get_name "$1")
> +    args=$(get_args "$1")
> +    arglist=$(get_argnames "$1", "")
> +    state=$(get_state "$1")
> +    if [ "$state" = "0" ] ; then
> +        name=${name##disable }
> +    fi
> +
> +    if [ "$target" = "i386" ]
> +    then
> +      binary="qemu"
> +    else
> +      binary="qemu-system-$target"
> +    fi

Perhaps we should just pass in the binary name to avoid hardcoding "qemu" and
"qemu-system-$target" here.  If possible, let's make SystemTap also work for
userspace targets, not just for full-system softmmu targets.

> +
> +    # Define prototype for probe arguments
> +    cat <<EOF
> +probe qemu.system.$target.$name = process("$bindir/$binary").mark("$name")
> +{
> +EOF
> +
> +    i=1
> +    for arg in $arglist
> +    do
> +        cat <<EOF
> +  $arg = \$arg$i;
> +EOF
> +       i="$((i+1))"
> +    done
> +
> +    cat <<EOF
> +}
> +EOF
> +}
> +
> +linetos_end_dtrace()
> +{
> +    return
> +}
> +
>  # Process stdin by calling begin, line, and end functions for the backend
>  convert()
>  {
> @@ -455,6 +509,24 @@ tracetod()
>     convert d
>  }
>
> +tracetos()

How about using 'stap' instead of 's' so it's clear we're not generating
assembly?

Stefan