trace: Add trace file name command-line option

This patch adds an optional command line switch '-trace' to specify the
filename to write traces to, when qemu starts.
Eg, If compiled with the 'simple' trace backend,
[temp@system]$ qemu -trace FILENAME IMAGE
Allows the binary traces to be written to FILENAME instead of the option
set at config-time.

Signed-off-by: Prerna Saxena <prerna@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

3 files changed, 50 insertions, 0 deletions

diff --git a/qemu-config.c b/qemu-config.c
index 1efdbecdad..e3b746cc2b 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -288,6 +288,21 @@ static QemuOptsList qemu_mon_opts = {
     },
 };
 
+#ifdef CONFIG_SIMPLE_TRACE
+static QemuOptsList qemu_trace_opts = {
+    .name = "trace",
+    .implied_opt_name = "trace",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_trace_opts.head),
+    .desc = {
+        {
+            .name = "file",
+            .type = QEMU_OPT_STRING,
+        },
+        { /* end if list */ }
+    },
+};
+#endif
+
 static QemuOptsList qemu_cpudef_opts = {
     .name = "cpudef",
     .head = QTAILQ_HEAD_INITIALIZER(qemu_cpudef_opts.head),
@@ -346,6 +361,9 @@ static QemuOptsList *vm_config_groups[32] = {
     &qemu_global_opts,
     &qemu_mon_opts,
     &qemu_cpudef_opts,
+#ifdef CONFIG_SIMPLE_TRACE
+    &qemu_trace_opts,
+#endif
     NULL,
 };
 
diff --git a/qemu-options.hx b/qemu-options.hx
index 368bf964a8..a0b5ae9bf1 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2230,6 +2230,17 @@ Normally QEMU loads a configuration file from @var{sysconfdir}/qemu.conf and
 @var{sysconfdir}/target-@var{ARCH}.conf on startup.  The @code{-nodefconfig}
 option will prevent QEMU from loading these configuration files at startup.
 ETEXI
+#ifdef CONFIG_SIMPLE_TRACE
+DEF("trace", HAS_ARG, QEMU_OPTION_trace,
+    "-trace\n"
+    "                Specify a trace file to log traces to\n",
+    QEMU_ARCH_ALL)
+STEXI
+@item -trace
+@findex -trace
+Specify a trace file to log output traces to.
+ETEXI
+#endif
 
 HXCOMM This is the last statement. Insert new options before this line!
 STEXI
diff --git a/vl.c b/vl.c
index df11ab309f..3f45aa90fc 100644
--- a/vl.c
+++ b/vl.c
@@ -47,6 +47,10 @@
 #include <dirent.h>
 #include <netdb.h>
 #include <sys/select.h>
+#ifdef CONFIG_SIMPLE_TRACE
+#include "trace.h"
+#endif
+
 #ifdef CONFIG_BSD
 #include <sys/stat.h>
 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
@@ -1823,6 +1827,9 @@ int main(int argc, char **argv, char **envp)
     int show_vnc_port = 0;
     int defconfig = 1;
 
+#ifdef CONFIG_SIMPLE_TRACE
+    const char *trace_file = NULL;
+#endif
     atexit(qemu_run_exit_notifiers);
     error_set_progname(argv[0]);
 
@@ -2595,6 +2602,14 @@ int main(int argc, char **argv, char **envp)
                 }
                 xen_mode = XEN_ATTACH;
                 break;
+#ifdef CONFIG_SIMPLE_TRACE
+            case QEMU_OPTION_trace:
+                opts = qemu_opts_parse(qemu_find_opts("trace"), optarg, 0);
+                if (opts) {
+                    trace_file = qemu_opt_get(opts, "file");
+                }
+                break;
+#endif
             case QEMU_OPTION_readconfig:
                 {
                     int ret = qemu_read_config_file(optarg);
@@ -2638,6 +2653,12 @@ int main(int argc, char **argv, char **envp)
         data_dir = CONFIG_QEMU_DATADIR;
     }
 
+#ifdef CONFIG_SIMPLE_TRACE
+    /*
+     * Set the trace file name, if specified.
+     */
+    st_set_trace_file(trace_file);
+#endif
     /*
      * Default to max_cpus = smp_cpus, in case the user doesn't
      * specify a max_cpus value.