[Qemu-devel] [PATCH v4 02/10] trace: avoid conditional code compilation during option parsing

[Lluís <xscript@gmx.net>]

Instead of conditionally compiling option support, perform checks and issue the
corresponding error messages.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
---
 configure       |    4 +++-
 qemu-config.c   |    4 ----
 qemu-options.hx |    6 ++++--
 vl.c            |   17 +++++++++++++----
 4 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/configure b/configure
index 6f75e2e..fef7d35 100755
--- a/configure
+++ b/configure
@@ -2945,7 +2945,9 @@ bsd)
 esac
 
 echo "TRACE_BACKEND=$trace_backend" >> $config_host_mak
-if test "$trace_backend" = "simple"; then
+if test "$trace_backend" = "nop"; then
+  echo "CONFIG_TRACE_NOP=y" >> $config_host_mak
+elif test "$trace_backend" = "simple"; then
   echo "CONFIG_SIMPLE_TRACE=y" >> $config_host_mak
 fi
 # Set the appropriate trace file.
diff --git a/qemu-config.c b/qemu-config.c
index 14d3419..db5b14c 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -296,7 +296,6 @@ static QemuOptsList qemu_mon_opts = {
     },
 };
 
-#ifdef CONFIG_SIMPLE_TRACE
 static QemuOptsList qemu_trace_opts = {
     .name = "trace",
     .implied_opt_name = "trace",
@@ -309,7 +308,6 @@ static QemuOptsList qemu_trace_opts = {
         { /* end if list */ }
     },
 };
-#endif
 
 static QemuOptsList qemu_cpudef_opts = {
     .name = "cpudef",
@@ -460,9 +458,7 @@ static QemuOptsList *vm_config_groups[32] = {
     &qemu_global_opts,
     &qemu_mon_opts,
     &qemu_cpudef_opts,
-#ifdef CONFIG_SIMPLE_TRACE
     &qemu_trace_opts,
-#endif
     &qemu_option_rom_opts,
     NULL,
 };
diff --git a/qemu-options.hx b/qemu-options.hx
index 489df10..b439120 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2356,17 +2356,19 @@ 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
+HXCOMM This line is not accurate, as the option is backend-specific but HX does
+HXCOMM not support conditional compilation of text.
 @item -trace
 @findex -trace
 Specify a trace file to log output traces to.
+
+This option is available only when using the @var{simple} tracing backend.
 ETEXI
-#endif
 
 HXCOMM This is the last statement. Insert new options before this line!
 STEXI
diff --git a/vl.c b/vl.c
index 3eac0bc..9db7b64 100644
--- a/vl.c
+++ b/vl.c
@@ -2744,14 +2744,23 @@ 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");
+                if (!opts) {
+                    exit(1);
                 }
-                break;
+#if defined(CONFIG_TRACE_NOP)
+                fprintf(stderr, "qemu: option \"-%s\" is not supported by this tracing backend\n", popt->name);
+                exit(1);
 #endif
+                trace_file = qemu_opt_get(opts, "file");
+#if !defined(CONFIG_SIMPLE_TRACE)
+                if (trace_file) {
+                    fprintf(stderr, "qemu: suboption \"-%s file\" is not supported by this tracing backend\n", popt->name);
+                    exit(1);
+                }
+#endif
+                break;
             case QEMU_OPTION_readconfig:
                 {
                     int ret = qemu_read_config_file(optarg);