[PATCH v2] vl: Print display options for -display help

[Akihiko Odaki]

-display lists display backends, but does not tell their options.
Use the help messages from qemu-options.def, which include the list of
options.

Note that this change also has an unfortunate side effect that it will
no longer tell what UI modules are actually available.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
Changes in v2:
- Noted that it no longer tells the availability of UI modules.
  (Marc-André Lureau)
- Link to v1: 
20231214-help-v1-1-23823ac5a023@daynix.com">https://lore.kernel.org/r/20231214-help-v1-1-23823ac5a023@daynix.com
---
 include/ui/console.h |  1 -
 system/vl.c          | 11 ++++++-----
 ui/console.c         | 20 --------------------
 3 files changed, 6 insertions(+), 26 deletions(-)

diff --git a/include/ui/console.h b/include/ui/console.h
index a4a49ffc640c..58f757350647 100644
--- a/include/ui/console.h
+++ b/include/ui/console.h
@@ -470,7 +470,6 @@ bool qemu_display_find_default(DisplayOptions *opts);
 void qemu_display_early_init(DisplayOptions *opts);
 void qemu_display_init(DisplayState *ds, DisplayOptions *opts);
 const char *qemu_display_get_vc(DisplayOptions *opts);
-void qemu_display_help(void);
 
 /* vnc.c */
 void vnc_display_init(const char *id, Error **errp);
diff --git a/system/vl.c b/system/vl.c
index 2bcd9efb9a64..f9656667ee54 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -915,16 +915,17 @@ enum {
 
 typedef struct QEMUOption {
     const char *name;
+    const char *help;
     int flags;
     int index;
     uint32_t arch_mask;
 } QEMUOption;
 
 static const QEMUOption qemu_options[] = {
-    { "h", 0, QEMU_OPTION_h, QEMU_ARCH_ALL },
+    { "h", NULL, 0, QEMU_OPTION_h, QEMU_ARCH_ALL },
 
 #define DEF(option, opt_arg, opt_enum, opt_help, arch_mask)     \
-    { option, opt_arg, opt_enum, arch_mask },
+    { option, opt_help, opt_arg, opt_enum, arch_mask },
 #define DEFHEADING(text)
 #define ARCHHEADING(text, arch_mask)
 
@@ -1094,10 +1095,10 @@ DisplayOptions *qmp_query_display_options(Error **errp)
     return QAPI_CLONE(DisplayOptions, &dpy);
 }
 
-static void parse_display(const char *p)
+static void parse_display(const char *p, const char *help)
 {
     if (is_help_option(p)) {
-        qemu_display_help();
+        fputs(help, stdout);
         exit(0);
     }
 
@@ -2880,7 +2881,7 @@ void qemu_init(int argc, char **argv)
                 }
                 break;
             case QEMU_OPTION_display:
-                parse_display(optarg);
+                parse_display(optarg, popt->help);
                 break;
             case QEMU_OPTION_nographic:
                 qdict_put_str(machine_opts_dict, "graphics", "off");
diff --git a/ui/console.c b/ui/console.c
index 7db921e3b7d6..6aee5e9a7ffb 100644
--- a/ui/console.c
+++ b/ui/console.c
@@ -1691,23 +1691,3 @@ const char *qemu_display_get_vc(DisplayOptions *opts)
     }
     return vc;
 }
-
-void qemu_display_help(void)
-{
-    int idx;
-
-    printf("Available display backend types:\n");
-    printf("none\n");
-    for (idx = DISPLAY_TYPE_NONE; idx < DISPLAY_TYPE__MAX; idx++) {
-        if (!dpys[idx]) {
-            Error *local_err = NULL;
-            int rv = ui_module_load(DisplayType_str(idx), &local_err);
-            if (rv < 0) {
-                error_report_err(local_err);
-            }
-        }
-        if (dpys[idx]) {
-            printf("%s\n",  DisplayType_str(dpys[idx]->type));
-        }
-    }
-}

---
base-commit: 4705fc0c8511d073bee4751c3c974aab2b10a970
change-id: 20231214-help-9fa146fc6e95

Best regards,
-- 
Akihiko Odaki <akihiko.odaki@daynix.com>