The 'gen_id' argument refers to a QOM object able to produce
data consumable by the fw_cfg device. The producer object must
implement the FW_CFG_DATA_GENERATOR interface.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
v8: addressed Laszlo's comments
- fixed 2-space indent
- do not return 0 on failure
---
 softmmu/vl.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/softmmu/vl.c b/softmmu/vl.c
index 05d1a4cb6b..a9bce2a1b1 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -489,6 +489,11 @@ static QemuOptsList qemu_fw_cfg_opts = {
             .name = "string",
             .type = QEMU_OPT_STRING,
             .help = "Sets content of the blob to be inserted from a string",
+        }, {
+            .name = "gen_id",
+            .type = QEMU_OPT_STRING,
+            .help = "Sets id of the object generating the fw_cfg blob "
+                    "to be inserted",
         },
         { /* end of list */ }
     },
@@ -2020,7 +2025,7 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp)
 {
     gchar *buf;
     size_t size;
-    const char *name, *file, *str;
+    const char *name, *file, *str, *gen_id;
     FWCfgState *fw_cfg = (FWCfgState *) opaque;
 
     if (fw_cfg == NULL) {
@@ -2030,14 +2035,13 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp)
     name = qemu_opt_get(opts, "name");
     file = qemu_opt_get(opts, "file");
     str = qemu_opt_get(opts, "string");
+    gen_id = qemu_opt_get(opts, "gen_id");
 
-    /* we need name and either a file or the content string */
-    if (!(nonempty_str(name) && (nonempty_str(file) || nonempty_str(str)))) {
-        error_setg(errp, "invalid argument(s)");
-        return -1;
-    }
-    if (nonempty_str(file) && nonempty_str(str)) {
-        error_setg(errp, "file and string are mutually exclusive");
+    /* we need the name, and exactly one of: file, content string, gen_id */
+    if (!nonempty_str(name) ||
+        nonempty_str(file) + nonempty_str(str) + nonempty_str(gen_id) != 1) {
+        error_setg(errp, "name, plus exactly one of file,"
+                         " string and gen_id, are needed");
         return -1;
     }
     if (strlen(name) > FW_CFG_MAX_FILE_PATH - 1) {
@@ -2052,6 +2056,11 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp)
     if (nonempty_str(str)) {
         size = strlen(str); /* NUL terminator NOT included in fw_cfg blob */
         buf = g_memdup(str, size);
+    } else if (nonempty_str(gen_id)) {
+        size_t fw_cfg_size;
+
+        fw_cfg_size = fw_cfg_add_from_generator(fw_cfg, name, gen_id, errp);
+        return (fw_cfg_size > 0) ? 0 : -1;
     } else {
         GError *err = NULL;
         if (!g_file_get_contents(file, &buf, &size, &err)) {
-- 
2.21.3

On 06/09/20 19:07, Philippe Mathieu-Daudé wrote:
> The 'gen_id' argument refers to a QOM object able to produce
> data consumable by the fw_cfg device. The producer object must
> implement the FW_CFG_DATA_GENERATOR interface.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> v8: addressed Laszlo's comments
> - fixed 2-space indent
> - do not return 0 on failure
> ---
>  softmmu/vl.c | 25 +++++++++++++++++--------
>  1 file changed, 17 insertions(+), 8 deletions(-)
> 
> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index 05d1a4cb6b..a9bce2a1b1 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -489,6 +489,11 @@ static QemuOptsList qemu_fw_cfg_opts = {
>              .name = "string",
>              .type = QEMU_OPT_STRING,
>              .help = "Sets content of the blob to be inserted from a string",
> +        }, {
> +            .name = "gen_id",
> +            .type = QEMU_OPT_STRING,
> +            .help = "Sets id of the object generating the fw_cfg blob "
> +                    "to be inserted",
>          },
>          { /* end of list */ }
>      },
> @@ -2020,7 +2025,7 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp)
>  {
>      gchar *buf;
>      size_t size;
> -    const char *name, *file, *str;
> +    const char *name, *file, *str, *gen_id;
>      FWCfgState *fw_cfg = (FWCfgState *) opaque;
>  
>      if (fw_cfg == NULL) {
> @@ -2030,14 +2035,13 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp)
>      name = qemu_opt_get(opts, "name");
>      file = qemu_opt_get(opts, "file");
>      str = qemu_opt_get(opts, "string");
> +    gen_id = qemu_opt_get(opts, "gen_id");
>  
> -    /* we need name and either a file or the content string */
> -    if (!(nonempty_str(name) && (nonempty_str(file) || nonempty_str(str)))) {
> -        error_setg(errp, "invalid argument(s)");
> -        return -1;
> -    }
> -    if (nonempty_str(file) && nonempty_str(str)) {
> -        error_setg(errp, "file and string are mutually exclusive");
> +    /* we need the name, and exactly one of: file, content string, gen_id */
> +    if (!nonempty_str(name) ||
> +        nonempty_str(file) + nonempty_str(str) + nonempty_str(gen_id) != 1) {
> +        error_setg(errp, "name, plus exactly one of file,"
> +                         " string and gen_id, are needed");
>          return -1;
>      }
>      if (strlen(name) > FW_CFG_MAX_FILE_PATH - 1) {
> @@ -2052,6 +2056,11 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp)
>      if (nonempty_str(str)) {
>          size = strlen(str); /* NUL terminator NOT included in fw_cfg blob */
>          buf = g_memdup(str, size);
> +    } else if (nonempty_str(gen_id)) {
> +        size_t fw_cfg_size;
> +
> +        fw_cfg_size = fw_cfg_add_from_generator(fw_cfg, name, gen_id, errp);
> +        return (fw_cfg_size > 0) ? 0 : -1;
>      } else {
>          GError *err = NULL;
>          if (!g_file_get_contents(file, &buf, &size, &err)) {
> 

Reviewed-by: Laszlo Ersek <lersek@redhat.com>