On 14/09/2026 11.00, Thomas Huth wrote:
Other command line options like "-chardev", "-netdev" or "-device"
already present the user with a list of available parameters, but
when running "-blockdev help", there is currently only an error
message. There is already the possibility to run "-drive format=help",
but it does not seem to be documented, so this is not very useful
for the average user. Thus let's improve this situation by providing
a proper list of available drivers when running QEMU with
"-blockdev help".
Signed-off-by: Thomas Huth <[email protected]>
---
v2: Don't re-use the code from "-drive format=help" and print the
help in a better readable way instead
Ping?
include/block/block-common.h | 1 +
block.c | 15 +++++++++++++++
system/vl.c | 7 +++++--
3 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/include/block/block-common.h b/include/block/block-common.h
index 895ea175413..c76a72c1220 100644
--- a/include/block/block-common.h
+++ b/include/block/block-common.h
@@ -583,5 +583,6 @@ char *path_combine(const char *base_path, const char
*filename);
char *bdrv_get_full_backing_filename_from_filename(const char *backed,
const char *backing,
Error **errp);
+void bdrv_show_help(void);
#endif /* BLOCK_COMMON_H */
diff --git a/block.c b/block.c
index f0a6042e616..895d6db5acf 100644
--- a/block.c
+++ b/block.c
@@ -524,6 +524,21 @@ bool bdrv_uses_whitelist(void)
return use_bdrv_whitelist;
}
+static void bdrv_help_format_print(void *opaque, const char *name)
+{
+ if (bdrv_format_is_whitelisted(name, false)) {
+ printf("%s\n", name);
+ } else {
+ printf("%s (read-only)\n", name);
+ }
+}
+
+void bdrv_show_help(void)
+{
+ printf("Available blockdev drivers:\n");
+ bdrv_iterate_format(bdrv_help_format_print, NULL, true);
+}
+
typedef struct CreateCo {
BlockDriver *drv;
char *filename;
diff --git a/system/vl.c b/system/vl.c
index 9bd7664b85c..dc93e8737cb 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -2960,7 +2960,10 @@ void qemu_init(int argc, char **argv)
HD_OPTS);
break;
case QEMU_OPTION_blockdev:
- {
+ if (is_help_option(optarg)) {
+ bdrv_show_help();
+ exit(EXIT_SUCCESS);
+ } else {
Visitor *v;
BlockdevOptionsQueueEntry *bdo;
@@ -2973,8 +2976,8 @@ void qemu_init(int argc, char **argv)
visit_free(v);
loc_save(&bdo->loc);
QSIMPLEQ_INSERT_TAIL(&bdo_queue, bdo, entry);
- break;
}
+ break;
case QEMU_OPTION_drive:
if (!qemu_opts_parse_noisily(qemu_find_opts("drive"),
optarg, false)) {
