On Mon, 15 Mar 2021 11:52:13 +0100
Thomas Monjalon [off-list ref] wrote:

15/03/2021 11:42, Kinsella, Ray:

quoted

On 15/03/2021 10:31, Bruce Richardson wrote:  

quoted

On Mon, Mar 15, 2021 at 10:19:47AM +0000, Kinsella, Ray wrote:  

quoted

On 12/03/2021 18:17, Thomas Monjalon wrote:  

quoted

The option --log-level was not completely described in the usage text,
and it was difficult to guess the names of the log types and levels.

A new value "help" is accepted after --log-level to give more details
about the syntax and listing the log types and levels.

The array "levels" used for level name parsing is replaced with
a (modified) existing function which was used in rte_log_dump().

The new function rte_log_list_types() is exported in the API
for allowing an application to give this info to the user
if not exposing the EAL option --log-level.
The list of log types cannot include all drivers if not linked in the
application (shared object plugin case).

Signed-off-by: Thomas Monjalon <redacted>
---
 lib/librte_eal/common/eal_common_log.c     | 24 +++++++++---
 lib/librte_eal/common/eal_common_options.c | 44 +++++++++++++++-------
 lib/librte_eal/common/eal_log.h            |  5 +++
 lib/librte_eal/include/rte_log.h           | 11 ++++++
 lib/librte_eal/version.map                 |  3 ++
 5 files changed, 69 insertions(+), 18 deletions(-)
 

<snip>  

quoted

quoted

@@ -1274,6 +1286,11 @@ eal_parse_log_level(const char *arg)
 	char *str, *level;
 	int priority;
 
+	if (strcmp(arg, "help") == 0) {  

So I think the convention is to support both "?" and "help".
Qemu does this at least. 
 

I've seen "/?" used for help on windows binaries, but "-?" not so much in the
linux world, where --help (and often -h for short) seem to be the standard.
  

This is slightly different - it is where you are looking to return a list of valid 
values for a parameter. So for instance in qemu mentioned above 

 ~ > qemu-system-x86_64 -cpu ? | head -n 10  

"?" is a special character.
In my zsh, I need to quote it to avoid globbing parsing,
so I'm not a fan.

I will let you extend the syntax in a separate patch :)

Also '?' is used by getopt to match unknown option. So qemu might just be
doing that as unintended side effect of any unknown option