Re: [PATCH v3] ui: Print available display backends with '-display help'

[Thomas Huth <thuth@redhat.com>]

On 20/01/2020 01.01, Philippe Mathieu-Daudé wrote:
> Hi Thomas,
> 
> On 1/8/20 3:47 PM, Thomas Huth wrote:
>> We already print availabled devices with "-device help", or available
>> backends with "-netdev help" or "-chardev help". Let's provide a way
>> for the users to query the available display backends, too.
>>
>> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>  v3: Mention -display help in the qemu-doc, too (as suggested by Philippe)
>>
>>  include/ui/console.h |  1 +
>>  qemu-options.hx      |  3 ++-
>>  ui/console.c         | 15 +++++++++++++++
>>  vl.c                 |  5 +++++
>>  4 files changed, 23 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/ui/console.h b/include/ui/console.h
>> index 281f9c145b..f35b4fc082 100644
>> --- a/include/ui/console.h
>> +++ b/include/ui/console.h
>> @@ -442,6 +442,7 @@ void qemu_display_register(QemuDisplay *ui);
>>  bool qemu_display_find_default(DisplayOptions *opts);
>>  void qemu_display_early_init(DisplayOptions *opts);
>>  void qemu_display_init(DisplayState *ds, DisplayOptions *opts);
>> +void qemu_display_help(void);
>>  
>>  /* vnc.c */
>>  void vnc_display_init(const char *id, Error **errp);
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index e9d6231438..d593931664 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -1586,7 +1586,8 @@ STEXI
>>  @item -display @var{type}
>>  @findex -display
>>  Select type of display to use. This option is a replacement for the
>> -old style -sdl/-curses/... options. Valid values for @var{type} are
>> +old style -sdl/-curses/... options. Use @code{-display help} to list
>> +the available display types. Valid values for @var{type} are
>>  @table @option
>>  @item sdl
>>  Display video output via SDL (usually in a separate graphics
>> diff --git a/ui/console.c b/ui/console.c
>> index ac79d679f5..69339b028b 100644
>> --- a/ui/console.c
>> +++ b/ui/console.c
>> @@ -2333,6 +2333,21 @@ void qemu_display_init(DisplayState *ds, DisplayOptions *opts)
>>      dpys[opts->type]->init(ds, opts);
>>  }
>>  
>> +void qemu_display_help(void)
>> +{
>> +    int idx;
>> +
>> +    printf("Available display backend types:\n");
>> +    for (idx = DISPLAY_TYPE_NONE; idx < DISPLAY_TYPE__MAX; idx++) {
>> +        if (!dpys[idx]) {
>> +            ui_module_load_one(DisplayType_str(idx));
>> +        }
>> +        if (dpys[idx]) {
>> +            printf("%s\n",  DisplayType_str(dpys[idx]->type));
> 
> While listed in the man page, the "none" display is not listed here, any
> clue?

I assume we'd need to print it out manually here since there is no
implementation for this in the dpys array. Care to send a patch?

 Thomas