Re: [PATCH] ui/console: Display the 'none' backend in '-display help'

[Eric Blake]

On 1/20/20 1:29 PM, Philippe Mathieu-Daudé wrote:
> Commit c388f408b5 added the possibility to list the display
> backends using '-display help'. Since the 'none' backend is
> is not implemented as a DisplayChangeListenerOps, it is not
> registered to the dpys[] array with qemu_display_register(),
> and is not listed in the help output.
>
> This might be confusing, as we list it in the man page:
>
>    -display type
>        Select type of display to use. This option is a replacement for
>        the old style -sdl/-curses/... options. Valid values for type are
>
>        none
>            Do not display video output. The guest will still see an
>            emulated graphics card, but its output will not be displayed
>            to the QEMU user. This option differs from the -nographic
>            option in that it only affects what is done with video
>            output; -nographic also changes the destination of the serial
>            and parallel port data.
>
> Fix by manually listing the special 'none' backend in the help.
>
> Suggested-by: Thomas Huth <address@hidden>
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
>   ui/console.c | 1 +
>   1 file changed, 1 insertion(+)

Reviewed-by: Eric Blake <address@hidden>

> diff --git a/ui/console.c b/ui/console.c
> index 69339b028b..179901c35e 100644
> --- a/ui/console.c
> +++ b/ui/console.c
> @@ -2338,6 +2338,7 @@ 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]) {
>               ui_module_load_one(DisplayType_str(idx));

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org