Re: [PATCH v2 21/35] xen/console: introduce console_init_owner()

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Dec 05, 2024 at 08:41:51PM -0800, Denis Mukhin via B4 Relay wrote:
> From: Denis Mukhin <dmukhin@xxxxxxxx>
> 
> console_init_owner() is introduced for selecting the boot-time console owner.
> 
> Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
> ---
>  xen/drivers/char/console.c | 27 +++++++++++++++++----------
>  1 file changed, 17 insertions(+), 10 deletions(-)
> 
> diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
> index 
> a8ab5c2bcb98e4cadf9ad2c9ad28d297977d0557..6261bdb5a2ac1075bc89fa408c0fd6cfef380ae6
>  100644
> --- a/xen/drivers/char/console.c
> +++ b/xen/drivers/char/console.c
> @@ -554,6 +554,22 @@ static void console_find_owner(void)
>          console_set_owner(DOMID_XEN);
>  }
>  
> +static void console_init_owner(void)

__init attribute missing (given current call context), but see below.

> +{
> +    domid_t domid;
> +
> +    /*
> +     * If user specifies so, we fool the switch routine to redirect input
> +     * straight back to Xen.
> +     */
> +    if ( opt_conswitch[1] == 'x' )
> +        domid = DOMID_XEN;
> +    else
> +        domid = get_initial_domain_id();
> +
> +    console_set_owner(domid);
> +}
> +
>  static void __serial_rx(char c)
>  {
>      switch ( console_owner )
> @@ -1143,14 +1159,6 @@ void __init console_endboot(void)
>  
>      video_endboot();
>  
> -    /*
> -     * If user specifies so, we fool the switch routine to redirect input
> -     * straight back to Xen. I use this convoluted method so we still print
> -     * a useful 'how to switch' message.
> -     */
> -    if ( opt_conswitch[1] == 'x' )
> -        console_owner = DOMID_XEN;
> -
>      register_keyhandler('w', dump_console_ring_key,
>                          "synchronously dump console ring buffer (dmesg)", 0);
>      register_irq_keyhandler('+', &do_inc_thresh,
> @@ -1160,8 +1168,7 @@ void __init console_endboot(void)
>      register_irq_keyhandler('G', &do_toggle_guest,
>                              "toggle host/guest log level adjustment", 0);
>  
> -    /* Serial input is directed to DOM0 by default. */
> -    console_find_owner();
> +    console_init_owner();

Oh, so this is what fixes the regression introduced in patch 19/35.
THB I'm not sure it's worth introducing the console_init_owner()
helper if it's just for this usage.  You could do:

console_set_owner(opt_conswitch[1] == 'x' ? DOMID_XEN
                                          : get_initial_domain_id());

Thanks, Roger.