Re: [PATCH v2 19/35] xen/console: introduce console_set_owner()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.12.2024 05:41, Denis Mukhin via B4 Relay wrote:
> --- a/xen/drivers/char/console.c
> +++ b/xen/drivers/char/console.c
> @@ -463,82 +463,100 @@ static void cf_check dump_console_ring_key(unsigned 
> char key)
>  
>  /*
>   * CTRL-<switch_char> changes input direction, rotating among Xen, Dom0,
> - * and the DomUs started from Xen at boot.
> + * and the DomUs.
>   */
>  #define switch_code (opt_conswitch[0]-'a'+1)
> +
>  /*
> - * console_owner=0 => input to xen
> - * console_owner=1 => input to dom0 (or the sole shim domain)
> - * console_owner=N => input to dom(N-1)
> + * Current console owner domain ID: either Xen or domain w/ d->is_console ==
> + * true.

The switching of number space may better have been a separate patch.
Albeit maybe I'm just not seeing why it wants combining with the
introduction of console_set_owner().

Actually, is this switching actually complete? What about late hwdom,
which has a non-zero domain ID?

> + * Initialized in console_endboot().
>   */
> -static unsigned int __read_mostly console_owner = 0;
> +static domid_t __read_mostly console_owner;
>  
> -#define max_console_rx (max_init_domid + 1)
> +static struct domain *rcu_lock_domain_console_by_id(domid_t domid)

I think "domain" and "console" want switching in the name, as it's a
domain you're locking, not a console.

> +int console_set_owner(domid_t domid)

static? Iirc Misra doesn't like non-static functions which aren't called
from any other CU.

Jan