Re: [Xen-devel] [PATCH v4 20/23] xen: support console_switching between Dom0 and DomUs on ARM

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.10.18 at 20:47, <sstabellini@xxxxxxxxxx> wrote:
> @@ -391,31 +394,73 @@ static void dump_console_ring_key(unsigned char key)
>      free_xenheap_pages(buf, order);
>  }
>  
> -/* CTRL-<switch_char> switches input direction between Xen and DOM0. */
> +/*
> + * CTRL-<switch_char> switches input direction between Xen, Dom0 and
> + * DomUs.
> + */

Just like the title, this comment makes it sound as if any DomU could
participate in this switching.

>  #define switch_code (opt_conswitch[0]-'a'+1)
> -static int __read_mostly xen_rx = 1; /* FALSE => input passed to domain 0. */
> +/*
> + * console_rx=0 => input to xen
> + * console_rx=1 => input to dom0
> + * console_rx=N => input dom(N-1)
> + */
> +static unsigned int __read_mostly console_rx = 0;
>  
>  static void switch_serial_input(void)
>  {
> -    static char *input_str[2] = { "DOM0", "Xen" };
> -    xen_rx = !xen_rx;
> -    printk("*** Serial input -> %s", input_str[xen_rx]);
> +    if ( console_rx++ == max_init_domid + 1 )
> +        console_rx = 0;
> +
> +    if ( !console_rx )

Please be consistent ...

> +        printk("*** Serial input to Xen");
> +    else
> +        printk("*** Serial input to DOM%d", console_rx - 1);
> +
>      if ( switch_code )
> -        printk(" (type 'CTRL-%c' three times to switch input to %s)",
> -               opt_conswitch[0], input_str[!xen_rx]);
> +        printk(" (type 'CTRL-%c' three times to switch input)",
> +               opt_conswitch[0]);
>      printk("\n");
>  }
>  
>  static void __serial_rx(char c, struct cpu_user_regs *regs)
>  {
> -    if ( xen_rx )
> +    if ( console_rx == 0 )

... in style. But perhaps ...

>          return handle_keypress(c, regs);
>  
> -    /* Deliver input to guest buffer, unless it is already full. */
> -    if ( (serial_rx_prod-serial_rx_cons) != SERIAL_RX_SIZE )
> -        serial_rx_ring[SERIAL_RX_MASK(serial_rx_prod++)] = c;
> -    /* Always notify the guest: prevents receive path from getting stuck. */
> -    send_global_virq(VIRQ_CONSOLE);
> +    if ( console_rx == 1 )

... switch() would be better to use here anyway.

> +    {
> +        /* Deliver input to hardware domain, unless it is already full. */

Looks like you've mis-edited the original comment.

Jan



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