Re: [Xen-devel] [PATCH] console: allocate ring buffer earlier

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Fri, Dec 05, 2014 at 04:55:24PM +0000, Jan Beulich wrote:
> ... when "conring_size=" was specified on the command line. We can't
> really do this as early as we would want to when the option was not
> specified, as the default depends on knowing the system CPU count. Yet
> the parsing of the ACPI tables is one of the things that generates a
> lot of output especially on large systems.
>
> I didn't change ARM, as I wasn't sure how far ahead this call could be
> pulled.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Make sense for me but I think that we should have the same thing for ARM too.

> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -1187,6 +1187,7 @@ void __init noreturn __start_xen(unsigne
>      }
>
>      vm_init();
> +    console_init_mem();
>      vesa_init();
>
>      softirq_init();
> --- a/xen/drivers/char/console.c
> +++ b/xen/drivers/char/console.c
> @@ -744,15 +744,14 @@ void __init console_init_preirq(void)
>      }
>  }
>
> -void __init console_init_postirq(void)
> +void __init console_init_mem(void)
>  {
>      char *ring;
>      unsigned int i, order, memflags;
> -
> -    serial_init_postirq();
> +    unsigned long flags;
>
>      if ( !opt_conring_size )
> -        opt_conring_size = num_present_cpus() << (9 + xenlog_lower_thresh);
> +        return;
>
>      order = get_order_from_bytes(max(opt_conring_size, conring_size));
>      memflags = MEMF_bits(crashinfo_maxaddr_bits);
> @@ -763,17 +762,28 @@ void __init console_init_postirq(void)
>      }
>      opt_conring_size = PAGE_SIZE << order;
>
> -    spin_lock_irq(&console_lock);
> +    spin_lock_irqsave(&console_lock, flags);

I am not sure why are you change spin_lock_irq() to spin_lock_irqsave() here.
Could you explain this in commit message?

>      for ( i = conringc ; i != conringp; i++ )
>          ring[i & (opt_conring_size - 1)] = conring[i & (conring_size - 1)];
>      conring = ring;
>      smp_wmb(); /* Allow users of console_force_unlock() to see larger 
> buffer. */
>      conring_size = opt_conring_size;
> -    spin_unlock_irq(&console_lock);
> +    spin_unlock_irqrestore(&console_lock, flags);

Ditto.

Daniel

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel