Re: [PATCH] Fix infinite loop in grub_pit_wait()

[Marco Gerards <mgerards@xs4all.nl>]

Christian Franke <Christian.Franke@t-online.de> writes:

> grub2 from current SVN hangs if run in VirtualPC, the problem was
> introduced with 'svn diff -r 1779:1780'.
>
> Here is a proposed fix.
>
> Christian
>
> 2008-08-07  Christian Franke  <franke@computer.org>
>
> 	* kern/i386/pit.c (TIMER2_SPEAKER): New define.
> 	(TIMER2_GATE): Likewise.
> 	(grub_pit_wait): Add enable/disable of the timer2 gate
> 	bit of port 0x61. This fixes a possible infinite loop.

Small nitpick: use a double space

> diff --git a/kern/i386/pit.c b/kern/i386/pit.c
> index d0a6eda..a3fab26 100644
> --- a/kern/i386/pit.c
> +++ b/kern/i386/pit.c
> @@ -28,13 +28,26 @@
>  #define TIMER_ENABLE_LSB	0x20
>  #define TIMER_ENABLE_MSB	0x10
>  #define TIMER2_LATCH		0x20
> +#define TIMER2_SPEAKER		0x02
> +#define TIMER2_GATE		0x01
>  
>  void
>  grub_pit_wait (grub_uint16_t tics)
>  {
> +  /* Disable timer2 gate and speaker.  */
> +  grub_outb (grub_inb (TIMER2_REG_LATCH) & ~ (TIMER2_SPEAKER | TIMER2_GATE), TIMER2_REG_LATCH);
> +
> +  /* Set tics.  */
>    grub_outb (TIMER2_SELECT | TIMER_ENABLE_LSB | TIMER_ENABLE_MSB, TIMER_REG_COMMAND);
>    grub_outb (tics & 0xff, TIMER2_REG_CONTROL);
>    grub_outb (tics >> 8, TIMER2_REG_CONTROL);
>  
> +  /* Enable timer2 gate, keep speaker disabled.  */
> +  grub_outb ((grub_inb (TIMER2_REG_LATCH) & ~ TIMER2_SPEAKER) | TIMER2_GATE, TIMER2_REG_LATCH);
> +
> +  /* Wait.  */
>    while ((grub_inb (TIMER2_REG_LATCH) & TIMER2_LATCH) == 0x00);
> +
> +  /* Disable timer2 gate and speaker.  */
> +  grub_outb (grub_inb (TIMER2_REG_LATCH) & ~ (TIMER2_SPEAKER | TIMER2_GATE), TIMER2_REG_LATCH);
These lines are too long, please break them properly.



--
Marco