On Tue, Sep 17, 2013 at 8:53 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> --- linux-2.6.orig/arch/m68k/include/asm/hardirq.h
> +++ linux-2.6/arch/m68k/include/asm/hardirq.h
> @@ -5,17 +5,6 @@
> #include <linux/cache.h>
> #include <asm/irq.h>
>
> -#define HARDIRQ_BITS 8
> --- linux-2.6.orig/include/linux/preempt_mask.h
> +++ linux-2.6/include/linux/preempt_mask.h
> @@ -11,36 +11,22 @@
> * - bits 0-7 are the preemption count (max preemption depth: 256)
> * - bits 8-15 are the softirq count (max # of softirqs: 256)
> *
> - * The hardirq count can in theory reach the same as NR_IRQS.
> - * In reality, the number of nested IRQS is limited to the stack
> - * size as well. For archs with over 1000 IRQS it is not practical
> - * to expect that they will all nest. We give a max of 10 bits for
> - * hardirq nesting. An arch may choose to give less than 10 bits.
> - * m68k expects it to be 8.
m68k needs some changes in arch/m68k/kernel/entry.S, cfr. this check
in arch/m68k/kernel/ints.c:
/* assembly irq entry code relies on this... */
if (HARDIRQ_MASK != 0x00ff0000) {
extern void hardirq_mask_is_broken(void);
hardirq_mask_is_broken();
}
Haven't looked into the details yet...
> - * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
> - * - bit 26 is the NMI_MASK
> - * - bit 27 is the PREEMPT_ACTIVE flag
> + * The hardirq count could in theory be the same as the number of
> + * interrupts in the system, but we run all interrupt handlers with
> + * interrupts disabled, so we cannot have nesting interrupts. Though
> + * there are a few palaeontologic drivers which reenable interrupts in
> + * the handler, so we need more than one bit here.
> *
> * PREEMPT_MASK: 0x000000ff
> * SOFTIRQ_MASK: 0x0000ff00
> - * HARDIRQ_MASK: 0x03ff0000
> - * NMI_MASK: 0x04000000
> + * HARDIRQ_MASK: 0x000f0000
> + * NMI_MASK: 0x00100000
> */
> #define PREEMPT_BITS 8
> #define SOFTIRQ_BITS 8
> +#define HARDIRQ_BITS 4
> #define NMI_BITS 1
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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