Messages in this thread | | | From | Mike Frysinger <> | Date | Wed, 24 Jun 2009 11:02:48 -0400 | Subject | Re: PREEMPT_ACTIVE too low error with all asm-generic headers for some arches |
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On Wed, Jun 24, 2009 at 10:02, Arnd Bergmann wrote: > On Wednesday 24 June 2009, Ingo Molnar wrote: >> * Mike Frysinger <vapier.adi@gmail.com> wrote: >> > if we look at linux/hardirq.h, it makes this claim: >> > * - bit 28 is the PREEMPT_ACTIVE flag >> > if that's true, then why are we letting any arch set this define ? a >> > quick survey shows that half the arches (11) are using 0x10000000 (bit >> > 28) while the other half (10) are using 0x4000000 (bit 26). and then >> > there is the ia64 oddity which uses bit 30. the exact value here >> > shouldnt really matter across arches though should it ? > > actually alpha, arm and avr32 also use bit 30 (0x40000000), there are only > five (or eight, depending on how you count) architectures (blackfin, h8300, > m68k, s390 and sparc) using bit 26.
meh, too many zeros ;)
>> Correct - what matters is to have no collision between the fields. >> >> > how about adding this to linux/thread_info.h: >> > #ifndef PREEMPT_ACTIVE >> > # ifndef PREEMPT_ACTIVE_BIT >> > # define PREEMPT_ACTIVE_BIT 28 >> > # endif >> > # define PREEMPT_ACTIVE (1 << PREEMPT_ACTIVE_BIT) >> > #endif >> >> Makes sense i guess - but do we really need that level of >> #ifdef nesting? PREEMPT_ACTIVE_BIT should be the main control - with >> a default to 28 if it's not set. PREEMPT_ACTIVE is then derived off >> that, without any #ifdefs. > > I think it would fit better into linux/hardirq.h instead of > linux/thread_info.h, because that is where the other bits of > the preempt count are defined.
agreed
> --- a/include/linux/hardirq.h > +++ b/include/linux/hardirq.h > @@ -62,6 +62,12 @@ > #define HARDIRQ_OFFSET (1UL << HARDIRQ_SHIFT) > #define NMI_OFFSET (1UL << NMI_SHIFT) > > +#ifndef PREEMPT_ACTIVE > +#define PREEMPT_ACTIVE_BITS 1 > +#define PREEMPT_ACTIVE_SHIFT (NMI_SHIFT + NMI_BITS) > +#define PREEMPT_ACTIVE (__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_SHIFT)
i think you meant "<< PREEMPT_ACTIVE_SHIFT" there. once i make that change, it builds fine. -mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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