Messages in this thread | | | Date | 29 Jul 2005 11:18:04 -0400 | From | linux@horizon ... | Subject | Re: Add prefetch switch stack hook in scheduler function |
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> include/asm-alpha/mmu_context.h | 6 ++++++ > include/asm-arm/mmu_context.h | 6 ++++++ > include/asm-arm26/mmu_context.h | 6 ++++++ > include/asm-cris/mmu_context.h | 6 ++++++ > include/asm-frv/mmu_context.h | 6 ++++++ > include/asm-h8300/mmu_context.h | 6 ++++++ > include/asm-i386/mmu_context.h | 6 ++++++ > include/asm-ia64/mmu_context.h | 6 ++++++ > include/asm-m32r/mmu_context.h | 6 ++++++ > include/asm-m68k/mmu_context.h | 6 ++++++ > include/asm-m68knommu/mmu_context.h | 6 ++++++ > include/asm-mips/mmu_context.h | 6 ++++++ > include/asm-parisc/mmu_context.h | 6 ++++++ > include/asm-ppc/mmu_context.h | 6 ++++++ > include/asm-ppc64/mmu_context.h | 6 ++++++ > include/asm-s390/mmu_context.h | 6 ++++++ > include/asm-sh/mmu_context.h | 6 ++++++ > include/asm-sh64/mmu_context.h | 6 ++++++ > include/asm-sparc/mmu_context.h | 6 ++++++ > include/asm-sparc64/mmu_context.h | 6 ++++++ > include/asm-um/mmu_context.h | 6 ++++++ > include/asm-v850/mmu_context.h | 6 ++++++ > include/asm-x86_64/mmu_context.h | 5 +++++ > include/asm-xtensa/mmu_context.h | 6 ++++++ > kernel/sched.c | 9 ++++++++- > 25 files changed, 151 insertions(+), 1 deletion(-)
I think this pretty clearly points out the need for some arch-generic infrastructure in Linux. An awful lot of arch hooks are for one or two architectures with some peculiarities, and the other 90% of the implementations are identical.
For example, this is 22 repetitions of #define MIN_KERNEL_STACK_FOOTPRINT L1_CACHE_BYTES
with one different case.
It would be awfully nice if there was a standard way to provide a default implementation that was automatically picked up by any architecture that didn't explicitly override it.
One possibility is to use #ifndef:
/* asm-$PLATFORM/foo.h */ #define MIN_KERNEL_STACK_FOOTPRINT IA64_SWITCH_STACK_SIZE inline void prefetch_task(struct task_struct const *task) { ... } #define prefetch_task prefetch_task
/* asm-generic/foo.h */ #include <asm/foo.h>
#ifndef MIN_KERNEL_STACK_FOOTPRINT #define MIN_KERNEL_STACK_FOOTPRINT L1_CACHE_BYTES #endif
#ifndef prefetch_task inline void prefetch_task(struct task_struct const *task) { } /* The #define is OPTIONAL... */ #define prefetch_task prefetch_task #endif
But both understanding and maintaining the arch code could be much easier if the shared parts were collapsed. A comment in the generic versions can explain what the assumptions are.
If there are cases where there is more than one implementation with multiple users, it can be stuffed into a third category of headers. E.g. <asm-generic/noiommu/foo.h> and <asm-generic/iommu/foo.h> or some such, using the same duplicate-suppression technique and #included at the end of <asm-$PLATFORM/foo.h> - 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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