From 22adb358e816ce6aa0afb231ae9d826b0bddc8b0 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Sat, 26 May 2007 01:14:43 -0700 Subject: [SPARC64]: Eliminate NR_CPUS limitations. Cheetah systems can have cpuids as large as 1023, although physical systems don't have that many cpus. Only three limitations existed in the kernel preventing arbitrary NR_CPUS values: 1) dcache dirty cpu state stored in page->flags on D-cache aliasing platforms. With some build time calculations and some build-time BUG checks on page->flags layout, this one was easily solved. 2) The cheetah XCALL delivery code could only handle a cpumask with up to 32 cpus set. Some simple looping logic clears that up too. 3) thread_info->cpu was a u8, easily changed to a u16. There are a few spots in the kernel that still put NR_CPUS sized arrays on the kernel stack, but that's not a sparc64 specific problem. Signed-off-by: David S. Miller --- arch/sparc64/mm/init.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) (limited to 'arch/sparc64/mm/init.c') diff --git a/arch/sparc64/mm/init.c b/arch/sparc64/mm/init.c index 977698269d3..087cbf09d0b 100644 --- a/arch/sparc64/mm/init.c +++ b/arch/sparc64/mm/init.c @@ -191,12 +191,9 @@ inline void flush_dcache_page_impl(struct page *page) } #define PG_dcache_dirty PG_arch_1 -#define PG_dcache_cpu_shift 24UL -#define PG_dcache_cpu_mask (256UL - 1UL) - -#if NR_CPUS > 256 -#error D-cache dirty tracking and thread_info->cpu need fixing for > 256 cpus -#endif +#define PG_dcache_cpu_shift 32UL +#define PG_dcache_cpu_mask \ + ((1UL<flags >> PG_dcache_cpu_shift) & PG_dcache_cpu_mask) @@ -1349,6 +1346,19 @@ void __init paging_init(void) unsigned long end_pfn, pages_avail, shift, phys_base; unsigned long real_end, i; + /* These build time checkes make sure that the dcache_dirty_cpu() + * page->flags usage will work. + * + * When a page gets marked as dcache-dirty, we store the + * cpu number starting at bit 32 in the page->flags. Also, + * functions like clear_dcache_dirty_cpu use the cpu mask + * in 13-bit signed-immediate instruction fields. + */ + BUILD_BUG_ON(FLAGS_RESERVED != 32); + BUILD_BUG_ON(SECTIONS_WIDTH + NODES_WIDTH + ZONES_WIDTH + + ilog2(roundup_pow_of_two(NR_CPUS)) > FLAGS_RESERVED); + BUILD_BUG_ON(NR_CPUS > 4096); + kern_base = (prom_boot_mapping_phys_low >> 22UL) << 22UL; kern_size = (unsigned long)&_end - (unsigned long)KERNBASE; -- cgit v1.2.3-70-g09d2