On Thu, 19 Oct 2006 09:41:19 -0700 (PDT) Christoph Lameter <clameter@xxxxxxx> wrote: > On Thu, 19 Oct 2006, KAMEZAWA Hiroyuki wrote: > > > +config ARCH_VMEMMAP_SPARSEMEM_SUPPORT > > + def_bool y > > + depends on PGTABLE_4 && ARCH_SPARSEMEM_ENABLE > > Why do you need to depend on 4 level page tables? > It's based on how big page-table can map. (I'm sorry if my calculation is wrong..) Maximun phyisical address size of Itanium2 looks 50bits. Then, we need sizeof (struct page) * (50 - PAGE_SHIFT) size of virtual address space. #define PTRS_PER_PTD_SHIFT (PAGE_SHIFT-3) #define PTRS_PER_PTE (__IA64_UL(1) << (PTRS_PER_PTD_SHIFT)) #define PMD_SHIFT (PAGE_SHIFT + (PTRS_PER_PTD_SHIFT)) #define PUD_SHIFT (PMD_SHIFT + (PTRS_PER_PTD_SHIFT)) #ifdef CONFIG_PGTABLE_4 #define PGDIR_SHIFT (PUD_SHIFT + (PTRS_PER_PTD_SHIFT)) #else #define PGDIR_SHIFT (PMD_SHIFT + (PTRS_PER_PTD_SHIFT)) #endif Then, considering PAGE_SHIFT=14 case, 4-level-page-table mapsize:(1 << (4 * PAGE_SHIFT - 9) -> (1 << 47) 3-level-page-table mapsize:(1 << (3 * PAGE_SHIFT - 6) -> (1 << 36) we need 4 level. > > +#if defined(CONFIG_VIRTUAL_MEM_MAP) || defined(CONFIG_VMEMMAP_SPARSEMEM) > > unsigned long vmalloc_end = VMALLOC_END_INIT; > > I'd rather stop tinkering around with vmalloc_end. See my patches that I > posted last week to realize virtual memmap. Okay, I'll look into. -Kame - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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