diff options
Diffstat (limited to 'arch/arm/mm/mmu.c')
| -rw-r--r-- | arch/arm/mm/mmu.c | 46 |
1 files changed, 42 insertions, 4 deletions
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 4426ee67ceca..ea67be0223ac 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -21,6 +21,7 @@ #include <asm/cachetype.h> #include <asm/setup.h> #include <asm/sizes.h> +#include <asm/smp_plat.h> #include <asm/tlb.h> #include <asm/highmem.h> @@ -116,6 +117,13 @@ static void __init early_cachepolicy(char **p) } if (i == ARRAY_SIZE(cache_policies)) printk(KERN_ERR "ERROR: unknown or unsupported cache policy\n"); + /* + * This restriction is partly to do with the way we boot; it is + * unpredictable to have memory mapped using two different sets of + * memory attributes (shared, type, and cache attribs). We can not + * change these attributes once the initial assembly has setup the + * page tables. + */ if (cpu_architecture() >= CPU_ARCH_ARMv6) { printk(KERN_WARNING "Only cachepolicy=writeback supported on ARMv6 and later\n"); cachepolicy = CPOLICY_WRITEBACK; @@ -709,10 +717,6 @@ static void __init sanity_check_meminfo(void) if (meminfo.nr_banks >= NR_BANKS) { printk(KERN_CRIT "NR_BANKS too low, " "ignoring high memory\n"); - } else if (cache_is_vipt_aliasing()) { - printk(KERN_CRIT "HIGHMEM is not yet supported " - "with VIPT aliasing cache, " - "ignoring high memory\n"); } else { memmove(bank + 1, bank, (meminfo.nr_banks - i) * sizeof(*bank)); @@ -726,6 +730,8 @@ static void __init sanity_check_meminfo(void) bank->size = VMALLOC_MIN - __va(bank->start); } #else + bank->highmem = highmem; + /* * Check whether this memory bank would entirely overlap * the vmalloc area. @@ -754,6 +760,38 @@ static void __init sanity_check_meminfo(void) #endif j++; } +#ifdef CONFIG_HIGHMEM + if (highmem) { + const char *reason = NULL; + + if (cache_is_vipt_aliasing()) { + /* + * Interactions between kmap and other mappings + * make highmem support with aliasing VIPT caches + * rather difficult. + */ + reason = "with VIPT aliasing cache"; +#ifdef CONFIG_SMP + } else if (tlb_ops_need_broadcast()) { + /* + * kmap_high needs to occasionally flush TLB entries, + * however, if the TLB entries need to be broadcast + * we may deadlock: + * kmap_high(irqs off)->flush_all_zero_pkmaps-> + * flush_tlb_kernel_range->smp_call_function_many + * (must not be called with irqs off) + */ + reason = "without hardware TLB ops broadcasting"; +#endif + } + if (reason) { + printk(KERN_CRIT "HIGHMEM is not supported %s, ignoring high memory\n", + reason); + while (j > 0 && meminfo.bank[j - 1].highmem) + j--; + } + } +#endif meminfo.nr_banks = j; } |