内存管理@初始化
来自个人维基
特定于体系结构的设置
x86
start_kernel └ setup_arch └ setup_memory_map └ x86_init.resources.memory_setup └ default_machine_specific_memory_setup //创建一个列表,包括系统占据的内存区和空闲内存区 └ printk(KERN_INFO "BIOS-provided physical RAM map:\n"); └ e820_print_map(who); //打印出结果,如图1 └ paging_init └ pagetable_init └ permanent_kmaps_init └ __flush_tlb_all └ kmap_init
<图1> $dmesg ... BIOS-provided physical RAM map: BIOS-e820: 0000000000000000 -000000000009e800 (usable) BIOS-e820: 000000000009e800 -00000000000a0000 (reserved) BIOS-e820: 00000000000c0000 -00000000000cc000 (reserved) BIOS-e820: 00000000000d8000 -0000000000100000 (reserved) BIOS-e820: 0000000000100000 -0000000017cf0000 (usable) BIOS-e820: 0000000017cf0000 -0000000017cff000 (ACPI data) BIOS-e820: 0000000017cff000 -0000000017d00000 (ACPI NVS) BIOS-e820: 0000000017d00000 -0000000017e80000 (usable) BIOS-e820: 0000000017e80000 -0000000018000000 (reserved) BIOS-e820: 00000000ff800000 -00000000ffc00000 (reserved) BIOS-e820: 00000000fff00000 -0000000100000000 (reserved) ...
#define GFP_ZONE_TABLE ( \ (ZONE_NORMAL << 0 * ZONES_SHIFT) \ | (OPT_ZONE_DMA << ___GFP_DMA * ZONES_SHIFT) \ | (OPT_ZONE_HIGHMEM << ___GFP_HIGHMEM * ZONES_SHIFT) \ | (OPT_ZONE_DMA32 << ___GFP_DMA32 * ZONES_SHIFT) \ | (ZONE_NORMAL << ___GFP_MOVABLE * ZONES_SHIFT) \ | (OPT_ZONE_DMA << (___GFP_MOVABLE | ___GFP_DMA) * ZONES_SHIFT) \ | (ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * ZONES_SHIFT) \ | (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * ZONES_SHIFT) \ ) /* * GFP_ZONE_BAD is a bitmap for all combinations of __GFP_DMA, __GFP_DMA32 * __GFP_HIGHMEM and __GFP_MOVABLE that are not permitted. One flag per * entry starting with bit 0. Bit is set if the combination is not * allowed. */ #define GFP_ZONE_BAD ( \ 1 << (___GFP_DMA | ___GFP_HIGHMEM) \ | 1 << (___GFP_DMA | ___GFP_DMA32) \ | 1 << (___GFP_DMA32 | ___GFP_HIGHMEM) \ | 1 << (___GFP_DMA | ___GFP_DMA32 | ___GFP_HIGHMEM) \ | 1 << (___GFP_MOVABLE | ___GFP_HIGHMEM | ___GFP_DMA) \ | 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_DMA) \ | 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_HIGHMEM) \ | 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_DMA | ___GFP_HIGHMEM) \ ) static inline enum zone_type gfp_zone(gfp_t flags) { enum zone_type z; int bit = (__force int) (flags & GFP_ZONEMASK); z = (GFP_ZONE_TABLE >> (bit * ZONES_SHIFT)) & ((1 << ZONES_SHIFT) - 1); VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); return z; }
gfp_zone函数是作用是,输入 gfp类型,转换成对应的 zone类型输出。
其中,GFP_ZONE_TABLE是
gfp_flags(___GFP_DMA, ___GFP_HIGHMEM, ___GFP_DMA32, ___GFP_MOVABLE)
<==>
zones(ZONE_NORMAL, OPT_ZONE_DMA, OPT_ZONE_HIGHMEM, OPT_ZONE_DMA32, ZONE_MOVABLE)
的对应表;
GFP_ZONE_BAD同样是一个表,以 gfp_flags为位移,对应位的数值为 1表示不允许这样的组合,用来判定 gfp标志组合的合法性。
迁移类型备用列表
/* * This array describes the order lists are fallen back to when * the free lists for the desirable migrate type are depleted */ static int fallbacks[MIGRATE_TYPES][4] = { [MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_RESERVE }, [MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_RESERVE }, #ifdef CONFIG_CMA [MIGRATE_MOVABLE] = { MIGRATE_CMA, MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE }, [MIGRATE_CMA] = { MIGRATE_RESERVE }, /* Never used */ #else [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE }, #endif [MIGRATE_RESERVE] = { MIGRATE_RESERVE }, /* Never used */ #ifdef CONFIG_MEMORY_ISOLATION [MIGRATE_ISOLATE] = { MIGRATE_RESERVE }, /* Never used */ #endif };