Android系统中添加内存分区（Zone）

1.  添加zone_type枚举类型

//路径: include/linux/Mmzone.henum zone_type {#ifdef CONFIG_ZONE_DMA/* * ZONE_DMA is used when there are devices that are not able * to do DMA to all of addressable memory (ZONE_NORMAL). Then we * carve out the portion of memory that is needed for these devices. * The range is arch specific. * * Some examples * * ArchitectureLimit * --------------------------- * parisc, ia64, sparc<4G * s390<2G * armVarious * alphaUnlimited or 0-16MB. * * i386, x86_64 and multiple other arches * <16M. */ZONE_DMA,#endif#ifdef CONFIG_ZONE_DMA32/* * x86_64 needs two ZONE_DMAs because it supports devices that are * only able to do DMA to the lower 16M but also 32 bit devices that * can only do DMA areas below 4G. */ZONE_DMA32,#endif/* * Normal addressable memory is in ZONE_NORMAL. DMA operations can be * performed on pages in ZONE_NORMAL if the DMA devices support * transfers to all addressable memory. */ZONE_NORMAL,        ZONE_MEMSWAP,#ifdef CONFIG_HIGHMEM/* * A memory area that is only addressable by the kernel through * mapping portions into its own address space. This is for example * used by i386 to allow the kernel to address the memory beyond * 900MB. The kernel will set up special mappings (page * table entries on i386) for each page that the kernel needs to * access. */ZONE_HIGHMEM,#endifZONE_MOVABLE,__MAX_NR_ZONES};

其中

ZONE_MEMSWAP,

即为添加zone对应的枚举类型

2. 修改内存初始化代码

//路径 arch/arm/mm/Init.cstatic void __init arm_bootmem_free(unsigned long min, unsigned long max_low,unsigned long max_high)

添加代码

unsigned long mem_swap_size = 1UL << 15;    unsigned long normal_start = min, normal_end = max_low - mem_swap_size;

zone_size[0] = normal_end - normal_start;zone_size[ZONE_MEMSWAP] = mem_swap_size;

#ifdef CONFIG_HIGHMEMzone_size[ZONE_HIGHMEM] = max_high - max_low;#endif

zhole_size[ZONE_MEMSWAP] = 0UL;for_each_memblock(memory, reg) {unsigned long start = memblock_region_memory_base_pfn(reg);unsigned long end = memblock_region_memory_end_pfn(reg);if (start < normal_end) {unsigned long low_end = min(end, normal_end);zhole_size[0] -= low_end - start;}

#ifdef CONFIG_HIGHMEMif (end > max_low) {unsigned long high_start = max(start, max_low);zhole_size[ZONE_HIGHMEM] -= end - high_start;}#endif

3. 修改内存分配代码

//路径：mm/page_alloc.cget_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,struct zonelist *zonelist, int high_zoneidx, int alloc_flags,struct zone *preferred_zone, int migratetype)

在上面函数的下述for循环开头添加如下代码：

for_each_zone_zonelist_nodemask(zone, z, zonelist,high_zoneidx, nodemask) {...        if (zone_idx(zone) == ZONE_MEMSWAP)            continue;...}

<pre name="code" class="cpp">同样是该路径的该函数：static char * const zone_names[MAX_NR_ZONES] = {#ifdef CONFIG_ZONE_DMA "DMA",#endif#ifdef CONFIG_ZONE_DMA32 "DMA32",#endif "Normal",     "MemSwap",#ifdef CONFIG_HIGHMEM "HighMem",#endif "Movable",};