mips架构linux启动分析(六)(arch_mem_init(node内存)内存初始化)

这里开始就是各个node的内存的初始化了。
OK，直接看代码.

static void __init arch_mem_init(char **cmdline_p){extern void plat_mem_setup(void);//定义板级的屏幕的相关信息plat_mem_setup();//把代码段也加入到boot_mem_map进行管理(bootm机制)arch_mem_addpart(PFN_DOWN(__pa_symbol(&_text)) << PAGE_SHIFT, PFN_UP(__pa_symbol(&_edata)) << PAGE_SHIFT, BOOT_MEM_RAM);//把init段(初始化段)也加入到boot_mem_map中进行管理arch_mem_addpart(PFN_UP(__pa_symbol(&__init_begin)) << PAGE_SHIFT, PFN_DOWN(__pa_symbol(&__init_end)) << PAGE_SHIFT, BOOT_MEM_INIT_RAM);//在arcs_cmdline之后加入一个空格后,在把builtin_cmdline加入其中if (builtin_cmdline[0]) {   strlcat(arcs_cmdline, " ", COMMAND_LINE_SIZE);   strlcat(arcs_cmdline, builtin_cmdline, COMMAND_LINE_SIZE);}//把arcs_cmdline拷贝到boot_command_linestrlcpy(boot_command_line, arcs_cmdline, COMMAND_LINE_SIZE);//把boot_command_line拷贝到command_line中strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);//用指针cmdline_p指向command_line*cmdline_p = command_line;//对参数进行解析parse_early_param();//bootmem的初始化bootmem_init();//mips中crashkernel时的信息段mips_parse_crashkernel();//把crashkernel段设置为保留段if (crashk_res.start != crashk_res.end)reserve_bootmem(crashk_res.start,crashk_res.end - crashk_res.start + 1,BOOTMEM_DEFAULT);//空函数device_tree_init();//分配的一个非线形段(no_liner section),具体作用,还不是很清楚??????????sparse_init();//tlb信息的初始化plat_swiotlb_setup();设置区zonespaging_init();}

定义板级screen的信息:

void __init plat_mem_setup(void){#ifdef CONFIG_VT#if defined(CONFIG_VGA_CONSOLE)conswitchp = &vga_con;screen_info = (struct screen_info) {.orig_x= 0,.orig_y= 25,.orig_video_cols= 80,.orig_video_lines= 25,.orig_video_isVGA= VIDEO_TYPE_VGAC,.orig_video_points= 16,};#elif defined(CONFIG_DUMMY_CONSOLE)conswitchp = &dummy_con;#endif#endif}

怎么把一个段加入到boot_mem_map中进行管理呢?

static void __init arch_mem_addpart(phys_t mem, phys_t end, int type){phys_t size;int i;size = end - mem;//如果要加入的段在boot_mem_map中，就退出for (i = 0; i < boot_mem_map.nr_map; i++) {if (mem >= boot_mem_map.map[i].addr &&    mem < (boot_mem_map.map[i].addr +   boot_mem_map.map[i].size))return;}//把这段区域加入到boot_mem_map中add_memory_region(mem, size, type);}

void __init add_memory_region(phys_t start, phys_t size, long type){int x = boot_mem_map.nr_map;int i;//把要加入的段和已有的段进行合并for (i = 0; i < boot_mem_map.nr_map; i++) {//从boot_mem_map第一个开始读取struct boot_mem_map_entry *entry = boot_mem_map.map + i;unsigned long top;//如果类型不同,则进行下一个if (entry->type != type)continue;//如果这个region大于要加入段的地址，则进行下一个if (start + size < entry->addr)continue;/* no overlap *///如果这个region小于要加入段的地址，则进行下一个if (entry->addr + entry->size < start)continue;/* no overlap *///到这里说明两个地址有重叠的部分,然后进行合并top = max(entry->addr + entry->size, start + size);entry->addr = min(entry->addr, start);entry->size = top - entry->addr;return;}//如果没有重叠的region，则增加一个新的boot_mem_map进行管理boot_mem_map.map[x].addr = start;boot_mem_map.map[x].size = size;boot_mem_map.map[x].type = type;boot_mem_map.nr_map++;}

bootmem的初始化：

static void __init bootmem_init(void){//initrd的初始化    init_initrd();    finalize_initrd();}

static unsigned long __init init_initrd(void){unsigned long end;/* *判断现在的initrd时有效的 */if (!initrd_start || initrd_end <= initrd_start)goto disable;//判断initrd是不是页对齐的if (initrd_start & ~PAGE_MASK) {pr_err("initrd start must be page aligned\n");goto disable;}if (initrd_start < PAGE_OFFSET) {pr_err("initrd start < PAGE_OFFSET\n");goto disable;}//end保存initrd_end的物理地址end = __pa(initrd_end);//initrd_end保存initrd_end的虚拟地址initrd_end = (unsigned long)__va(end);//initrd_start保存initrd_start的虚拟地址initrd_start = (unsigned long)__va(__pa(initrd_start));ROOT_DEV = Root_RAM0;//返回initrd_end的物理页帧地址return PFN_UP(end);disable:initrd_start = 0;initrd_end = 0;return 0;}

static void __init finalize_initrd(void){unsigned long size = initrd_end - initrd_start;//判断initrd段长是否为零if (size == 0) {printk(KERN_INFO "Initrd not found or empty");goto disable;}//如果initrd_end的物理地址大于lax_low_pfn则initrd越界if (__pa(initrd_end) > PFN_PHYS(max_low_pfn)) {printk(KERN_ERR "Initrd extends beyond end of memory");goto disable;}//把initrd内存设置为reservereserve_bootmem(__pa(initrd_start), size, BOOTMEM_DEFAULT);initrd_below_start_ok = 1;pr_info("Initial ramdisk at: 0x%lx (%lu bytes)\n",initrd_start, size);return;disable:printk(KERN_CONT " - disabling initrd\n");initrd_start = 0;initrd_end = 0;}

把内存设置为reserve内存的方法

#define PFN_UP(x)(((x)+PAGE_SIZE-1)>>PAGE_SHIFT) //低位有数则页帧号加1#define PFN_DOWN(x)((x)>>PAGE_SHIFT)//舍弃低位

int __init reserve_bootmem(unsigned long addr, unsigned long size,    int flags){unsigned long start, end;//设置开始结束地址格式start = PFN_DOWN(addr);end = PFN_UP(addr + size);//把start-end间的内存设置为reservereturn mark_bootmem(start, end, 1, flags);}

static int __init mark_bootmem(unsigned long start, unsigned long end,int reserve, int flags){unsigned long pos;bootmem_data_t *bdata;pos = start;//遍历bdata_list链表,找到要标记的内存的区间list_for_each_entry(bdata, &bdata_list, list) {int err;unsigned long max;if (pos < bdata->node_min_pfn ||    pos >= bdata->node_low_pfn) {BUG_ON(pos != start);continue;}max = min(bdata->node_low_pfn, end);//调用a会念书mark_bootmem_node把区间设置为已分配err = mark_bootmem_node(bdata, pos, max, reserve, flags);if (reserve && err) {mark_bootmem(start, pos, 0, 0);return err;}if (max == end)return 0;pos = bdata->node_low_pfn;}BUG();}

static int __init mark_bootmem_node(bootmem_data_t *bdata,unsigned long start, unsigned long end,int reserve, int flags){unsigned long sidx, eidx;bdebug("nid=%td start=%lx end=%lx reserve=%d flags=%x\n",bdata - bootmem_node_data, start, end, reserve, flags);//安全检查,确定要标记的内存的区间是存在的BUG_ON(start < bdata->node_min_pfn);BUG_ON(end > bdata->node_low_pfn);//获取偏移大小sidx = start - bdata->node_min_pfn;eidx = end - bdata->node_min_pfn;//调用__reserve设置为已分配,__free释放if (reserve)return __reserve(bdata, sidx, eidx, flags);else__free(bdata, sidx, eidx);return 0;}

static void __init __free(bootmem_data_t *bdata,unsigned long sidx, unsigned long eidx){unsigned long idx;//记录这里分配的值if (bdata->hint_idx > sidx)bdata->hint_idx = sidx;//调用test_and_clear_bit把对应的位清零for (idx = sidx; idx < eidx; idx++)if (!test_and_clear_bit(idx, bdata->node_bootmem_map))BUG();}static int __init __reserve(bootmem_data_t *bdata, unsigned long sidx,unsigned long eidx, int flags){unsigned long idx;int exclusive = flags & BOOTMEM_EXCLUSIVE;//调用test_and_set_bit把位图对应的位设置位1,原子操作for (idx = sidx; idx < eidx; idx++)if (test_and_set_bit(idx, bdata->node_bootmem_map)) {if (exclusive) {__free(bdata, sidx, idx);return -EBUSY;}}return 0;}

具体的各个node初始化函数:

void __init paging_init(void){unsigned node;unsigned long zones_size[MAX_NR_ZONES] = {0, };//初始化tlb表项pagetable_init();//获取每个node的内存区间for_each_online_node(node) {unsigned long  start_pfn, end_pfn;get_pfn_range_for_nid(node, &start_pfn, &end_pfn);if (end_pfn > max_low_pfn)max_low_pfn = end_pfn;}#ifdef CONFIG_ZONE_DMA32//设置ZONE_DMA32区间大小zones_size[ZONE_DMA32] = MAX_DMA32_PFN;#endif//设置NORMAL区间大小zones_size[ZONE_NORMAL] = max_low_pfn;//对这个node的zone进行初始化free_area_init_nodes(zones_size);}

void __init free_area_init_nodes(unsigned long *max_zone_pfn){unsigned long start_pfn, end_pfn;int i, nid;/*arch_zone_lowest_possible_pfn记录每个node的起始地址*arch_zone_highest_possible_pfn记录每个node的结束地址*在这里进行清零操作*/memset(arch_zone_lowest_possible_pfn, 0,sizeof(arch_zone_lowest_possible_pfn));memset(arch_zone_highest_possible_pfn, 0,sizeof(arch_zone_highest_possible_pfn));//根据memblock找到目前系统中的最低内存地址      arch_zone_lowest_possible_pfn[0] = find_min_pfn_with_active_regions();//根据参数传递进来的值,得到最大的物理内存    arch_zone_highest_possible_pfn[0] = max_zone_pfn[0];for (i = 1; i < MAX_NR_ZONES; i++) {if (i == ZONE_MOVABLE)continue;//循环操作,第1个块的低地址,是第0块的高地址arch_zone_lowest_possible_pfn[i] =arch_zone_highest_possible_pfn[i-1];arch_zone_highest_possible_pfn[i] =max(max_zone_pfn[i], arch_zone_lowest_possible_pfn[i]);}arch_zone_lowest_possible_pfn[ZONE_MOVABLE] = 0;arch_zone_highest_possible_pfn[ZONE_MOVABLE] = 0;/* Find the PFNs that ZONE_MOVABLE begins at in each node */memset(zone_movable_pfn, 0, sizeof(zone_movable_pfn));find_zone_movable_pfns_for_nodes();//对每个node都调用free_area_init_node进行初始化/* Initialise every node */mminit_verify_pageflags_layout();setup_nr_node_ids();for_each_online_node(nid) {pg_data_t *pgdat = NODE_DATA(nid);free_area_init_node(nid, NULL,find_min_pfn_for_node(nid), NULL);/* Any memory on that node */if (pgdat->node_present_pages)node_set_state(nid, N_MEMORY);check_for_memory(pgdat, nid);}}

看一下是怎么初始化每个node的内存区域的：

void __init_refok free_area_init_node(int nid, unsigned long *zones_size,unsigned long node_start_pfn, unsigned long *zholes_size){pg_data_t *pgdat = NODE_DATA(nid);unsigned long start_pfn = 0;unsigned long end_pfn = 0;//初始化first_deferred_pfn成员reset_deferred_meminit(pgdat);//设置node的号pgdat->node_id = nid;//设置开始地址pgdat->node_start_pfn = node_start_pfn;//获取这个node对应的内存的开始结束地址get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);//计算这个node的所有page(spanned_page),以及可用page(present_page)calculate_node_totalpages(pgdat, start_pfn, end_pfn,  zones_size, zholes_size);//如果不支持FLAT_MEM_NODE_MAP这个函数就为空alloc_node_mem_map(pgdat);//核心初始化函数,初始化node_data结构体free_area_init_core(pgdat, start_pfn, end_pfn);}

zone的结构体:

zone的结构体:struct zone {unsigned long watermark[NR_WMARK];  //水位设置,内存回收时使用unsigned long percpu_drift_mark;unsigned longlowmem_reserve[MAX_NR_ZONES];unsigned longdirty_balance_reserve;#ifdef CONFIG_NUMAint node;              //node号unsigned longmin_unmapped_pages;unsigned longmin_slab_pages;#endifstruct per_cpu_pageset __percpu *pageset;spinlock_tlock;int                     all_unreclaimable; /* All pages pinned */#if defined CONFIG_COMPACTION || defined CONFIG_CMAboolcompact_blockskip_flush;unsigned longcompact_cached_free_pfn;unsigned longcompact_cached_migrate_pfn;#endif#ifdef CONFIG_MEMORY_HOTPLUGseqlock_tspan_seqlock;#endifstruct free_areafree_area[MAX_ORDER];#ifndef CONFIG_SPARSEMEMunsigned long*pageblock_flags;#endif /* CONFIG_SPARSEMEM */#ifdef CONFIG_COMPACTIONunsigned intcompact_considered;unsigned intcompact_defer_shift;intcompact_order_failed;#endifZONE_PADDING(_pad1_)spinlock_tlru_lock;struct lruveclruvec;atomic_long_tinactive_age;unsigned longpages_scanned;   /* since last reclaim */unsigned longflags;   /*zone flags*/atomic_long_tvm_stat[NR_VM_ZONE_STAT_ITEMS];unsigned int inactive_ratio;ZONE_PADDING(_pad2_)//等待队列wait_queue_head_t* wait_table;unsigned longwait_table_hash_nr_entries; //等待数量unsigned longwait_table_bits;struct pglist_data*zone_pgdat;    //指向所属的pgdatunsigned longzone_start_pfn; //zone的开始地址unsigned longspanned_pages; //总的大小,包括holeunsigned longpresent_pages; //不包括hole的大小unsigned longmanaged_pages; intnr_migrate_reserve_block;const char*name;   //名字} ____cacheline_internodealigned_in_smp;

zone结构的初始化(这里很多初始化对齐作用不是很了解,只要先知道这里时初始化zone就好了；等了解了内存回收机制时, 对这里的作用就清楚了)

//zone结构体初始化,其中涉及到很多内存回收时使用的成员,static void __paginginit free_area_init_core(struct pglist_data *pgdat,unsigned long node_start_pfn, unsigned long node_end_pfn){enum zone_type j;int nid = pgdat->node_id;int ret;/初始化node_data中的成员pgdat_resize_init(pgdat);#ifdef CONFIG_NUMA_BALANCINGspin_lock_init(&pgdat->numabalancing_migrate_lock);pgdat->numabalancing_migrate_nr_pages = 0;pgdat->numabalancing_migrate_next_window = jiffies;#endifinit_waitqueue_head(&pgdat->kswapd_wait);init_waitqueue_head(&pgdat->pfmemalloc_wait);pgdat_page_cgroup_init(pgdat);//for循环,更新这个node中所有的zone的信息for (j = 0; j < REAL_MAX_ZONES; j++) {struct zone *zone = pgdat->node_zones + j;unsigned long size, realsize, freesize, memmap_pages;unsigned long zone_start_pfn;zone_start_pfn = zone->zone_start_pfn;size = zone->spanned_pages;realsize = freesize = zone->present_pages;memmap_pages = calc_memmap_size(size, realsize);if (freesize >= memmap_pages) {freesize -= memmap_pages;if (memmap_pages)printk(KERN_DEBUG  "%s zone: %lu pages used for memmap\n",       zone_names[j], memmap_pages);} elseprintk(KERN_WARNING   "%s zone: %lu pages exceeds freesize %lu\n",zone_names[j], memmap_pages, freesize);/* Account for reserved pages */if (j == 0 && freesize > dma_reserve) {freesize -= dma_reserve;printk(KERN_DEBUG "  %s zone: %lu pages reserved\n",zone_names[0], dma_reserve);}if (!is_highmem_idx(j))nr_kernel_pages += freesize;else if (nr_kernel_pages > memmap_pages * 2)nr_kernel_pages -= memmap_pages;nr_all_pages += freesize;zone->managed_pages = is_highmem_idx(j) ? realsize : freesize;#ifdef CONFIG_NUMAzone->node = nid;zone->min_unmapped_pages=(freesize*sysctl_min_unmapped_ratio)/100;zone->min_slab_pages = (freesize * sysctl_min_slab_ratio) / 100;#endif//更新zone的namezone->name = zone_names[j];//锁初始化spin_lock_init(&zone->lock);spin_lock_init(&zone->lru_lock);zone_seqlock_init(zone);//指向zone所属的pgdatzone->zone_pgdat = pgdat;zone_pcp_init(zone);/* For bootup, initialized properly in watermark setup */mod_zone_page_state(zone, NR_ALLOC_BATCH, zone->managed_pages);lruvec_init(&zone->lruvec);if (!size)continue;set_pageblock_order();setup_usemap(pgdat, zone, zone_start_pfn, size);ret = init_currently_empty_zone(zone, zone_start_pfn,size, MEMMAP_EARLY);BUG_ON(ret);memmap_init(size, nid, j, zone_start_pfn);}}

好了，现在node中的zone就填写完毕了。

OK，运行到这里,每个node对应的内存区域就已经初始化完毕了。

下面还由几个板级相关的点,记录下,比较重要,需要进行分析:

1,page_init中的pagetable_init函数,这是初始化pgd,pud,pmd,pte的表项,也就是虚拟地址到物理地址的转换
2,arch_mem_init函数中的aparse_init,功能数初始化一段非线形区域,具体作用还不是很清楚?????????????????????????????????????????
3,arch_mem_init函数中的plat_swiotlb_setup函数, 这是关于DMA操作,涉及到具体板卡的地址映射问题.
4,setup_arch函数中的plat_smp_setup,是mips多核cpu之间的IPI初始化,也就是核间互连寄存器的初始化(手册说的比较少,单看代码也不了解具体功能)
5,setup_arch函数中的cpu_cache_init函数，这是cpu的cache初始化。