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setup_arch

已有 996 次阅读| 2010-7-20 23:19 |个人分类:Linux移植

分析setup_arch(setup.c)：

setup_processor 设置处理器的类型，并进行初始化

setup_machine 返回机器类型描述结构体信息
setup_arch()对内核参数的解析
setup_arch()函数是体系结构相关的内核初始化过程，这其中对内核参数有涉及的变量和操作如下
void __init setup_arch(char **cmdline_p)
{
char *from = default_command_line;
//定义了一个指向default_command_line的指针
…
//这里可能存在一些对from操作的machine-dep的函数
…
memcpy(saved_command_line, from, COMMAND_LINE_SIZE);
//这时的from所指向的就是完整待解析的内核参数，将它复
//制到saved_command_line中去（以供start_kernel()打印）
//之所以不直接使用default_command_line是因为在此之前
//有可能定义一些具体板子相关的对from的操作
saved_command_line[COMMAND_LINE_SIZE-1] = '\0';
//最后一位置为NULL
parse_cmdline(&meminfo, cmdline_p, from);
//调用parse_cmdline处理from指向的内核参数中关于内存的//部分
}
parse_cmdline 用于解析内核参数中关于内存的部分
parse_cmdline对内核参数的解析
parse_cmdline做了三件事，首先它解析了from所指向的完整的内核参数，中关于内存的部分，其次它将没有解析的部分复制到command_line中，最后它将start_kernel()传进来的内核参数指针指向command_line
内核参数中的“mem=xxxM@xxx”将会被parse_cmdline解析，并根据结果设置meminfo，而其余部分则被复制到command_line中

判断是软reboot还是硬reboot
指明代码段和数据段的起始地址和结束地址
bootmem_init()为了在启动阶段描述内存使用情况我们需要一些内存空间，这些空间叫做bootmem
void __init bootmem_init(struct meminfo *mi)
{
struct node_info node_info[NR_NODES], *np = node_info;
unsigned int bootmap_pages, bootmap_pfn, map_pg;
int node, initrd_node;
bootmap_pages = find_memend_and_nodes(mi, np);后面会详细分析这个函数，为了在
启动阶段描述内存使用情况我们需要一些内存空间，这些空间叫做bootmem，此时bootm
ap_pages表明了bootmem所需要的pages的数目
bootmap_pfn   = find_bootmap_pfn(0, mi, bootmap_pages); 后面会详细分析这个函
数，通过这个函数，bootmap_pfn设置了bootmem所在的初始页号。也就是说从bootmap_
pfn到bootmap_pfn + bootmap_pages的内存页被用来描述初始化的时候的内存的用用情
况
initrd_node   = check_initrd(mi);//俺们的板子没有用，应该是检查ramdisk的节点情况
map_pg = bootmap_pfn;
np += numnodes - 1;
初始化node结构
for (node = numnodes - 1; node >= 0; node--, np--) {
if (np->end == 0) {
   if (node == 0)
    BUG();
   continue;
}
init_bootmem_node(NODE_DATA(node), map_pg, np->start, np->end); 后面会详细
分析这个函数
free_bootmem_node_bank(node, mi);//释放所有内存，也就是把bootmem的区域全部
设置为0
map_pg += np->bootmap_pages;
我们有可能会保留一些内存以便使值不能被动态分配，具体要保留什么内容，后面会详
细分析
if (node == 0)
   reserve_node_zero(bootmap_pfn, bootmap_pages);
}
if (map_pg != bootmap_pfn + bootmap_pages)
BUG();
}

paging_init 页表初始化
创建内核页表，映射所有物理内存和io空间，对于不同的处理器，这个函数差别很大。这个函数里面东西比较多，改天抽个时间认真研究一下！

request_standard_resources 建立资源链表
内核映象所占用的物理页面不允许动态分配，内核代码段和数据段所占用空间不能分配。

parse_options 解析命令行参数中剩下的部分（跟parse_cmdline 相比较）主要是环境变量和要执行的第一个脚本linuxrc

trap_init 主要是对一些系统保留的中断向量的初始化，下面是entry-armv.S中向量表的初始化
.LCvectors: swi SYS_ERROR0
  b __real_stubs_start + (vector_undefinstr - __stubs_start)
  ldr pc, __real_stubs_start + (.LCvswi - __stubs_start)
  b __real_stubs_start + (vector_prefetch - __stubs_start)
  b __real_stubs_start + (vector_data - __stubs_start)
  b __real_stubs_start + (vector_addrexcptn - __stubs_start)
  b __real_stubs_start + (vector_IRQ - __stubs_start)
  b __real_stubs_start + (vector_FIQ - __stubs_start)

init_IRQ 做与中断处理相关的初始化，将所有中断注册一个中断描述符。其中还要做dma的初始化。

浅析armlinux-setup_arch()->setup_arch()函数-最终

浅析armlinux-setup_arch()->setup_arch()函数-最终文章来源:http://gliethttp.cublog.cn 建议首先参考《浅析armlinux2_4_19启动程序[head-armv.s文件]》与[http://gliethttp.cublog.cn] 《浅析setup_arch()函数tag_list的uboot[u-boot]由来》《浅析armlinux-setup_arch()->setup_processor()函数1》《浅析armlinux-setup_arch()->setup_machine()函数2 》《浅析armlinux-setup_arch()->convert_to_tag_list()函数3 》《浅析armlinux-setup_arch()->bootmem_init()函数4》《浅析armlinux-setup_arch()->paging_init()函数5》《浅析armlinux-seup_arch-alloc_bootmem_low_pages函数5-1》《浅析armlinux-setup_arch()-memtable_init()函数5-2》《浅析armlinux-setup_arch()-clear_mapping()函数5-2-1》《浅析armlinux-setup_arch()-create_mapping()函数5-2-2》《我看Buddy(伙伴)算法－为什么要有除2操作》《浅析armlinux-paging_init()->at91rm9200_map_io()函数5-3》《浅析armlinux-paging_init()->free_area_init_core()函数5-4》《浅析armlinux-setup_arch()->request_standard_resources()函数6》《浅析armlinux-setup_arch()->init_arch_irq()函数7》 //1.arch/arm/kernel/Setup.c->setup_arch() void __init setup_arch(char **cmdline_p) { struct tag *tags = (struct tag *)&init_tags; struct machine_desc *mdesc; char *from = default_command_line; ROOT_DEV = MKDEV(0, 255);//ROOT_DEV = 0xff; //见《浅析armlinux-setup_arch()->setup_processor()函数1》[http://gliethttp.cublog.cn] setup_processor(); //见《浅析armlinux-setup_arch()->setup_machine(machine_arch_type)函数2》[http://gliethttp.cublog.cn] mdesc = setup_machine(machine_arch_type);//mdesc指向机器描述空间单元 //++++++++++++++ //arch/arm/mach-at91rm9200/Core.c //位于.arch.info段 //MACHINE_START(AT91RM9200, "ATMEL AT91RM9200")//.nr = MACH_TYPE_##_type=MACH_TYPE_AT91RM9200=251 //与上面从u-boot传到r1中的一样[gliethttp] //MAINTAINER("SAN People / ATMEL") //BOOT_MEM(AT91_SDRAM_BASE, AT91C_BASE_SYS, AT91C_VA_BASE_SYS) //BOOT_PARAMS(AT91_SDRAM_BASE + 0x100)//tag list存放的物理地址0x20000100[gliethttp] //FIXUP(at91rm9200_fixup) //MAPIO(at91rm9200_map_io) //INITIRQ(at91rm9200_init_irq) //MACHINE_END[gliethttp] //-------------- machine_name = mdesc->name;//machine_name="ATMEL AT91RM9200" if (mdesc->soft_reboot)//mdesc->soft_reboot初值为1 reboot_setup("s");//分析见后 if (mdesc->param_offset)//mdesc->param_offset=AT91_SDRAM_BASE + 0x100=物理地址0x20000100 tags = phys_to_virt(mdesc->param_offset);//将tag list物理地址转换成虚拟地址,以便访问 if (mdesc->fixup)//调用at91rm9200_fixup()修正函数,分析见后 mdesc->fixup(mdesc, (struct param_struct *)tags, &from, &meminfo); //很明显由bootloader[u-boot-1.1.5]传递到物理地址0x20000100处的参数是tag list结构[gliethttp] if (tags->hdr.tag != ATAG_CORE) convert_to_tag_list(tags); //对于tag list的生成,请参考《浅析setup_arch()函数tag_list的uboot[u-boot]由来》[http://gliethttp.cublog.cn] if (tags->hdr.tag == ATAG_CORE) { if (meminfo.nr_banks != 0)//如果是tag list,那么如果系统已经创建了默认的meminfo.nr_banks squash_mem_tags(tags);//那么使用squash_mem_tags失效所有ATAG_MEM初始化的东东为ATAG_NONE,tag->hdr.size不变 parse_tags(tags); } if (meminfo.nr_banks == 0) {//如果tag list中没有传递ATAG_MEM参数,那么采用编译时的默认配置值 meminfo.nr_banks = 1; meminfo.bank[0].start = PHYS_OFFSET;//0x20000000 meminfo.bank[0].size = MEM_SIZE;//32M } //_text,_etext,_edata,_end参见arch/arm/vmlinux-armv.lds.in链接脚本 init_mm.start_code = (unsigned long) &_text; init_mm.end_code = (unsigned long) &_etext; init_mm.end_data = (unsigned long) &_edata; init_mm.brk = (unsigned long) &_end; memcpy(saved_command_line, from, COMMAND_LINE_SIZE); saved_command_line[COMMAND_LINE_SIZE-1] = '\0';//追0,防止非法字符串越界 //parse_cmdline,主要完成phys_initrd_start,phys_initrd_size和mem的解析,并将*cmdline_p=command_line全局量 parse_cmdline(&meminfo, cmdline_p, from); //将kernel自身和位图管理页占用的页对应的页位图置1,标识相应页已被占用 //将initrd占用的页对应的页位图置1,标识相应页已被占用[gliethttp] bootmem_init(&meminfo); //清空页目录项,建立at91rm9200中断向量表空间和io寄存器空间从虚拟地址到物理地址的映射表 //建立map位图和page页管理空间,以及free_area.map位图管理空间等 paging_init(&meminfo, mdesc); request_standard_resources(&meminfo, mdesc);//登记注册所有需要登记注册的cpu总线上的设备实体 init_arch_irq = mdesc->init_irq;//中断初始化函数指针 #ifdef CONFIG_VT #if defined(CONFIG_VGA_CONSOLE) conswitchp = &vga_con;//显示设备指针conswitchp指向vga_con设备 #elif defined(CONFIG_DUMMY_CONSOLE)//frambuffer选中后,就会使用dummy_con设备 conswitchp = &dummy_con;//显示设备指针conswitchp指向dummy_con设备 #endif #endif } //2.arch/arm/kernel/Process.c->reboot_setup() static char reboot_mode = 'h'; int __init reboot_setup(char *str) { //reboot_mode将在machine_restart()系统重启时arch_reset()使用 reboot_mode = str[0];//reboot_mode='s'; return 1; } //3.arch/arm/mach-at91rm9200/Core.c->at91rm9200_fixup static void __init at91rm9200_fixup(struct machine_desc *desc, struct param_struct *unused, char **cmdline, struct meminfo *mi) { #ifdef CONFIG_BLK_DEV_INITRD//CONFIG_BLK_DEV_INITRD = 1 //设置根目录为ramdisk ROOT_DEV = MKDEV(RAMDISK_MAJOR, 0);//0x100 //由make menuconfig产生CONFIG_BLK_DEV_RAM_SIZE = 15360k = 15M setup_ramdisk(1, 0, 0, CONFIG_BLK_DEV_RAM_SIZE); // setup_initrd(0xc0100000, 3*1024*1024); #endif } void __init setup_ramdisk(int doload, int prompt, int image_start, unsigned int rd_sz) { #ifdef CONFIG_BLK_DEV_RAM extern int rd_size, rd_image_start, rd_prompt, rd_doload; rd_image_start = image_start; rd_prompt = prompt; rd_doload = doload; if (rd_sz) rd_size = rd_sz;//15M #endif } //4.解析tag list中各个元素,进而改变内核全局量,来影响内核 //arch/arm/kernel/Setup.c->parse_tags() static void __init parse_tags(const struct tag *t) { for (; t->hdr.size; t = tag_next(t)) if (!parse_tag(t))//解析该t printk(KERN_WARNING "Ignoring unrecognised tag 0x%08x\n", t->hdr.tag); } //5.arch/arm/kernel/Setup.c->parse_tag() static int __init parse_tag(const struct tag *tag) { extern struct tagtable __tagtable_begin, __tagtable_end; struct tagtable *t; for (t = &__tagtable_begin; t < &__tagtable_end; t++) if (tag->hdr.tag == t->tag) { t->parse(tag); break; } return t < &__tagtable_end;//找到匹配项,1;否则0 } //arch/arm/vmlinux-armv.lds.in链接脚本中有如下定以 //... //__tagtable_begin = .; //*(.taglist) //__tagtable_end = .; //... //在include/asm-arm/Setup.h中有如下定义 #define __tag __attribute__((unused, __section__(".taglist"))) #define __tagtable(tag, fn) \ static struct tagtable __tagtable_##fn __tag = { tag, fn } __tagtable(ATAG_CORE, parse_tag_core);//ATAG_CORE解析函数parse_tag_core __tagtable(ATAG_MEM, parse_tag_mem32);//ATAG_MEM解析函数parse_tag_mem32 __tagtable(ATAG_RAMDISK, parse_tag_ramdisk);//ATAG_RAMDISK解析函数parse_tag_ramdisk __tagtable(ATAG_INITRD, parse_tag_initrd);//ATAG_INITRD解析函数parse_tag_initrd __tagtable(ATAG_SERIAL, parse_tag_serialnr);//ATAG_SERIAL解析函数parse_tag_serialnr __tagtable(ATAG_CMDLINE, parse_tag_cmdline);//ATAG_CMDLINE解析函数parse_tag_cmdline ......等

浅析armlinux-setup_arch()->bootmem_init()函数4

浅析armlinux-setup_arch()->bootmem_init()函数4 文章来源:http://gliethttp.cublog.cn 建议首先参考《浅析armlinux2_4_19启动程序[head-armv.s文件]》[http://gliethttp.cublog.cn]

//---------------------------------------- //1.arch/arm/mm/Init.c->bootmem_init() void __init bootmem_init(struct meminfo *mi) { struct node_info node_info[NR_NODES], *np = node_info; unsigned int bootmap_pages, bootmap_pfn, map_pg; int node, initrd_node; //计算为了管理所有mem内存,需管理位图占据页数目bootmap_pages,np中存储mem对应的页帧号 bootmap_pages = find_memend_and_nodes(mi, np); //查找存放位图管理页的物理页帧号,实际是存放到_end后的后续页中 bootmap_pfn = find_bootmap_pfn(0, mi, bootmap_pages); //检查initrd的合法性,同时将initrd所在内存bank的node返回给initrd_node initrd_node = check_initrd(mi); map_pg = bootmap_pfn;//位图页帧号 np += numnodes - 1; for (node = numnodes - 1; node >= 0; node--, np--) { /* * If there are no pages in this node, ignore it. * Note that node 0 must always have some pages. */ if (np->end == 0) { if (node == 0) BUG(); continue; } //将map_pg开始的位图管理空间全部置0xff init_bootmem_node(NODE_DATA(node), map_pg, np->start, np->end); //释放虚拟地址node_bootmem_map开始的位图管理的所有页,使相应页可用[gliethttp] free_bootmem_node_bank(node, mi); map_pg += np->bootmap_pages; /* * If this is node 0, we need to reserve some areas ASAP - * we may use bootmem on node 0 to setup the other nodes. */ if (node == 0)//我的at91rm9200开发板仅仅有一个node=0 //将kernel自身和位图管理页占用的页对应的页位图置1,标识相应页已被占用 reserve_node_zero(bootmap_pfn, bootmap_pages); } #ifdef CONFIG_BLK_DEV_INITRD//在我的at91rm9200开发板中,initrd是开启的 //并且phys_initrd_start=0x21100000 //phys_initrd_size=6000000=0x5B8D80=5.73M //initrd_node=0; if (phys_initrd_size && initrd_node >= 0) { //将initrd占用的页对应的页位图置1,标识相应页已被占用 reserve_bootmem_node(NODE_DATA(initrd_node), phys_initrd_start, phys_initrd_size); initrd_start = __phys_to_virt(phys_initrd_start);//转成虚拟地址 initrd_end = initrd_start + phys_initrd_size; } #endif if (map_pg != bootmap_pfn + bootmap_pages)//保证所有bootmap都已经被遍历 BUG(); } //---------------------------------------- //2.arch/arm/mm/Init.c->find_memend_and_nodes() static unsigned int __init find_memend_and_nodes(struct meminfo *mi, struct node_info *np) {unsigned int i, bootmem_pages = 0, memend_pfn = 0; for (i = 0; i < NR_NODES; i++) {//默认失效 np[i].start = -1U; np[i].end = 0; np[i].bootmap_pages = 0; } for (i = 0; i < mi->nr_banks; i++) { unsigned long start, end; int node; if (mi->bank[i].size == 0) { mi->bank[i].node = -1;//该bank的node无效-1 continue; } node = mi->bank[i].node;//at91rm9200dk中mem连续node=0 if (node >= numnodes) { numnodes = node + 1; if (numnodes > NR_NODES) BUG(); } //获取当前bank的pfns //#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)//页边界对齐 //define O_PFN_UP(x) (PAGE_ALIGN(x) >> PAGE_SHIFT) start = O_PFN_UP(mi->bank[i].start);//获取该bank.start对应物理页帧号 //同理,//获取该bank.end对应物理页帧号 end = O_PFN_DOWN(mi->bank[i].start + mi->bank[i].size); if (np[node].start > start) np[node].start = start;//存储 if (np[node].end < end) np[node].end = end;//存储 if (memend_pfn < end) memend_pfn = end; } for (i = 0; i < numnodes; i++) { if (np[i].end == 0) continue; //bootmem_bootmap_pages计算pages个页需要多少个页来存储其位图管理信息 np[i].bootmap_pages = bootmem_bootmap_pages(np[i].end - np[i].start); bootmem_pages += np[i].bootmap_pages;//累计位图管理信息页总数 } /* * This doesn't seem to be used by the Linux memory * manager any more. If we can get rid of it, we * also get rid of some of the stuff above as well. */ max_low_pfn = memend_pfn - O_PFN_DOWN(PHYS_OFFSET); // max_pfn = memend_pfn - O_PFN_DOWN(PHYS_OFFSET); mi->end = memend_pfn << PAGE_SHIFT;//所管理的物理内存结束地址 return bootmem_pages; } //---------------------------------------- //3.mm/Bootmem.c->bootmem_bootmap_pages() //计算pages个页需要多少个页来存储其位图管理信息 unsigned long __init bootmem_bootmap_pages (unsigned long pages) {unsigned long mapsize; mapsize = (pages+7)/8;//所需8bits个数 mapsize = (mapsize + ~PAGE_MASK) & PAGE_MASK;//mapsize个字节页对齐 mapsize >>= PAGE_SHIFT;//mapsize个字节对应页数目 return mapsize; } //---------------------------------------- //4.arch/arm/mm/Init.c->find_bootmap_pfn() //查找存放位图管理页的物理页帧号-init_mm.brk static unsigned int __init find_bootmap_pfn(int node, struct meminfo *mi, unsigned int bootmap_pages) {unsigned int start_pfn, bank, bootmap_pfn; start_pfn = V_PFN_UP(&_end);//将_end虚拟内存转换为对应的物理页帧号 bootmap_pfn = 0; for (bank = 0; bank < mi->nr_banks; bank ++) { unsigned int start, end; if (mi->bank[bank].node != node) continue; start = O_PFN_UP(mi->bank[bank]

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