setup_arch - 嵌入式

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].start);
end = O_PFN_DOWN(mi->bank[bank].size +
mi->bank[bank].start);
if (end < start_pfn)
continue;
if (start < start_pfn)
start = start_pfn;//_end对应init_mm.brk临界点
if (end <= start)
continue;
if (end - start >= bootmap_pages) {
bootmap_pfn = start;//从init_mm.brk开始存放位图管理页
break;
}
}
if (bootmap_pfn == 0)
BUG();
return bootmap_pfn;//ok[gliethttp]
}
//----------------------------------------
//5.arch/arm/mm/Init.c->check_initrd()
//检查initrd的合法性
static int __init check_initrd(struct meminfo *mi)
{
int initrd_node = -2;
unsigned long end = phys_initrd_start + phys_initrd_size;
#ifdef CONFIG_BLK_DEV_INITRD
/*
* Make sure that the initrd is within a valid area of
* memory.
*/
if (phys_initrd_size) {
unsigned int i;
initrd_node = -1;
for (i = 0; i < mi->nr_banks; i++) {
unsigned long bank_end;
bank_end = mi->bank[i].start + mi->bank[i].size;
if (mi->bank[i].start <= phys_initrd_start &&
end <= bank_end)
initrd_node = mi->bank[i].node;
}
}
if (initrd_node == -1) {
printk(KERN_ERR "initrd (0x%08lx - 0x%08lx) extends beyond "
"physical memory - disabling initrd\n",
phys_initrd_start, end);
phys_initrd_start = phys_initrd_size = 0;
}
#endif
return initrd_node;//将initrd所在内存bank对应的node返回
}
//----------------------------------------
//6.mm/Bootmem.c->init_bootmem_node()
unsigned long __init init_bootmem_node (pg_data_t *pgdat, unsigned long freepfn, unsigned long startpfn, unsigned long endpfn)
{
return(init_bootmem_core(pgdat, freepfn, startpfn, endpfn));
}
//mm/Bootmem.c->init_bootmem_core()
static unsigned long __init init_bootmem_core (pg_data_t *pgdat,
unsigned long mapstart, unsigned long start, unsigned long end)
{
bootmem_data_t *bdata = pgdat->bdata;//读取&node_bootmem_data[0]
unsigned long mapsize = ((end - start)+7)/8;
pgdat->node_next = pgdat_list;
pgdat_list = pgdat;
mapsize = (mapsize + (sizeof(long) - 1UL)) & ~(sizeof(long) - 1UL);//4字节对齐
bdata->node_bootmem_map = phys_to_virt(mapstart << PAGE_SHIFT);//位图页帧号转为系统用的虚拟地址
bdata->node_boot_start = (start << PAGE_SHIFT);//本map所处物理内存起始地址
bdata->node_low_pfn = end;//本map所处物理内存结束地址
//用0xff填充map位图页帧后,mapsize个字节数据
//arch/arm/lib/memset.S->memset(),对虚拟地址bdata->node_bootmem_map进行赋值
memset(bdata->node_bootmem_map, 0xff, mapsize);
return mapsize;
}
//----------------------------------------
//7.mm/Bootmem.c->free_bootmem_node_bank()
static inline void free_bootmem_node_bank(int node, struct meminfo *mi)
{
pg_data_t *pgdat = NODE_DATA(node);//读取&node_bootmem_data[0]
int bank;
for (bank = 0; bank < mi->nr_banks; bank++)
if (mi->bank[bank].node == node)
free_bootmem_node(pgdat, mi->bank[bank].start,
mi->bank[bank].size);
}
void __init free_bootmem_node (pg_data_t *pgdat, unsigned long physaddr, unsigned long size)
{
return(free_bootmem_core(pgdat->bdata, physaddr, size));
}
static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)
{
unsigned long i;
unsigned long start;
/*
* round down end of usable mem, partially free pages are
* considered reserved.
*/
unsigned long sidx;
unsigned long eidx = (addr + size - bdata->node_boot_start)/PAGE_SIZE;
unsigned long end = (addr + size)/PAGE_SIZE;
if (!size) BUG();
if (end > bdata->node_low_pfn)//一般相等
BUG();
start = (addr + PAGE_SIZE-1) / PAGE_SIZE;//mem起始物理地址对应的页帧号
sidx = start - (bdata->node_boot_start/PAGE_SIZE);//起始大小
for (i = sidx; i < eidx; i++) {///sidx=0,eidx=size/PAGE_SIZE[gliethttp]
//清0各位图管理位,使相应页可用
//如i=4,那么第4物理页可用,清0bdata->node_bootmem_map[0]的第4位
if (!test_and_clear_bit(i, bdata->node_bootmem_map))//node_bootmem_map位图管理起始虚拟地址
BUG();
}
}
///arch/arm/lib/testclearbit.S->test_and_clear_bit()
ENTRY(test_and_clear_bit)
add r1, r1, r0, lsr #3//获取第r0位,对应字节对应的地址
and r3, r0, #7//获取字节中偏移
mov r0, #1
//include/asm-arm/proc-armv/Assembler.h->save_and_disable_irqs[gliethttp]
//.macro save_and_disable_irqs, oldcpsr, temp
//mrs \oldcpsr, cpsr//
//mov \temp, #I_BIT | MODE_SVC
//msr cpsr_c, \temp
//.endm
save_and_disable_irqs ip, r2//将cpsr保存到ip
ldrb r2, [r1]//取出字节数据
tst r2, r0, lsl r3//先测一次,我感觉没用
bic r2, r2, r0, lsl r3//将r2的第r3位清0,成功清0后Z=0,因为硬件故障未能成功那么Z=1,返回后会halt系统
strb r2, [r1]//存储清0后的结果
restore_irqs ip//恢复cpsr
moveq r0, #0//如果因为硬件故障导致不能清0,那么r0=0;清0失败
RETINSTR(mov,pc,lr)
//----------------------------------------
//8.arch/arm/mm/Init.c->reserve_node_zero()
//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
static __init void reserve_node_zero(unsigned int bootmap_pfn, unsigned int bootmap_pages)
{
pg_data_t *pgdat = NODE_DATA(0);//获取node0的所有物理内存管理单元pgdat
//对于_end和_stext,参考arch/arm/vmlinux-armv.lds.in链接脚本
//_end为init_mm.brk,是kernel最末端地址
//__pa(&_stext)物理地址开始的&_end - &_stext个数据,对应页位图置1标识相应页已被占用
reserve_bootmem_node(pgdat, __pa(&_stext), &_end - &_stext);
#ifdef CONFIG_CPU_32
//将arch/arm/kernel/head-armv.s中4M保留页swapper_pg_dir,我的at91rm9200板子对应的物理地址为0x20004000~0x20008000
//swapper_pg_dir~swapper_pg_dir+4k*4的页对应的页位图置1标识相应页已被占用
//#define PTRS_PER_PGD 4096
reserve_bootmem_node(pgdat, __pa(swapper_pg_dir),
PTRS_PER_PGD * sizeof(pgd_t));
#endif
//将_end即init_mm.brk之后存放node物理页位图的位图管理空间也保护起来
//bootmap_pfn << PAGE_SHIFT~(bootmap_pfn << PAGE_SHIFT)+(bootmap_pages << PAGE_SHIFT)的页对应的页位图置1标识相应页已被占用
reserve_bootmem_node(pgdat, bootmap_pfn << PAGE_SHIFT,
bootmap_pages << PAGE_SHIFT);
//以下代码在at91rm9200dk下均不被编译进vmlinuz
if (machine_is_integrator())//if(0),否则会因为reserve_bootmem_node回环,halt系统
reserve_bootmem_node(pgdat, 0, __pa(swapper_pg_dir));
if (machine_is_archimedes() || machine_is_a5k())
reserve_bootmem_node(pgdat, 0x02000000, 0x00080000);
if (machine_is_edb7211() || machine_is_fortunet())
reserve_bootmem_node(pgdat, 0xc0000000, 0x00020000);
if (machine_is_p720t())
reserve_bootmem_node(pgdat, PHYS_OFFSET, 0x00014000);
#ifdef CONFIG_SA1111//非SA1111
reserve_bootmem_node(pgdat, PHYS_OFFSET, __pa(swapper_pg_dir)-PHYS_OFFSET);
#endif
}
void __init reserve_bootmem_node (pg_data_t *pgdat, unsigned long physaddr, unsigned long size)
{//使pgdat管理的物理内存,physaddr~(physaddr+size)之间的物理内存不可使用--占用保留
//physaddr~(physaddr+size)对应页位图置1标识相应页已被占用
reserve_bootmem_core(pgdat->bdata, physaddr, size);
}
static void __init reserve_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)
{
unsigned long i;
/*
* round up, partially reserved pages are considered
* fully reserved.
*/
//bdata->node_boot_start该bdata对应node物理内存的起始地址
unsigned long sidx = (addr - bdata->node_boot_start)/PAGE_SIZE;//计算addr所处页帧号
unsigned long eidx = (addr + size - bdata->node_boot_start +
PAGE_SIZE-1)/PAGE_SIZE;//计算addr+size对应的页帧号
unsigned long end = (addr + size + PAGE_SIZE-1)/PAGE_SIZE;
if (!size) BUG();
if (sidx < 0)
BUG();
if (eidx < 0)
BUG();
if (sidx >= eidx)//数据回环
BUG();
//bdata->node_low_pfn为本node物理内存的地址上限
if ((addr >> PAGE_SHIFT) >= bdata->node_low_pfn)
BUG();
if (end > bdata->node_low_pfn)
BUG();
//条件符合,那么实行保护措施
//将sidx页到eidx页对应的位图置1,位图置1标识相应页已被占用(保护起来,不被kernel使用)
for (i = sidx; i < eidx; i++)
if (test_and_set_bit(i, bdata->node_bootmem_map))
printk("hm, page %08lx reserved twice.\n", i*PAGE_SIZE);
}
///arch/arm/lib/testclearbit.S->test_and_set_bit()
//ENTRY(test_and_set_bit)
// add r1, r1, r0, lsr #3//获取第r0位对应的字节地址
// and r3, r0, #7//计算处于字节的第几位
// mov r0, #1
// save_and_disable_irqs ip, r2//ip=cpsr
// ldrb r2, [r1]
// tst r2, r0, lsl r3
//orr操作,成功操作后Z=0,因为硬件故障未能成功那么Z=1,返回后会halt系统
// orr r2, r2, r0, lsl r3//将r2中的第r3位置1
// strb r2, [r1]//回写
// restore_irqs ip
// moveq r0, #0
// RETINSTR(mov,pc,lr)
//include/asm-arm/proc-armv/Assembler.h->save_and_disable_irqs[gliethttp]
//.macro save_and_disable_irqs, oldcpsr, temp
//mrs \oldcpsr, cpsr//
//mov \temp, #I_BIT | MODE_SVC
浅析setup_arch()函数tag_list的uboot[u-boot]由来
浅析setup_arch()函数tag_list的uboot[u-boot]由来
文章来源:http://gliethttp.cublog.cn
1.linux中
//------------------------------------------------------
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);
setup_processor();
mdesc = setup_machine(machine_arch_type);
machine_name = mdesc->name;
if (mdesc->soft_reboot)
reboot_setup("s");
if (mdesc->param_offset)
tags = phys_to_virt(mdesc->param_offset);    //tags指向AT91_SDRAM_BASE + 0x100地址,该地址处的tag list由uboot生成
/*
* Do the machine-specific fixups before we parse the
* parameters or tags.
*/
if (mdesc->fixup)
mdesc->fixup(mdesc, (struct param_struct *)tags,
&from, &meminfo);
/*
* If we have the old style parameters, convert them to
* a tag list.
*/
if (tags->hdr.tag != ATAG_CORE)                  //2007-07-05 gliethttp 非tag list需要转换;但是uboot传递的是tag list
convert_to_tag_list(tags);
if (tags->hdr.tag == ATAG_CORE) {
if (meminfo.nr_banks != 0)                  //具体的解析
squash_mem_tags(tags);
parse_tags(tags);
}
if (meminfo.nr_banks == 0) {
meminfo.nr_banks = 1;
meminfo.bank[0].start = PHYS_OFFSET;
meminfo.bank[0].size = MEM_SIZE;
}
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';
parse_cmdline(&meminfo, cmdline_p, from);
bootmem_init(&meminfo);
paging_init(&meminfo, mdesc);
request_standard_resources(&meminfo, mdesc);
/*
* Set up various architecture-specific pointers
*/
init_arch_irq = mdesc->init_irq;
#ifdef CONFIG_VT
#if defined(CONFIG_VGA_CONSOLE)
conswitchp = &vga_con;
#elif defined(CONFIG_DUMMY_CONSOLE)
conswitchp = &dummy_con;
#endif
#endif
}
//------------------------------------------------------
arch/arm/vmlinux-armv.lds.in
__arch_info_begin = .;
*(.arch.info)
__arch_info_end = .;
//------------------------------------------------------
include/asm-arm/mach/Arch.h
#define MACHINE_START(_type,_name)                   \
const struct machine_desc __mach_desc_##_type        \
__attribute__((__section__(".arch.info"))) = {      \
.nr        = MACH_TYPE_##_type,                  \
.name        = _name,
#define MAINTAINER(n)
#define BOOT_MEM(_pram,_pio,_vio)                    \
.phys_ram    = _pram,                            \
.phys_io    = _pio,                              \
.io_pg_offst    = ((_vio)>>18)&0xfffc,
#define BOOT_PARAMS(_params)                         \
.param_offset    = _params,
#define VIDEO(_start,_end)                           \
.video_start    = _start,                        \
.video_end    = _end,
#define DISABLE_PARPORT(_n)                          \
.reserve_lp##_n    = 1,
#define BROKEN_HLT /* unused */
#define SOFT_REBOOT                                  \
.soft_reboot    = 1,
#define FIXUP(_func)                                 \
.fixup        = _func,
#define MAPIO(_func)                                 \
.map_io        = _func,
#define INITIRQ(_func)                               \
.init_irq    = _func,
#define MACHINE_END                                  \
};
//------------------------------------------------------
arch/arm/mach-at91rm9200/Core.c
MACHINE_START(AT91RM9200, "ATMEL AT91RM9200")
MAINTAINER("SAN People / ATMEL")
BOOT_MEM(AT91_SDRAM_BASE, AT91C_BASE_SYS, AT91C_VA_BASE_SYS)
BOOT_PARAMS(AT91_SDRAM_BASE + 0x100)
FIXUP(at91rm9200_fixup)
MAPIO(at91rm9200_map_io)
INITIRQ(at91rm9200_init_irq)
MACHINE_END
//------------------------------------------------------
arch/arm/mach-at91rm9200/Core.c->at91rm9200_fixup()
将ramdisk设为根文档系统
static void __init at91rm9200_fixup(struct machine_desc *desc, struct param_struct *unused,
char **cmdline, struct meminfo *mi)
{
#ifdef CONFIG_BLK_DEV_INITRD
ROOT_DEV = MKDEV(RAMDISK_MAJOR, 0);
setup_ramdisk(1, 0, 0, CONFIG_BLK_DEV_RAM_SIZE);
//    setup_initrd(0xc0100000, 3*1024*1024);
#endif
}
2.uboot中
//------------------------------------------------------
u-boot的include/asm-arm/setup.h定义了struct tag结构体
u-boot的lib_arm/armlinux.c->do_bootm_linux()
->setup_start_tag()
->setup_serial_tag()
->setup_revision_tag()
->setup_memory_tags()
->setup_commandline_tag()
->setup_initrd_tag()
->setup_videolfb_tag()
->setup_end_tag()
//------------------------------------------------------
其中u-boot的setup_start_tag会将bd->bi_boot_params传给params
static void setup_start_tag (bd_t *bd)
{
params = (struct tag *) bd->bi_boot_params;
params->hdr.tag = ATAG_CORE;
params->hdr.size = tag_size (tag_core);
params->u.core.flags = 0;
params->u.core.pagesize = 0;
params->u.core.rootdev = 0;
params = tag_next (params);
}
在board/at91rm9200dk/at91rm9200dk.c->board_init()函数中定义了bd->bi_boot_params的初始值gd->bd->bi_boot_params = PHYS_SDRAM +0x100;所以这就刚好和linux中arch/arm/mach-at91rm9200/Core.c的BOOT_PARAMS(AT91_SDRAM_BASE + 0x100)对应起来了。