arm9_uboot启动内核

我就是我 2023-06-01 06:20 17阅读 0赞

在u-boot-1.1.6/common/main.c中的main\_loop中

s = getenv ("bootcmd");// bootcmd=nand read.jffs2 0x30007FC0 kernel; bootm 0x30007FC0

run_command (s, 0);

![1424785-20190922115004678-160316106.png][]

在u-boot-1.1.6/common/cmd\_nand.c中

if (s != NULL &&
                (!strcmp(s, ".jffs2") || !strcmp(s, ".e") || !strcmp(s, ".i"))) {
                if (read) {
                    /* read */
                    nand_read_options_t opts;
                    memset(&opts, 0, sizeof(opts));
                    opts.buffer = (u_char*) addr;
                    opts.length = size;
                    opts.offset = off;
                    opts.quiet      = quiet;
                    ret = nand_read_opts(nand, &opts);
                }

在u-boot-1.1.6/common/cmd\_bootm.c中image\_header\_t \*hdr = &header;

image\_header\_t \*hdr = &header;

switch (hdr->ih_os) {
        default:            /* handled by (original) Linux case */
        case IH_OS_LINUX:
    #ifdef CONFIG_SILENT_CONSOLE
            fixup_silent_linux();
    #endif
            do_bootm_linux  (cmdtp, flag, argc, argv,
                     addr, len_ptr, verify);
            break;
        case IH_OS_NETBSD:
            do_bootm_netbsd (cmdtp, flag, argc, argv,
                     addr, len_ptr, verify);
            break;

我們知道内核image是由头与内核组成；头在u-boot-1.1.6/include/image.h定义；而内核加载地址0x30008000 再减去**0x30007FC0刚好等于头的大小64;**

#define IH_NMLEN        32    /* Image Name Length        */
    
    /*
     * all data in network byte order (aka natural aka bigendian)
     */
    
    typedef struct image_header {
        uint32_t    ih_magic;    /* Image Header Magic Number    */
        uint32_t    ih_hcrc;    /* Image Header CRC Checksum    */
        uint32_t    ih_time;    /* Image Creation Timestamp    */
        uint32_t    ih_size;    /* Image Data Size        */
        uint32_t    ih_load;    /* Data     Load  Address        */  //加载地址为：0x30008000
        uint32_t    ih_ep;        /* Entry Point Address        */
        uint32_t    ih_dcrc;    /* Image Data CRC Checksum    */
        uint8_t        ih_os;        /* Operating System        */
        uint8_t        ih_arch;    /* CPU architecture        */
        uint8_t        ih_type;    /* Image Type            */
        uint8_t        ih_comp;    /* Compression Type        */
        uint8_t        ih_name[IH_NMLEN];    /* Image Name        */
    } image_header_t;

而do\_bootm\_linux函数在u-boot-1.1.6/lib\_arm/armlinux.c文件中定义

static struct tag \*params;

void (\*theKernel)(int zero, int arch, uint params);

image\_header\_t \*hdr = &header;  
bd\_t \*bd = gd->bd;

char \*commandline = getenv ("bootargs"); //bootargs=noinitrd root=/dev/mtdblock3 init=/linuxrc console=ttySAC0,115200

theKernel = (void (*)(int, int, uint))ntohl(hdr->ih_ep); //头结构里面的内核入口地址

setup\_start\_tag (bd);//设置参数  
setup\_serial\_tag (&params);  
setup\_revision\_tag (&params);  
setup\_memory\_tags (bd);  
setup\_commandline\_tag (bd, commandline);  
setup\_initrd\_tag (bd, initrd\_start, initrd\_end);  
setup\_videolfb\_tag ((gd\_t \*) gd);  
setup\_end\_tag (bd);

cleanup\_before\_linux ();

theKernel (0, bd->bi\_arch\_number, bd->bi\_boot\_params); //启动内核；gd->bd->bi\_arch\_number = MACH\_TYPE\_S3C2440; gd->bd->bi\_boot\_params = 0x30000100

static void setup\_start\_tag (bd\_t \*bd)//随便拎出几个设置函数看一下  
\{  
params = (struct tag \*) bd->bi\_boot\_params; //;//这就是参数保存的起始地址

params->hdr.tag = ATAG\_CORE; //\#define ATAG\_CORE 0x54410001  
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);  
\}

static void setup\_memory\_tags (bd\_t \*bd)  
\{  
int i;

for (i = 0; i < CONFIG\_NR\_DRAM\_BANKS; i++) \{  
params->hdr.tag = ATAG\_MEM; //\#define ATAG\_MEM 0x54410002  
params->hdr.size = tag\_size (tag\_mem32);

params->u.mem.start = bd->bi\_dram\[i\].start; //0x30000000 /\* SDRAM Bank \#1 \*/  
params->u.mem.size = bd->bi\_dram\[i\].size; //0x04000000 /\* 64 MB \*/

params = tag\_next (params);  
\}  
\}

static void setup\_commandline\_tag (bd\_t \*bd, char \*commandline)  
\{  
char \*p;

if (!commandline)  
return;

/\* eat leading white space \*/  
for (p = commandline; \*p == ' '; p++);

/\* skip non-existent command lines so the kernel will still  
\* use its default command line.  
\*/  
if (\*p == '\\0')  
return;

params->hdr.tag = ATAG\_CMDLINE; //\#define ATAG\_CMDLINE 0x54410003  
params->hdr.size =  
(sizeof (struct tag\_header) + strlen (p) + 1 + 4) >> 2;

strcpy (params->u.cmdline.cmdline, p);

params = tag\_next (params);  
\}

static void setup\_end\_tag (bd\_t \*bd)  
\{  
params->hdr.tag = ATAG\_NONE;  
params->hdr.size = 0;  
\}

在u-boot-1.1.6/include/asm/u-boot.h文件中，定义了存储u-boot启动项结构体bd\_t

typedef struct bd_info {
        int            bi_baudrate;    /* serial console baudrate */
        unsigned long    bi_ip_addr;    /* IP Address */
        unsigned char    bi_enetaddr[6]; /* Ethernet adress */
        struct environment_s           *bi_env;
        ulong            bi_arch_number;    /* unique id for this board */
        ulong            bi_boot_params;    /* where this board expects params */
        struct                /* RAM configuration */
        {
        ulong start;
        ulong size;
        }             bi_dram[CONFIG_NR_DRAM_BANKS];
    #ifdef CONFIG_HAS_ETH1
        /* second onboard ethernet port */
        unsigned char   bi_enet1addr[6];
    #endif
    } bd_t;

在u-boot-1.1.6/include/asm-arm/setup.h中定义了u-boot传递给内核的参数的结构体

struct tag {
        struct tag_header hdr;
        union {
            struct tag_core        core;
            struct tag_mem32    mem;
            struct tag_videotext    videotext;
            struct tag_ramdisk    ramdisk;
            struct tag_initrd    initrd;
            struct tag_serialnr    serialnr;
            struct tag_revision    revision;
            struct tag_videolfb    videolfb;
            struct tag_cmdline    cmdline;
    
            /*
             * Acorn specific
             */
            struct tag_acorn    acorn;
    
            /*
             * DC21285 specific
             */
            struct tag_memclk    memclk;
        } u;
    };

struct tag\_header \{  
u32 size;  
u32 tag;  
\};

转载于:https://www.cnblogs.com/lzd626/p/11567001.html

[1424785-20190922115004678-160316106.png]: /images/20230601/c46d269fbedf4b22819dcc9bbbcadbd1.png