uboot中给内核传入分区的参数

uboot中给内核传入分区的参数

在uboot 环境变量如何进行配置分区？？

在uboot源码cmd/mtdparts.c中 提供工了这样一段注释

* Three environment variables are used by the parsing routines:** 'partition' - keeps current partition identifier** partition  := <part-id>* <part-id>  := <dev-id>,part_num* 'mtdids' - linux kernel mtd device id <-> u-boot device id mapping** mtdids=<idmap>[,<idmap>,...]** <idmap>    := <dev-id>=<mtd-id>* <dev-id>   := 'nand'|'nor'|'onenand'<dev-num>* <dev-num>  := mtd device number, 0...* <mtd-id>   := unique device tag used by linux kernel to find mtd device (mtd->name)*** 'mtdparts' - partition list** mtdparts=mtdparts=<mtd-def>[;<mtd-def>...]** <mtd-def>  := <mtd-id>:<part-def>[,<part-def>...]* <mtd-id>   := unique device tag used by linux kernel to find mtd device (mtd->name)* <part-def> := <size>[@<offset>][<name>][<ro-flag>]* <size>     := standard linux memsize OR '-' to denote all remaining space* <offset>   := partition start offset within the device* <name>     := '(' NAME ')'* <ro-flag>  := when set to 'ro' makes partition read-only (not used, passed to kernel)** Notes:* - each <mtd-id> used in mtdparts must albo exist in 'mtddis' mapping* - if the above variables are not set defaults for a given target are used** Examples:** 1 NOR Flash, with 1 single writable partition:* mtdids=nor0=edb7312-nor* mtdparts=mtdparts=edb7312-nor:-** 1 NOR Flash with 2 partitions, 1 NAND with one* mtdids=nor0=edb7312-nor,nand0=edb7312-nand* mtdparts=mtdparts=edb7312-nor:256k(ARMboot)ro,-(root);edb7312-nand:-(home)

这么看除了Examples： 能大概看懂其他的也没看懂啥；

给个我单板的实例看下

ubi_mtd=setenv mtdids "nor0=spi0.0";

setenv mtdparts "mtdparts=spi0.0:4M(bootloader),6M(linux.ub),6M(rootfs),10M(fpga),6M(bspom),4M(bootloader-1),6M(linux.ub-1),6M(rootfs-1),10M(fpga-1),6M(bspom-1),64M(data)"

ubi_mtd=setenv mtdids "nor0=spi0.0";setenv mtdparts "mtdparts=spi0.0:4M(bootloader),6M(linux.ub),6M(rootfs),10M(fpga),6M(bspom),4M(bootloader-1),6M(linux.ub-1),6M(rootfs-1),10M(fpga-1),6M(bspom-1),64M(data)"

上面的意思就是：

第一个步: 这只mtdids id 就是 

 * mtdids=<idmap>[,<idmap>,...]
   <idmap>    := <dev-id>=<mtd-id>
  <dev-id>   := 'nand'|'nor'|'onenand'<dev-num>
  <dev-num>  := mtd device number, 0...
  <mtd-id>   := unique device tag used by linux kernel to find mtd device (mtd->name)
 * mtdids=nor0=edb7312-nor,nand0=edb7312-nand
 * mtdparts=mtdparts=edb7312-nor:256k(ARMboot)ro,-(root);edb7312-nand:-(home)

这就能看懂了哈，  mtdids 类型 nand 或者nor  flash 

可以有多个flash，多个配置，需要以逗号分隔配置; 类型使用等号链接

ubi_mtd=setenv mtdids "nor0=spi0.0"; 为啥我这里配置的spi0.0因为在设备树中制定了spi0.0是norflash；

对于每个flash分区的大小和名称在 mtdparts环境变量中指定；

每个flash配置以分号分隔，每个flash项内部分区以逗号分隔；

mtdparts=mtdparts=edb7312-nor:256k(ARMboot)ro,-(root);edb7312-nand:-(home)

举例中这就是有两个flash  ：

edb7312-nor：两个分区  ARMboot 占用256k 剩下的全是 root分区的

edb7312-nand:只有一个分区  home 占用所有空间

uboot中分区初始化函数， 获取环境变量后如果为空(没有定义的话)就使用默认的环境变量；

如果定义了就解析  ， 初始化全局的设备链表  设置参数；

int mtdparts_init(void)
{static int initialized = 0;const char *ids, *parts;const char *current_partition;int ids_changed;char tmp_ep[PARTITION_MAXLEN + 1];char tmp_parts[MTDPARTS_MAXLEN];debug("n---mtdparts_init---n");if (!initialized) {INIT_LIST_HEAD(&mtdids);INIT_LIST_HEAD(&devices);memset(last_ids, 0, sizeof(last_ids));memset(last_parts, 0, sizeof(last_parts));memset(last_partition, 0, sizeof(last_partition));
#if defined(CONFIG_SYS_MTDPARTS_RUNTIME)board_mtdparts_default(&mtdids_default, &mtdparts_default);
#endifuse_defaults = 1;initialized = 1;}/* get variables */ids = env_get("mtdids");   //获取环境变量 mtdids内容parts = env_get_mtdparts(tmp_parts);current_partition = env_get("partition"); //获取环境变量 partition内容/* save it for later parsing, cannot rely on current partition pointer* as 'partition' variable may be updated during init */memset(tmp_parts, 0, sizeof(tmp_parts));memset(tmp_ep, 0, sizeof(tmp_ep));if (current_partition)strncpy(tmp_ep, current_partition, PARTITION_MAXLEN);debug("last_ids  : %sn", last_ids);debug("env_ids   : %sn", ids);debug("last_parts: %sn", last_parts);debug("env_parts : %snn", parts);debug("last_partition : %sn", last_partition);debug("env_partition  : %sn", current_partition);/* if mtdids variable is empty try to use defaults */if (!ids) {if (mtdids_default) {debug("mtdids variable not defined, using defaultn");ids = mtdids_default;env_set("mtdids", (char *)ids);} else {printf("mtdids not defined, no default presentn");return 1;}}if (strlen(ids) > MTDIDS_MAXLEN - 1) {printf("mtdids too long (> %d)n", MTDIDS_MAXLEN);return 1;}/* use defaults when mtdparts variable is not defined* once mtdparts is saved environment, drop use_defaults flag */if (!parts) {if (mtdparts_default && use_defaults) {parts = mtdparts_default;if (env_set("mtdparts", (char *)parts) == 0)use_defaults = 0;} elseprintf("mtdparts variable not set, see 'help mtdparts'n");}if (parts && (strlen(parts) > MTDPARTS_MAXLEN - 1)) {printf("mtdparts too long (> %d)n", MTDPARTS_MAXLEN);return 1;}/* check if we have already parsed those mtdids */if ((last_ids[0] != '') && (strcmp(last_ids, ids) == 0)) {ids_changed = 0;} else {ids_changed = 1;if (parse_mtdids(ids) != 0) {mtd_devices_init();return 1;}/* ok it's good, save new ids */strncpy(last_ids, ids, MTDIDS_MAXLEN);}/* parse partitions if either mtdparts or mtdids were updated */if (parts && ((last_parts[0] == '') || ((strcmp(last_parts, parts) != 0)) || ids_changed)) {if (parse_mtdparts(parts) != 0)return 1;if (list_empty(&devices)) {printf("mtdparts_init: no valid partitionsn");return 1;}/* ok it's good, save new parts */strncpy(last_parts, parts, MTDPARTS_MAXLEN);/* reset first partition from first dev from the list as current */current_mtd_dev = list_, struct mtd_device, link);current_mtd_partnum = 0;current_save();debug("mtdparts_init: current_mtd_dev  = %s%d, current_mtd_partnum = %dn",MTD_DEV_TYPE(current_mtd_dev->id->type),current_mtd_dev->id->num, current_mtd_partnum);}/* mtdparts variable was reset to NULL, delete all devices/partitions */if (!parts && (last_parts[0] != ''))return mtd_devices_init();/* do not process current partition if mtdparts variable is null */if (!parts)return 0;/* is current partition set in environment? if so, use it */if ((tmp_ep[0] != '') && (strcmp(tmp_ep, last_partition) != 0)) {struct part_info *p;struct mtd_device *cdev;u8 pnum;debug("--- getting current partition: %sn", tmp_ep);if (find_dev_and_part(tmp_ep, &cdev, &pnum, &p) == 0) {current_mtd_dev = cdev;current_mtd_partnum = pnum;current_save();}} else if (env_get("partition") == NULL) {debug("no partition variable set, n");current_save();}return 0;
}