android系统移植emmc记录(5)-- fastboot命令分析

本文介绍U-Boot环境下使用Fastboot进行分区配置的方法，包括设置不同分区的地址和大小，以及如何通过Fastboot命令擦除和更新特定分区。

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int do_fastboot (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
{//设置u-boot，kernel，ramdisk ，system，userdata，cache空间地址
if (set_partition_table())
----------------------------------------> // set_partition_table
//主要设置bootloader ramdisk kernel 和fdisk所分的区的起始地址和大小，保存在ptable里面。
/* Bootloader */
strcpy(ptable[pcount].name, "bootloader");
ptable[pcount].start = 0;
ptable[pcount].length = 0;
ptable[pcount].flags = FASTBOOT_PTENTRY_FLAGS_USE_MOVI_CMD;
pcount++;
/* Kernel */
strcpy(ptable[pcount].name, "kernel");
ptable[pcount].start = 0;
ptable[pcount].length = 0;
ptable[pcount].flags = FASTBOOT_PTENTRY_FLAGS_USE_MOVI_CMD;
pcount++;
/* Ramdisk 3M */
strcpy(ptable[pcount].name, "ramdisk");
ptable[pcount].start = 0;
ptable[pcount].length = 0x300000; //3MB,初始值，如果文件大于3M，则会使用文件大小
//写ramdisk的命令类型标志，这里用movi命令来写
ptable[pcount].flags = FASTBOOT_PTENTRY_FLAGS_USE_MOVI_CMD;
pcount++;
-----------------------
/* System */
get_mmc_part_info("0", 2, &start, &count, &pid);
-------------------------
if (pid != 0x83)
goto part_type_error;
strcpy(ptable[pcount].name, "system");
/*
decode_partitionInfo(&mbr[0x1CE], &partInfo);
*block_start = partInfo.block_start;
*block_count = partInfo.block_count;
*part_Id = partInfo.partitionId;
*/ //system 开始的地址
ptable[pcount].start = start * CFG_FASTBOOT_SDMMC_BLOCKSIZE;
//大小，256M
ptable[pcount].length = count * CFG_FASTBOOT_SDMMC_BLOCKSIZE;
//写system数据类型的标志，这里用MMC命令来写
ptable[pcount].flags = FASTBOOT_PTENTRY_FLAGS_USE_MMC_CMD;
pcount++;
/* Data 350M*/
get_mmc_part_info("0", 3, &start, &count, &pid);
if (pid != 0x83)
goto part_type_error;
strcpy(ptable[pcount].name, "userdata");
ptable[pcount].start = start * CFG_FASTBOOT_SDMMC_BLOCKSIZE;
ptable[pcount].length = count * CFG_FASTBOOT_SDMMC_BLOCKSIZE;
ptable[pcount].flags = FASTBOOT_PTENTRY_FLAGS_USE_MMC_CMD;
pcount++;
/* Cache 100 M */
get_mmc_part_info("0", 4, &start, &count, &pid);
if (pid != 0x83)
goto part_type_error;
strcpy(ptable[pcount].name, "cache");
ptable[pcount].start = start * CFG_FASTBOOT_SDMMC_BLOCKSIZE;
ptable[pcount].length = count * CFG_FASTBOOT_SDMMC_BLOCKSIZE;
ptable[pcount].flags = FASTBOOT_PTENTRY_FLAGS_USE_MMC_CMD;
pcount++;
/* fat 剩余空间分区，剩余空间分区格式fat？标志为 0c*/
get_mmc_part_info("0", 1, &start, &count, &pid);
if (pid != 0xc)
goto part_type_error;
strcpy(ptable[pcount].name, "fat");
ptable[pcount].start = start * CFG_FASTBOOT_SDMMC_BLOCKSIZE;
ptable[pcount].length = count * CFG_FASTBOOT_SDMMC_BLOCKSIZE;
ptable[pcount].flags = FASTBOOT_PTENTRY_FLAGS_USE_MMC_CMD;
pcount++;
-------------->
<PRE class=cpp name="code">---------------------------->
//获取fdisk 对system userdata cache分区的大小
int get_mmc_part_info(char *device_name, int part_num, int *block_start, int *block_count, unsigned char *part_Id)
{
int rv;
PartitionInfo partInfo;
unsigned char mbr[512];
//从设备0中读取MBR主分区目录，里面定义了各个分区的信息，和起始，结束扇区
rv = get_mmc_mbr(device_name, mbr);
if(rv !=0)
return -1;
switch(part_num)
{
//剩余容量空间
case 1:
decode_partitionInfo(&mbr[0x1BE], &partInfo);
*block_start = partInfo.block_start;
*block_count = partInfo.block_count;
*part_Id = partInfo.partitionId;
break;
//system 分区表2。fdisk给system分了256M大小
case 2:
decode_partitionInfo(&mbr[0x1CE], &partInfo);
*block_start = partInfo.block_start;
*block_count = partInfo.block_count;
*part_Id = partInfo.partitionId; //83
break;
//userdata 分区
case 3:
decode_partitionInfo(&mbr[0x1DE], &partInfo);
*block_start = partInfo.block_start;
*block_count = partInfo.block_count;
*part_Id = partInfo.partitionId;
break;
//cache分区
case 4:
decode_partitionInfo(&mbr[0x1EE], &partInfo);
*block_start = partInfo.block_start;
*block_count = partInfo.block_count;
*part_Id = partInfo.partitionId;
break;
default:
return -1;
}
return 0;
}

//擦除接口 fastboot erase
if (memcmp(cmdbuf, "erase:", 6) == 0)
{
struct fastboot_ptentry *ptn;
ptn = fastboot_flash_find_ptn(cmdbuf + 6);
if (ptn == 0)
------------------------------------------------------------
//获取fat system userdata cache 分区名字
fastboot_ptentry *fastboot_flash_find_ptn(const char *name)
{
unsigned int n;
for (n = 0; n < pcount; n++)
{
/* Make sure a substring is not accepted */
if (strlen(name) == strlen(ptable[n].name))
{
if (0 == strcmp(ptable[n].name, name))
return ptable + n;
}
}
return 0;
}
-------------------------------------------------------
//只有擦除userdata cache fat 这几个功能，kernel u-boot ramdisk 不能擦除
//其实就是调用ext3format fatmot等格式命令，需要添加system 擦除命令
char run_cmd[80];
status = 1;
if (!strcmp(ptn->name, "sytem"))
{
sprintf(run_cmd, "ext3format mmc 0:2");
status = run_command(run_cmd, 0);
}
Else if (!strcmp(ptn->name, "userdata"))
{
sprintf(run_cmd, "ext3format mmc 0:3");
status = run_command(run_cmd, 0);
}
else if (!strcmp(ptn->name, "cache"))
{
sprintf(run_cmd, "ext3format mmc 0:4");
status = run_command(run_cmd, 0);
}
else if (!strcmp(ptn->name, "fat"))
{
sprintf(run_cmd, "fatformat mmc 0:1");
status = run_command(run_cmd, 0);
}
=======================================================
</PRE>
<P><BR>
</P>
<PRE class=cpp name="code">Flash what was downloaded */
if (memcmp(cmdbuf, "flash:", 6) == 0)
{
if (download_bytes == 0)
{
sprintf(response, "FAILno image downloaded");
ret = 0;
goto send_tx_status;
}
//从此句开始判断 kernel。 ramdisk system,获取ptable
ptn = fastboot_flash_find_ptn(cmdbuf + 6);
----------------------
if ((download_bytes > ptn->length) && (ptn->length != 0) &&
!(ptn->flags & FASTBOOT_PTENTRY_FLAGS_WRITE_ENV))
{ //注意。system写，会出现这个信息。注意检查
//分析，只有当system文件大小小于分区大小时，是不会进入的
sprintf(response, "FAILimage too large for partition");
/* TODO : Improve check for yaffs write */
}
else
{
/* Normal case */
if (write_to_ptn(ptn, (unsigned int)interface.transfer_buffer, download_bytes))
{
printf("flashing '%s' failed\n", ptn->name);
sprintf(response, "FAILfailed to flash partition");
}
else
{
printf("partition '%s' flashed\n", ptn->name);
sprintf(response, "OKAY");
}
}
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