[IMX6Q]fastboot下载u-boot.bin失败提示太大原因

u-boot版本: v2009.08

在调试其他功能时增加了u-boot.bin容量到1M，使用fastboot download时提示：

sending 'bootloader' (1191 KB)...
OKAY [  1.062s]
writing 'bootloader'...
FAILED (remote: image too large for partition)
finished. total time: 1.098s

但是分区的时候是预留蛮大空间的：

# partition size in MB
BOOTLOAD_RESERVE=8

只能先查找出现error log的地方, uboot-imx/common/cmd_fastboot.c

static int rx_handler (const unsigned char *buffer, unsigned int buffer_size)
{
......
				else if ((download_bytes >
					   (ptn->length * MMC_SATA_BLOCK_SIZE)) &&
						!(ptn->flags & FASTBOOT_PTENTRY_FLAGS_WRITE_ENV)) {
					printf("Image too large for the partition\n");
					sprintf(response, "FAILimage too large for partition");
				} else if (ptn->flags & FASTBOOT_PTENTRY_FLAGS_WRITE_ENV) {
......
}

download_bytes是要download的size,

ptn->length应该就是u-boot分区的大小了，以MMC_SATA_BLOCK_SIZE为单位。

那么ptn->length是什么时候得到的，看fastboot_init():

fastboot_init -> fastboot_init_mmc_sata_ptable

uboot-imx/drivers/fastboot/fastboot.c

static int fastboot_init_mmc_sata_ptable(void)
{
......
	/*以下操作是保存分区表信息到ptable中*/
	memset((char *)ptable, 0,
		    sizeof(fastboot_ptentry) * (PTN_RECOVERY_INDEX + 1));
	/* MBR */
	/*头一个分区放MBR*/
	strcpy(ptable[PTN_MBR_INDEX].name, "mbr");
	ptable[PTN_MBR_INDEX].start = ANDROID_MBR_OFFSET / dev_desc->blksz;
	ptable[PTN_MBR_INDEX].length = ANDROID_MBR_SIZE / dev_desc->blksz;
	ptable[PTN_MBR_INDEX].partition_id = user_partition;
	/* Bootloader */
	/*保存bootloader信息，也就是u-boot信息*/
	strcpy(ptable[PTN_BOOTLOADER_INDEX].name, "bootloader");
	ptable[PTN_BOOTLOADER_INDEX].start =
				ANDROID_BOOTLOADER_OFFSET / dev_desc->blksz;
	ptable[PTN_BOOTLOADER_INDEX].length =
				 ANDROID_BOOTLOADER_SIZE / dev_desc->blksz;
	ptable[PTN_BOOTLOADER_INDEX].partition_id = boot_partition;
	/*从MBR中读取boot, recovery, system分区的信息并保存*/
	setup_ptable_mmc_partition(PTN_KERNEL_INDEX,
				   CONFIG_ANDROID_BOOT_PARTITION_MMC,
				   user_partition, "boot", dev_desc, ptable);
	setup_ptable_mmc_partition(PTN_RECOVERY_INDEX,
				   CONFIG_ANDROID_RECOVERY_PARTITION_MMC,
				   user_partition,
				   "recovery", dev_desc, ptable);
	setup_ptable_mmc_partition(PTN_SYSTEM_INDEX,
				   CONFIG_ANDROID_SYSTEM_PARTITION_MMC,
				   user_partition,
				   "system", dev_desc, ptable);
	/*全部添加到ptable中*/
	for (i = 0; i <= PTN_RECOVERY_INDEX; i++)
		fastboot_flash_add_ptn(&ptable[i]);

	return 0;
}

ANDROID_BOOTLOADER_OFFSET:

#define ANDROID_BOOTLOADER_SIZE	    0xFFC00

所以原因就在于u-boot.bin的size是在u-boot写死了，而不是从MBR中读取的，只要修改此值就可以了。

为什么不能按照读取boot分区那样操作呢？

因为在分区表里并没有保存bootloader的信息，所以MBR和u-boot只能在u-boot中写死了。