场景：自己画的板子，OMAP-L138，通过硬件测试发现：NAND FLASH和网口都有问题，也就是说UBL和U-BOOT都不能烧写到NAND FLASH中，并且不能使用网络服务(TFTP、NFS)。所以考虑用UART启动方式，用“UART Boot Host Utility”这个工具把UBL（AIS格式）下载到Shared RAM空间。接着，按大家所说，应该是UBL从串口读取U-BOOT到DDR空间，并跳转到该地址运行U-BOOT。
问题：用什么工具把U-BOOT下载到DDR空间？
下面是UBL源码从串口读取U-BOOT的相关函数：
static Uint32 LOCAL_recvHeaderAndData(UARTBOOT_HeaderHandle ackHeader)
{
Uint32 error = E_FAIL, recvLen;
// Recv ACK command
error = UART_checkSequence(" ACK", TRUE);
if(error != E_PASS)
{
return E_FAIL;
}
// Get the ACK header elements
error = UART_recvHexData( 4, (Uint32 *) &(ackHeader->magicNum) );
error |= UART_recvHexData( 4, (Uint32 *) &(ackHeader->startAddr) );
error |= UART_recvHexData( 4, (Uint32 *) &(ackHeader->byteCnt) );
error |= UART_checkSequence("0000", FALSE);
if(error != E_PASS)
{
return E_FAIL;
}
// Verify that the data size is appropriate
if((ackHeader->byteCnt == 0) || (ackHeader->byteCnt > APP_IMAGE_SIZE))
{
LOCAL_sendSequence(" BADCNT"); // trailing /0 will come along
return E_FAIL;
}
// Verify application start address is in RAM (lower 16bit of appStartAddr also used
// to hold UBL entry point if this header describes a UBL)
if( (ackHeader->startAddr < DEVICE_DDR2_START_ADDR) || (ackHeader->startAddr > DEVICE_DDR2_END_ADDR) )
{
LOCAL_sendSequence("BADADDR"); // trailing /0 will come along
return E_FAIL;
}
// Send BEGIN command
if (LOCAL_sendSequence(" BEGIN") != E_PASS)
return E_FAIL;
// Receive the data over UART
recvLen = ackHeader->byteCnt;
error = UART_recvStringN((String)(ackHeader->loadAddr), &recvLen, FALSE );
if ( (error != E_PASS) || (recvLen != ackHeader->byteCnt) )
{
DEBUG_printString("\r\nUART Receive Error\r\n");
return E_FAIL;
}
// Return DONE when all data arrives
if ( LOCAL_sendSequence(" DONE") != E_PASS )
return E_FAIL;
return E_PASS;
}
很明显，UBL在从串口接收数据（U-BOOT），那么是谁发给它的呢？
另外，在NAND FLASH 和 网口 都挂掉的情况下，有没有可能移植 kernel 和 文件系统呢？
