uboot里怎么对spiflash特定地址进的数据行读取

uboot里怎么对spiflash特定地址进的数据行读取

uboot有个protect 命令，用于设置flash存储器的特定区域为只读模式，或取消只读属性。flash设置为只读模式后，不能被拷贝(cp命令)或者擦除(erase命令)。你的环境变量显然是在保存时就被设置为只读模式，而无法用erase命令擦除。所以你必须顺着如何擦除nand 的protect区域的思路，去查找相应的解决方法。

help输出是这样子的： ? - alias for 'help' base - print or set address offset bootm - boot application image from memory bootp - boot image via network using bootp/tftp protocol cmp - memory compare cp - memory copy crc32 - checksum calculation ext2load- load binary file from a ext2 filesystem ext2ls - list files in a directory (default /) fatinfo - print information about filesystem fatload - load binary file from a dos filesystem fatls - list files in a directory (default /) getinfo - print hardware information go - start application at address 'addr' help - print command description/usage loadb - load binary file over serial line (kermit mode) loady - load binary file over serial line (ymodem mode) loop - infinite loop on address range md - memory display mii - mii utility commands mm - memory modify (auto-incrementing address) mmc - mmc sub system mmcinfo - mmcinfo -- display mmc info mtest - simple ram read/write test mw - memory write (fill) nm - memory modify (constant address) ping - send icmp echo_request to network host printenv- print environment variables rarpboot- boot image via network using rarp/tftp protocol reset - perform reset of the cpu saveenv - save environment variables to persistent storage setenv - set environment variables sf - spi flash sub-system tftp - tftp - download or upload image via network using tftp protocol usb - usb sub-system usbboot - boot from usb device version - print monitor version