一种高效的嵌入式系统固件局部更新方法

为了解决资源紧缺型嵌入式系统(Resource-scarce Embedded System，RSES)在固件更新时所存在的效率低问题，提出了一种高效的固件局部更新(Efficient Local Firmware Update，EL-FU)方法:新的局部固件先由调试器写入内存，然后由驱动程序写入外存中预留的局部更新区域，最后由调试器进行调试. 该方法通过修改操作系统，增加了更新触发、固件更新、目录添加和提醒4个模块(仅增加了约3 KB代码)，实现了不需要使用烧写工具、不需要打包整个固件、仅利用调试器就可以更新局部固件的功能. 测试了在某资源紧缺型的蓝牙音频片上系统(内核为MIPS32 M4K，内存为128 KB)上使用EL-FU方法更新固件后，系统的可靠性和稳定性，并比较了在该系统使用EL-FU方法和传统JDO-FU(JTAG Debugger-based Overall Firmware Update)方法更新固件的效率，同时比较了在该RSES和某资源丰富型嵌入式系统(Resource-rich Embedded System，RRES)更新相同大小固件的效率. 测试结果表明:应用了EL-FU方法的RSES具有可靠性和稳定性；在RSES上采用EL-FU方法的固件更新效率远高于采用JDO-FU方法的；在RSES上使用EL-FU方法更新固件可以克服运算和内存资源少的限制，获得与RRES相近的固件更新效率.

An Efficient Local Firmware Update Method for Embedded System

An efficient local firmware update (EL-FU) method is proposed to solve the problem of low efficiency in firmware updating of resource-scarce embedded system (RSES). A new local firmware is first written into memory by the debugger and written into the local update area reserved in external memory by the driver, and then debugged by the debugger. An update trigger module, a firmware update module, a directory adding module and a reminder module are added to the operating system, which only adds 3K bytes of code to the operating system. The local firmware is updated only by the debugger without using the burning tool and packaging the whole firmware. The reliability and stability of a resource-scarce Bluetooth audio on the chip system (MIPS32 M4K kernel and 128K bytes memory) whose firmware is updated with the EL-FU method, is tested. The efficiency of the proposed EL-FU method and the conventional JDO-FU (JTAG Debugger-based Overall Firmware Update) method to update firmware in the system is compared. At the same time, the efficiency of updating firmware of the same size in the RSES and a resource-rich embedded system (RRES) is compared. As the test results show, the RSES with the EL-FU method is reliable and stable; in the RSES, the firmware update efficiency of the EL-FU method is much higher than that of the JDO-FU method; the RSES can use the EL-FU method to overcome the limitation of less computing and memory resources and achieve the same firmware update efficiency as the RRES.