UBOOT开发的问题1

技术类问题
1.    小弟正在开发烧写UBOOT到NANDFLASH的烧写器代码,硬件环境:TI DAVINCI开发平台.软件环境:montavista linux.bootloader:UBOOT-1.1.3.集成开发环境:CCSv3.2.TI提供了烧写器源码,建立工程,添加源码文件.编译出现如下错误,请教其中原因.谢谢!
----------------------------  practice.pjt - Debug  ----------------------------
[Linking...] "C:\CCStudio_v3.2\C6000\cgtools\bin\cl6x" -@"Debug.lkf"
<Linking>
>> warning: creating output section .far without SECTIONS specification
>> warning: creating output section .switch without SECTIONS specification

undefined                        first referenced
 symbol                              in file
---------                        ----------------
_UART_recvString                 C:\\CCStudio_v3.2\\MyProjects\\practice\\Debug\\debug.obj
_UART_sendHexInt                 C:\\CCStudio_v3.2\\MyProjects\\practice\\Debug\\debug.obj
_UART_recvStringN                C:\\CCStudio_v3.2\\MyProjects\\practice\\Debug\\debug.obj
_UART_sendString                 C:\\CCStudio_v3.2\\MyProjects\\practice\\Debug\\debug.obj
_EXTERNAL_RAM_START              C:\\CCStudio_v3.2\\MyProjects\\practice\\Debug\\device.obj
_EMIFStart                       C:\\CCStudio_v3.2\\MyProjects\\practice\\Debug\\nandwriter.obj
_EXTERNAL_RAM_END                C:\\CCStudio_v3.2\\MyProjects\\practice\\Debug\\util.obj
>>   error: symbol referencing errors - './Debug/practice.out' not built

>> Compilation failure

Build Complete,
  2 Errors, 2 Warnings, 0 Remarks.