工程调试程序出现No source available for "0x0"

[tr]单步调试工程，在一个C文件的最后执行完    IntEnable(C674X_MASK_INT4); IntEnable(C674X_MASK_INT5);  IntGlobalEnable();
    IntEnable(C674X_MASK_NMI);后出现No source available for "0x0" ，而且Disassembly窗体中出现：
00000000:   ???? Memory map prevented reading 0x00000000 [code=0x20000]
00000004:   ???? Memory map prevented reading 0x00000004 [code=0x20000]
00000008:   ???? Memory map prevented reading 0x00000008 [code=0x20000]
0000000c:   ???? Memory map prevented reading 0x0000000C [code=0x20000]
00000010:   ???? Memory map prevented reading 0x00000010 [code=0x20000]
00000014:   ???? Memory map prevented reading 0x00000014 [code=0x20000]
00000018:   ???? Memory map prevented reading 0x00000018 [code=0x20000]
0000001c:   ???? Memory map prevented reading 0x0000001C [code=0x20000]
00000020:   ???? Memory map prevented reading 0x00000020 [code=0x20000]
00000024:   ???? Memory map prevented reading 0x00000024 [code=0x20000]
..............

不清楚这个是什么问题？？？？



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