工具：Quartus2.2 SP2
我用SOPC Build了一个名为Minsys系统，并且成功的生成文件Minsys.bsf。用Pll.bsf和Minsys.bsf组成顶层文件wbt.bdf。当编译时出错，错误如下。错误定位在cpu.vhd文件的5501行。顺便说一下，在仿照nios_tutorial中的project做时，出现同样的错误。不知道是怎么回事。
（错误中说undefined entity，可是在cpu.vhd文件中定义了呀。我怀疑是Quartus的问题，crack的呀 ）
> Found 1 design units and 1 entities in source file E:My_designsWBTWBT.bdf
> Found 2 design units and 0 entities in source file E:My_designsWBTaltera_vhdl_support.vhd
> Found 2 design units and 1 entities in source file E:My_designsWBTPLL.vhd
> Found 1 design units and 1 entities in source file D:Alteraquartuslibrariesmegafunctionsaltpll.tdf
> Found 26 design units and 13 entities in source file E:My_designsWBTMinSystem.vhd
> Found 2 design units and 1 entities in source file E:My_designsWBTmul_cpu.vhd
> Found 2 design units and 1 entities in source file E:My_designsWBTmul_cpu_black_box_module.vhd
> Found 1 design units and 1 entities in source file D:Alteraquartuslibrariesmegafunctionslpm_mult.tdf
> Found 1 design units and 1 entities in source file D:Alteraquartuslibrariesmegafunctionsmultcore.tdf
> Found 1 design units and 1 entities in source file D:Alteraquartuslibrariesmegafunctionsmul_boothc.tdf
> Found 1 design units and 1 entities in source file D:Alteraquartuslibrariesmegafunctionsmpar_add.tdf
> Found 1 design units and 1 entities in source file D:Alteraquartuslibrariesmegafunctionslpm_add_sub.tdf
> Found 1 design units and 1 entities in source file D:Alteraquartuslibrariesmegafunctionsaddcore.tdf
> Found 1 design units and 1 entities in source file D:Alteraquartuslibrariesmegafunctionsa_csnbuffer.tdf
> Found 1 design units and 1 entities in source file D:Alteraquartuslibrariesmegafunctionsaltshift.tdf
> Found 4 design units and 2 entities in source file E:My_designsWBTsdram.vhd
> Found 84 design units and 42 entities in source file E:My_designsWBTcpu.vhd
> Node instance cpu_register_bank_a instantiates undefined entity cpu_dpram_module
> Design WBT: Full compilation was unsuccessful. 1 error, 0 warnings
