最近在研究ARM-China发布的STAR-CPU,关于TCM章节有点不是很理解,AHBT是外部访问TCM的AHB-slave总线,一般来说是DMA,这里introduce dependency是什么意思? The processor does not support AHBT transactions that are directly dependent on software memory transactions. This means that the system must not introduce any dependencies where a software memory access cannot complete until a corresponding AHBT transaction completes . Loopback from processor master ports on to the AHBT are not supported because this might cause deadlock (Loopback arrangements should not be required. The processor has higher bandwidth to TCM than the AHBT interface .This means directly transferring data to and from TCM should be faster than through the AHBT interface )
This restriction does not preclude arrangements where software memory-mapped accesses are used . On the S-AHB for example, to request an external agent to perform transactions on the AHBT interface. In this case do not introduce dependency in the system between the control access that initiates the transaction and the transaction itself.