[GitHub] [incubator-nuttx] gustavonihei commented on pull request #4699: arch:cache: add lock & unlock feature

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gustavonihei commented on pull request #4699:
URL: https://github.com/apache/incubator-nuttx/pull/4699#issuecomment-948844412


   > @gustavonihei I think lock_icache have two ways. One is setup transaction the line from memory now, the second is wait the memory be addressed by code, and the lock. I don't think the second is `prefetch`. What's you advice?
   
   Sorry, let me see if I correctly followed your point.
   I understand that the `IPFL` instruction from the Xtensa LX6 ISA prefetches and loads a instruction cache line. Although other ISAs may not implement a similar do-it-all mnemonic, we may still intend `lock_icache` to implement this behavior.
   Looking for some other examples, the [application notes for the Freescale/NXP e300 core](https://www.nxp.com/docs/en/application-note/AN2129.pdf) defines the prefetch of instruction and data as part of the locking procedure (see chapter 2), although not in a singular mnemonic.
   This `lock_icache` proposal may not be most generic, I think it is a good starting point, which may be adapted once other ISAs get it implemented.


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