gpoulios commented on code in PR #16729:
URL: https://github.com/apache/nuttx/pull/16729#discussion_r2209402819


##########
drivers/misc/optee.c:
##########
@@ -345,6 +346,10 @@ optee_shm_to_page_list(FAR struct optee_shm *shm, FAR 
uintptr_t *list_pa)
       *list_pa = optee_va_to_pa(list) | pgoff;
     }
 
+#ifndef CONFIG_ARCH_USE_MMU

Review Comment:
   It **_is_** a supported configuration, even though uncommon:
   
   1) The document you cite states that in the case of MMU off (emphasis mine):
   > _Unexpected data cache hit behavior is **implementation defined**._
   
   2) Please have a look at the selected answer by the Arm employee 
[here](https://community.arm.com/support-forums/f/architectures-and-processors-forum/8908/a8-keeping-cache-enabled-and-mmu-disabled#:~:text=If%20I%20enable%20the%20L1,Is%20this%20the%20expected%20behavior?)
 (again, emphasis mine):
   > _There is absolutely no point in running without the MMU enabled, **except 
if you are EXTREMELY resource-constrained and can't spare the memory to write 
the tables** (you only need 16KiB, though, for the bare essentials at 1MB and 
16MB granularity)._
   
   Well, in our case, we **_are_** extremely resource constrained (and we've 
found that in NuttX, the tables take up slightly more than 16KiB, but even if 
so, we can't spare those 16KiB).



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