帮你查了一下，哈哈 CAUSE Some members of the STM32L4 family have an eratta for the FMC (Flexible Memory Controller) where a read burst access of 9 words or more is not supported by FMC. To prevent burst accesses that are greater than 8 words, a special linker patch was developed to patch certain instructions that result in burst accesses of greater than 8 words. The patch can be applied in most cases with a few exceptions. One of these exceptions is when the instruction to be patched is inside an IT (If-Then) block and is not the last instruction in that block. In this case this warning will be generated. RESOLUTION Since the FMC is only used for external memory, you can ignore this warning if you are only using internal memory. If you are using external memory, make sure your stack is located on-chip. In compiled code, the use of IT blocks can be eliminated by using the --no_conditionalize compiler option. If you are using the DSP library, you will need to rebuild it with the --no_conditionalize compiler option to prevent this warning.This can increase the processing time for DSP functions, so this should only be done for the library used with the STM32L4xx. Also, some math functions such as log10() contain IT blocks that cannot be patched. Since these math functions are not available to be re-built, it may be difficult to eliminate the warning in all cases. In the case of log10(), you can use a similar function, log10f() that does not have the IT block restriction.
