That's really useful info, ta.
Where are these registers documented? I have the espressif tech ref manual for the S3, but that address range is marked as reserved.

Thanks, I should've clicked further. Now I have the assembler source for the cache writeback, but it has revealed another hole (in my knowledge). The assembler source references an ESP32S3 register called EXTMEM_DCACHE_SYNC_ADDR_REG. I cannot find any reference to this in the ESP32 technical manual....

Thanks.
Is there any special library I need to install, as simply including cache.h causes a compiler error (file not found)?

Thanks. That explains what owner means.
Regarding Cache_WriteBack_Addr, what files should be included in my sketch (I'm using Arduino IDE)?

Hi, So, it all started (as a newbie to ESP32 and Arduino IDE) when I found difficulty finding a GFX library for my board (Guition ESP32-S3-4848S040) and what files need to be modified related to the assignment of ESP pins to the LCD interface, and for the initialisation sequence for the ST7701 panel...