Von neumann or Modified Harvard Architecture

124 views

Skip to first unread message

AKV

unread,

Dec 7, 2016, 9:06:06 AM12/7/16

to riscv-boom

Hi Christopher,

I have doubt about cache implementation. We have a separate Instruction Cache & Data Cache in boom, so is it Harvard Architecture or its von neumann ?
BOOM uses the Rocket non-blocking cache ("Hellacache"). Is Instruction cache is read only or a program can modify instructions also?
Please guide me where i can get more info about cache implementation in boom?

Warm Regards

AKV

Christopher Celio

unread,

Dec 7, 2016, 3:24:28 PM12/7/16

to riscv-boom

If you execute self-modifying code (you modify instructions), you must execute a fence.i in RISC-V for those changes to become visible to the instruction stream.

Fence.i in rocket/boom performs an icache flush. That will require the icache to go and fetch the new instructions. The icache does NOT snoop the dcache.

https://ccelio.github.io/riscv-boom-doc should have information like this. If it doesn't, submit an issue on its github page and I'll try to address it.