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earlephilhower / arduino-pico

Raspberry Pi Pico Arduino core, for all RP2040 and RP2350 boards
GNU Lesser General Public License v2.1
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Feature Request: Change from ARM (M33) to RISC-V (Hazard3) #2359

Closed vslinuxdotnet closed 2 months ago

vslinuxdotnet commented 3 months ago

Hello, Is possible to add a option menu flag, to change from ARM (M33) to RISC-V (Hazard3) ?

EX: cmake -DPICO_PLATFORM=rp2350-arm-s -DPICO_BOARD=pico2 .. cmake -DPICO_PLATFORM=rp2350-riscv -DPICO_BOARD=pico2 ..

Thanks, VS

vslinuxdotnet commented 3 months ago

Seams that will require also the riscv-gnu-toolchain

earlephilhower commented 3 months ago

Yes, a new toolchain is needed to be added and built in pico-quick-toolchain (we have special Newlib configurations to fully support multicore and FreeRTOS, which is not present int any generic build). What's worse, though, is it seems only bleeding-edge GCC 14.1 supports the full Hazard3 ISA, which means a bump to GCC revs...always lots of little gotchas in that.

Then the core itself will need revision to support the new HW in terms of IRQs, DMA, GPIO control. Some may "just work" but for parts not covered by the SDK there will be porting involved...

Hedda commented 3 months ago

Edge case but maybe also consider running mixed mode with one RISC-V core and one ARM Cortex-M33 core which the RP2350 supports? Arm/RISC-V switching is explained in the official datasheet: as "They're selectable at boot time: Each port into the bus fabric can be connected either to an M33 or a Hazard3 via a mux. You can even, if you're feeling obtuse, run with one of each."

earlephilhower commented 2 months ago

See #2491 . Not sure if it will really be part of the core...