I have been creating a basic core management tool which is able to dynamically turn CPU cores on and off using Arm's PSCI CPU_ON and CPU_OFF functions. This worked great on QEMU, however moving onto real hardware (particularly an OdroidC4), turning the core back on didn't work.
When I attempt to turn a core on, it is stuck in the "PENDING" state which can be seen via the AFFINITY_INFO PSCI function. It seems like the entry_point given to CPU_ON is just not being called on the OdroidC4. Below is a code snippet of the function I am trying to get CPU_ON to call. It simply writes into UART, however, I do not see this output.
#define UART_WFIFO 0x00
BEGIN_FUNC(bootstrap_start)
movz x0, #0xff80, LSL #16
movk x0, #0x3000
mov w2, #'\n'
str w2, [x0, #UART_WFIFO]
mov w3, #'B'
str w3, [x0, #UART_WFIFO]
mov w4, #'\n'
str w4, [x0, #UART_WFIFO]
ret
END_FUNC(bootstrap_start)
The bootstrap_start function is located at 0x10_000_000 in physical memory. This all worked on QEMU, but happened to break moving to the OdroidC4. Anybody know why this might be happening or how to debug this if I don't have access to GDB?
