From: Damien Le Moal <damien.lemoal@xxxxxxx> When in M-Mode, we can use the mhartid CSR to get the ID of the running HART. Doing so, direct M-Mode boot without firmware is possible. Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx> --- arch/riscv/kernel/head.S | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S index cb5691d82b0b..e05379fd8b64 100644 --- a/arch/riscv/kernel/head.S +++ b/arch/riscv/kernel/head.S @@ -25,6 +25,14 @@ ENTRY(_start) /* Reset all registers except ra, a0,a1 */ call reset_regs +#ifdef CONFIG_M_MODE + /* + * The hartid in a0 is expected later on, and we have no firmware + * to hand it to us. + */ + csrr a0, mhartid +#endif + /* Load the global pointer */ .option push .option norelax -- 2.20.1
