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> Signed-off-by: Christoph Hellwig <hch@xxxxxx> --- 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 e5fa5481aa99..a4c170e41a34 100644 --- a/arch/riscv/kernel/head.S +++ b/arch/riscv/kernel/head.S @@ -18,6 +18,14 @@ ENTRY(_start) csrw CSR_XIE, zero csrw CSR_XIP, zero +#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
