From: Damien Le Moal <damien.lem...@wdc.com>
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.lem...@wdc.com>
---
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
