With heterogeneous harts config, the PLIC hart topology configuration
string are "M,MS,.." because of the monitor hart #0.

Suggested-by: Fabien Chouteau <chouteau@adacore.com>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
---

Changes in v4: None
Changes in v3: None
Changes in v2: None

 hw/riscv/sifive_u.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/hw/riscv/sifive_u.c b/hw/riscv/sifive_u.c
index a36cd77..284f7a5 100644
--- a/hw/riscv/sifive_u.c
+++ b/hw/riscv/sifive_u.c
@@ -433,10 +433,11 @@ static void riscv_sifive_u_soc_realize(DeviceState *dev, Error **errp)
     plic_hart_config = g_malloc0(plic_hart_config_len);
     for (i = 0; i < ms->smp.cpus; i++) {
         if (i != 0) {
-            strncat(plic_hart_config, ",", plic_hart_config_len);
+            strncat(plic_hart_config, "," SIFIVE_U_PLIC_HART_CONFIG,
+                    plic_hart_config_len);
+        } else {
+            strncat(plic_hart_config, "M", plic_hart_config_len);
         }
-        strncat(plic_hart_config, SIFIVE_U_PLIC_HART_CONFIG,
-                plic_hart_config_len);
         plic_hart_config_len -= (strlen(SIFIVE_U_PLIC_HART_CONFIG) + 1);
     }
 
-- 
2.7.4