[PATCH 2/2] hw/riscv: Don't add empty bootargs to device tree

[Bin Meng <bmeng.cn@gmail.com>]

From: Bin Meng <bin.meng@windriver.com>

Commit 7c28f4da20e5 ("RISC-V: Don't add NULL bootargs to device-tree")
tried to avoid adding *NULL* bootargs to device tree, but unfortunately
the changes were entirely useless, due to MachineState::kernel_cmdline
can't be NULL at all as the default value is given as an empty string.
(see hw/core/machine.c::machine_initfn()).

Note the wording of *NULL* bootargs is wrong. It can't be NULL otherwise
a segfault had already been observed by dereferencing the NULL pointer.
It should be worded as *empty" bootargs.

Fixes: 7c28f4da20e5 ("RISC-V: Don't add NULL bootargs to device-tree")
Signed-off-by: Bin Meng <bin.meng@windriver.com>
---

 hw/riscv/microchip_pfsoc.c | 2 +-
 hw/riscv/sifive_u.c        | 2 +-
 hw/riscv/spike.c           | 2 +-
 hw/riscv/virt.c            | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/hw/riscv/microchip_pfsoc.c b/hw/riscv/microchip_pfsoc.c
index cafd1fc9ae..10a5d0e501 100644
--- a/hw/riscv/microchip_pfsoc.c
+++ b/hw/riscv/microchip_pfsoc.c
@@ -571,7 +571,7 @@ static void microchip_icicle_kit_machine_init(MachineState *machine)
                                   "linux,initrd-end", end);
         }
 
-        if (machine->kernel_cmdline) {
+        if (machine->kernel_cmdline && *machine->kernel_cmdline) {
             qemu_fdt_setprop_string(machine->fdt, "/chosen",
                                     "bootargs", machine->kernel_cmdline);
         }
diff --git a/hw/riscv/sifive_u.c b/hw/riscv/sifive_u.c
index 7fbc7dea42..cc8c7637cb 100644
--- a/hw/riscv/sifive_u.c
+++ b/hw/riscv/sifive_u.c
@@ -511,7 +511,7 @@ static void create_fdt(SiFiveUState *s, const MemMapEntry *memmap,
     g_free(nodename);
 
 update_bootargs:
-    if (cmdline) {
+    if (cmdline && *cmdline) {
         qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
     }
 }
diff --git a/hw/riscv/spike.c b/hw/riscv/spike.c
index 1562b000bb..068ba3493e 100644
--- a/hw/riscv/spike.c
+++ b/hw/riscv/spike.c
@@ -177,7 +177,7 @@ static void create_fdt(SpikeState *s, const MemMapEntry *memmap,
     qemu_fdt_add_subnode(fdt, "/chosen");
     qemu_fdt_setprop_string(fdt, "/chosen", "stdout-path", "/htif");
 
-    if (cmdline) {
+    if (cmdline && *cmdline) {
         qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
     }
 }
diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
index da50cbed43..a628a3abdf 100644
--- a/hw/riscv/virt.c
+++ b/hw/riscv/virt.c
@@ -998,7 +998,7 @@ static void create_fdt(RISCVVirtState *s, const MemMapEntry *memmap,
     create_fdt_flash(s, memmap);
 
 update_bootargs:
-    if (cmdline) {
+    if (cmdline && *cmdline) {
         qemu_fdt_setprop_string(mc->fdt, "/chosen", "bootargs", cmdline);
     }
 }
-- 
2.25.1