If the FDT contains /chosen/rng-seed, then the Linux RNG will use it to
initialize early. Set this using the usual guest random number
generation function. This FDT node is part of the DT specification.

Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 hw/rx/rx-gdbsim.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/rx/rx-gdbsim.c b/hw/rx/rx-gdbsim.c
index be147b4bd9..8ffe1b8035 100644
--- a/hw/rx/rx-gdbsim.c
+++ b/hw/rx/rx-gdbsim.c
@@ -19,6 +19,7 @@
 #include "qemu/osdep.h"
 #include "qemu/cutils.h"
 #include "qemu/error-report.h"
+#include "qemu/guest-random.h"
 #include "qapi/error.h"
 #include "hw/loader.h"
 #include "hw/rx/rx62n.h"
@@ -83,6 +84,7 @@ static void rx_gdbsim_init(MachineState *machine)
     MemoryRegion *sysmem = get_system_memory();
     const char *kernel_filename = machine->kernel_filename;
     const char *dtb_filename = machine->dtb;
+    uint8_t rng_seed[32];
 
     if (machine->ram_size < mc->default_ram_size) {
         char *sz = size_to_str(mc->default_ram_size);
@@ -140,6 +142,8 @@ static void rx_gdbsim_init(MachineState *machine)
                 error_report("Couldn't set /chosen/bootargs");
                 exit(1);
             }
+            qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
+            qemu_fdt_setprop(dtb, "/chosen", "rng-seed", rng_seed, sizeof(rng_seed));
             /* DTB is located at the end of SDRAM space. */
             dtb_offset = ROUND_DOWN(machine->ram_size - dtb_size, 16);
             rom_add_blob_fixed("dtb", dtb, dtb_size,
-- 
2.35.1

On Tue, 19 Jul 2022 21:20:33 +0900,
Jason A. Donenfeld wrote:
> 
> If the FDT contains /chosen/rng-seed, then the Linux RNG will use it to
> initialize early. Set this using the usual guest random number
> generation function. This FDT node is part of the DT specification.
> 
> Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
>  hw/rx/rx-gdbsim.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/hw/rx/rx-gdbsim.c b/hw/rx/rx-gdbsim.c
> index be147b4bd9..8ffe1b8035 100644
> --- a/hw/rx/rx-gdbsim.c
> +++ b/hw/rx/rx-gdbsim.c
> @@ -19,6 +19,7 @@
>  #include "qemu/osdep.h"
>  #include "qemu/cutils.h"
>  #include "qemu/error-report.h"
> +#include "qemu/guest-random.h"
>  #include "qapi/error.h"
>  #include "hw/loader.h"
>  #include "hw/rx/rx62n.h"
> @@ -83,6 +84,7 @@ static void rx_gdbsim_init(MachineState *machine)
>      MemoryRegion *sysmem = get_system_memory();
>      const char *kernel_filename = machine->kernel_filename;
>      const char *dtb_filename = machine->dtb;
> +    uint8_t rng_seed[32];
>  
>      if (machine->ram_size < mc->default_ram_size) {
>          char *sz = size_to_str(mc->default_ram_size);
> @@ -140,6 +142,8 @@ static void rx_gdbsim_init(MachineState *machine)
>                  error_report("Couldn't set /chosen/bootargs");
>                  exit(1);
>              }
> +            qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
> +            qemu_fdt_setprop(dtb, "/chosen", "rng-seed", rng_seed, sizeof(rng_seed));
>              /* DTB is located at the end of SDRAM space. */
>              dtb_offset = ROUND_DOWN(machine->ram_size - dtb_size, 16);
>              rom_add_blob_fixed("dtb", dtb, dtb_size,
> -- 
> 2.35.1
> 

Reviewed-by: Yoshinori Sato <ysato@users.sourceforge.jp>

-- 
Yosinori Sato