On 2024-10-14 22:26, Alex Shumsky wrote:

Increase rng-seed size to make Linux happy and initialize rng pool instantly. Linux 5.19+ requires 32 bytes of entropy to initialize random pool, but u-boot currently provides only 8 bytes. Linux 5.18 and probably some vesrions before it used to require 64 bytes. Bump min value to 64 bytes to be on a safe side.

Boot with 8 byte rng-seed (Linux 6.11): # dmesg | grep crng [ 12.089286] random: crng init done Boot with 32 byte rng-seed (Linux 6.11): # dmesg | grep crng [ 0.000000] random: crng init done

Linux source references: https://github.com/torvalds/linux/blob/7234e2ea0edd00bfb6bb2159e55878c19885c... https://elixir.bootlin.com/linux/v5.18/source/drivers/char/random.c#L236 https://elixir.bootlin.com/linux/v5.19/source/drivers/char/random.c#L551

Signed-off-by: Alex Shumsky alexthreed@gmail.com Fixes: d2048bafae40 ("rockchip: board: Add board_rng_seed() for all Rockchip devices")

Looking good to me, with some additional remarks below.

Reviewed-by: Dragan Simic dsimic@manjaro.org

---

Changes in v3:

• reword warning
• increase default rng_seed_size to support older linux as well
• reword commit message

Changes in v2:

• add env config knob rng_seed_size
• add warning for small rng_seed_size
• 12-character commit SHA in Fixes

arch/arm/mach-rockchip/board.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-rockchip/board.c b/arch/arm/mach-rockchip/board.c index 3fadf7e412..9ff1567fb1 100644 --- a/arch/arm/mach-rockchip/board.c +++ b/arch/arm/mach-rockchip/board.c @@ -472,9 +472,16 @@ __weak int misc_init_r(void) __weak int board_rng_seed(struct abuf *buf) { struct udevice *dev;

• size_t len = 0x8;

• ulong len = env_get_ulong("rng_seed_size", 10, 64); u64 *data;

• if (len < 64) {

• // rng_seed_size should be at least 32 bytes for Linux 5.19+, or 64 
  

for

• // older Linux'es
  

s/Linux'es/Linux kernel versions/ or s/Linux'es/Linux versions/

... and possibly break the comment after the comma, for improved readability.

• log_warning("Value for rng_seed_size too low (%lu) and likely
  

insufficient for the Linux RNG initialization\n",

• 	    len);
  

• }
• data = malloc(len); if (!data) { printf("Out of memory\n");