rockchip: board: Increase rng-seed size to make it sufficient for modern Linux
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 versions 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://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/char/random.c?h=v5.19#n551
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/char/random.c?h=v5.18#n236
Signed-off-by: Alex Shumsky <alexthreed@gmail.com>
Fixes: d2048bafae40 ("rockchip: board: Add board_rng_seed() for all Rockchip devices")
Reviewed-by: Dragan Simic <dsimic@manjaro.org>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/mach-rockchip/board.c b/arch/arm/mach-rockchip/board.c
index 3fadf7e..75d6693 100644
--- a/arch/arm/mach-rockchip/board.c
+++ b/arch/arm/mach-rockchip/board.c
@@ -472,9 +472,18 @@
__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 kernel versions
+ */
+ log_warning("Value for rng_seed_size (%lu) too low, Linux kernel RNG may fail to initialize early\n",
+ len);
+ }
+
data = malloc(len);
if (!data) {
printf("Out of memory\n");