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/7234e2ea0edd00bfb6bb2159e55878c19885ce68/drivers/char/random.c#L632
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 <alexthr...@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 <dsi...@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");
