Hi,
Am 30.08.23 um 12:38 schrieb Thorsten Leemhuis:
/me gets the impression he has to chime in here
On 25.08.23 14:14, Stefan Wahren wrote:
Am 25.08.23 um 13:26 schrieb Jason A. Donenfeld:
On Fri, Aug 25, 2023 at 01:14:55PM +0200, Stefan Wahren wrote:
i didn't find the time to fix the performance regression in bcm2835-rng
which affects Raspberry Pi 0 - 3, so report it at least. AFAIK the first
report about this issue was here [1] and identified the offending
commit:
96cb9d055445 ("hwrng: bcm2835 - use hwrng_msleep() instead of
cpu_relax()")
#regzbot introduced: 96cb9d055445
I was able to reproduce this issue with a Raspberry Pi 3 B+ on Linux
6.5-rc6 (arm64/defconfig).
Before:
time sudo dd if=/dev/hwrng of=/dev/urandom count=1 bs=4096 status=none
real 3m29,002s
user 0m0,018s
sys 0m0,054s
That's not surprising. But also, does it matter? That script has
*always* been wrong. Writing to /dev/urandom like that has *never*
ensured that those bytes are taken into account immediately after. It's
just not how that interface works. So any assumptions based on that are
bogus, and that line effectively does nothing.
Fortunately, however, the kernel itself incorporates hwrng output into
the rng pool, so you don't need to think about doing it yourself.
So go ahead and remove that line from your script.
Thanks for your explanation. Unfortunately this isn't my script.
And I assume it's in the standard install of the RpiOS or similarly
widespread?
the repo / script is specific for Raspberry Pi / Debian.
I'm
just a former BCM2835 maintainer and interested that more user stick to
the mainline kernel instead of the vendor ones. I will try to report the
script owner.
thx
I made a pull request [1] in order to avoid longer discussions and today
it has been merged :)
[1] - https://github.com/RPi-Distro/raspberrypi-sys-mods/pull/77
