On Sun, Jun 15, 2014 at 01:11:46AM -0400, Theodore Ts'o wrote:
> OK, I've merged these changes into the random.git tree.
>
> I had to make a few minor changes.
>
> 1) Changes so it would compile on 3.15. (random_write_wakeup_thresh
> got renamed to random_write_wakeup_bits). I'm guessing the patch was
> massaged so that it would apply, but it was never compile tested.
I'm keeping and updating 2 versions, one -current (more or less)
and one for 3.12. I probably missed that when making the discussion changes
back and forth, sorry.
> 2) Fixed a bug in patch #2 so that it would work correctly if the rng
> driver doesn't have an init function (which happens to be the case for
> the tpm-rng driver, which I used for my testing).
The whole thing stems from entropy-challenged s390. 3.12 on s390 compiles
and runs fine. Yields a solid 200 kB/s
TPM RNG is a crook ;-)
> There are also a few minor rough edges that I've noted, but not yet
> fixed. The main one is that if you've compiled the hw_random's
> rng_core into the kernel, changes to
> /sys/modules/rng_core/parameters/* won't actually cause the hwrngd
> kerenl thread to get started. You have to set the parameters before
> you load the rng module in order for them to be activated. And if
> you've compiled the rng module into the kernel, that trick won't work.
With patch 03/03, it is up to the driver author to specify an entropy
quality, which can be overridden at boot time, or when loading
the module, respectively. This should be a constant hardware property.
It would be nice to change it at runtime; but frankly I hope that this
won't be neccessary.
> Fixing this probably means that we need to set up a formal sysfs tree
> under /sys/kernel/hw_random.
Maybe along with more sophisticated steering of how many bits to pick
from which source, if multiple are available.
Thanks,
Torsten
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