Messages in this thread | | | Date | Mon, 16 Jun 2014 09:31:08 +0200 | From | Torsten Duwe <> | Subject | Re: [Patch v5.1 03/03]: hwrng: khwrngd derating per device |
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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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