Hi Mauro, As far as I know MT7628 only has a hw crypto engine.
I have only the same programming guide as yours so I can't tell you what does the "RESV1 Select Random Generator mode" mean. Best Regards, Weijie On Wed, 2020-01-08 at 14:37 +0100, Daniel Schwierzeck wrote: > +cc Weijie > > On 1/7/20 6:43 PM, Mauro Condarelli wrote: > > Thanks Daniel. > > > > On 1/7/20 4:58 PM, Daniel Schwierzeck wrote: > >> On Tue, Jan 7, 2020 at 3:30 PM Mauro Condarelli <mc5...@mclink.it> wrote: > >> ... > >>> I also have problems with entropy pool in Linux, do you happen to know > >>> if (and how) MT7628 supports HWRNG? > >> what problems exactly? > > Currently it takes a LOT of time to fill-up the entropy pool > > (over half an hour) and on first startup, when it has to > > generate ssh keys and other stuff system is virtually dead > > for that long. > > if possible you should generate the host keys on the first SSH > connection attempt. Otherwise the time of generation is predictable. If > you use dropbear you can configure that. > > >> > >> On a embedded device you usually can only add randomness from > >> interrupts sources to the entropy pool > >> due to lack of disk or input devices. On a router the most interrupts > >> are typically generated by drivers > >> for ethernet and SPI/NAND/MMC controllers. You could use user-space > >> daemons like haveged [1] > >> to add more randomness from hardware events. > > I tried that and it helps. > > I also found *traces* pointing in the direction of hardware > > support for RNG in my SoC; I have ca opy of the (badly > > incomplete) "MT7628 PROGRAMMING GUIDE" and it > > reports in "PWM1 Control register" an "interesting" field: > > RESV1 Select Random Generator mode. > > This males a lot of sense because this SoC is meant to implement > > Wireless routers, so crypto and random acceleration would > > be very useful. > > Unfortunately I don't have more precise information, hence > > the question. > > maybe Weijie from Mediatek can tell if MT7628 has a HWRNG. But PWM1 > sounds more like a pulse width modulator and shouldn't be related to a > HWRNG. >
