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Date:      Sun, 17 Nov 2019 10:02:11 -0800
From:      Conrad Meyer <cem@freebsd.org>
To:        Kyle Evans <kevans@freebsd.org>
Cc:        Conrad Meyer <cem@freebsd.org>, Mark Murray <markm@freebsd.org>,  Robert Crowston <crowston@protonmail.com>,  "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org>
Subject:   Re: Initial support for bcm2838 RNG
Message-ID:  <CAG6CVpXOXTUrrVaNOi_6QxsdkgvrodeaOkft7Q%2B18sLDhPmS%2Bw@mail.gmail.com>
In-Reply-To: <CACNAnaFxiEP8sZ0HLw1%2BpiRMYqivCyby349FMJjtHTXz3-ve4A@mail.gmail.com>
References:  <w0qoeMk_XAZYjTShtjgVdPgjrbL3HOfYBcoT-XZeGohC-W3S0THV3dFJXrm51PhYxgkth3M75DszWna9o-OXXS6rPjOeCAUJyNVmlbV0kUU=@protonmail.com> <CACNAnaGUwZ9d0_MFOh7SsG7mDqbZTAym=dqXQRW_Y3CH%2Bai%2BdA@mail.gmail.com> <2F178D6A-300B-4683-84D6-CDB6924877E5@FreeBSD.org> <CACNAnaFxiEP8sZ0HLw1%2BpiRMYqivCyby349FMJjtHTXz3-ve4A@mail.gmail.com>

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I don=E2=80=99t think csprng=E2=80=99s blocker level review requirement ext=
ends to
individual drivers, but I might be mistaken. The kind of things we care
about (imo) are, in order: the core randomdev device, the Fortuna
implementation, the generic entropy gathering, and that entropy  data can
only be used once =E2=80=94 don=E2=80=99t expose it to a user and also feed=
 it to
randomdev. Also, arc4random et al.

Personally, I don=E2=80=99t have the expertise with this particular hardwar=
e to
find anything objectionable about this change. The actual change to the
harvest function in this driver is de minimis. As far as I=E2=80=99m concer=
ned, it
looks good to me; ship it!



On Sun, Nov 17, 2019 at 06:29 Kyle Evans <kevans@freebsd.org> wrote:

> On Sun, Nov 17, 2019 at 4:03 AM Mark Murray <markm@freebsd.org> wrote:
> >
> > Hi,
> >
> > > On 16 Nov 2019, at 18:59, Kyle Evans <kevans@FreeBSD.org> wrote:
> > >
> > > On Sat, Nov 16, 2019 at 12:48 PM Robert Crowston via freebsd-arm
> > > <freebsd-arm@freebsd.org> wrote:
> > >>
> > >> I have made a first cut at supporting the Broadcom 2838 hardware
> random number generator, as found on the Raspberry Pi 4.
> > >>
> > >> Diff:
> https://github.com/freebsd/freebsd/compare/master...RobCrowston:pi4-hwrng
> > >>
> > >> This extends the existing bcm2835_rng.c driver to function on the
> Pi4. Unfortunately I do not have a Raspberry Pi 3 board to confirm it sti=
ll
> works there, but on my Pi4, it generates (apparently) random numbers.
> > >>
> > >
> > > Hi,
> > >
> > > No worries- I've got access to a Pi 3 for regression testing. Can you
> > > throw what you've got into Phabricator [0] and add me as a reviewer?
> > > We can iterate/review from there.
> >
> > Please also add markm@ and cem@ (or csprng@). You'll need one of us to
> OK the commit.
> >
>
> Hi, (adding cem@ to CC list)
>
> Is there a document or something outlining what csprng@ wants to
> accomplish? I definitely don't object to adding you guys on this one
> (both because of the csprng@ origin story and this touches just enough
> actual RNG code path to warrant it, at a glance), but going forward-
> is csprng@ wanting to audit pre-existing stuff as it gets touched in
> any way (e.g. existing driver, just adding compatibility bits to make
> it probe/attach on new board), or just any new code actually affecting
> RNG?
>
> Thanks,
>
> Kyle Evans
>



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