Date: Mon, 26 Jun 2000 20:35:12 -0400 From: "Jeroen C. van Gelderen" <jeroen@vangelderen.org> To: Warner Losh <imp@village.org> Cc: Peter Wemm <peter@netplex.com.au>, Mark Murray <mark@grondar.za>, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/usr.sbin Makefile src/usr.sbin/rndcontrol Makefile random.4 rndcontrol.8 rndcontrol.c Message-ID: <3957F6C0.B8D8E006@vangelderen.org> References: <20000626210416.324691CD7@overcee.netplex.com.au> <200006262227.QAA28257@harmony.village.org>
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Warner Losh wrote:
>
> In message <20000626210416.324691CD7@overcee.netplex.com.au> Peter Wemm writes:
> : Err.. why? We now have a generic place to hook into at the nexus if the
> : driver approves. For shared irqs, we can check that all handlers are OK
> : with it. We have flags available..
>
> Even without flags, we can make a simple kobj_true() and
> kobj_false(). The genertic nexus thing could then ask the drivers
> "Can I use your IRQ for entropty?" with some method
> (device_irq_random, say) and the driver would default to
> using the kobj_true method (return 1;) for this, but those drivers
> that don't think their interrupts will be random enough, can
> implemetne device_irq_random as kobj_false.
Urm, we're talking security here. The default should be false
unless the driver knows it's IRQ makes for a reasonable entropy
source. For shared IRQs you would need to "AND" all the
return values together.
Eventually it may be better to have the device export an
entropy pseudo-device itself. We would need those for pure
entropy gathering devices anyway but even in the case of a
network driver it can be useful: the driver has access to
it's IRQ timings as well as network statistics from which
entropy can be distilled. The network driver could even
disable it's entropy device interface unless the link is
actually up and data is arriving.
My EC$ 0.02,
Jeroen
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