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Date:      Wed, 12 Sep 2012 11:13:49 -0500
From:      Warner Losh <imp@bsdimp.com>
To:        Ian Lepore <freebsd@damnhippie.dyndns.org>
Cc:        Arthur Mesh <arthurmesh@gmail.com>, Doug Barton <dougb@freebsd.org>, freebsd-rc@freebsd.org, obrien@freebsd.org, RW <rwmaillists@googlemail.com>, d@delphij.net, =?utf-8?Q?Dag-Erling_=EF=BF=BD?= <des@des.no>
Subject:   Re: svn commit: r239569 - head/etc/rc.d
Message-ID:  <317B4762-3530-49E5-B861-67773819FC5E@bsdimp.com>
In-Reply-To: <1347461022.1110.29.camel@revolution.hippie.lan>
References:  <86sjao7q8c.fsf@ds4.des.no> <20120911205302.27484fd6@gumby.homeunix.com> <20120911200925.GA88456@dragon.NUXI.org> <504FA76A.5000209@delphij.net> <20120911211730.GB89188@dragon.NUXI.org> <504FAB87.3020701@delphij.net> <20120911215212.GA89515@dragon.NUXI.org> <504FBD15.8040907@delphij.net> <20120911230121.GA90289@dragon.NUXI.org> <504FC7B0.2060706@delphij.net> <20120912000738.GA90897@dragon.NUXI.org> <1347461022.1110.29.camel@revolution.hippie.lan>

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On Sep 12, 2012, at 9:43 AM, Ian Lepore wrote:

> On Tue, 2012-09-11 at 17:07 -0700, David O'Brien wrote:
>> On Tue, Sep 11, 2012 at 04:22:24PM -0700, Xin Li wrote:
>>> Please consider using sha512...
>>=20
>> What is the performance (boot time) impact on low-end MIPS and ARM
>> systems?
>>=20
>> I'm all for sha512, but don't want to be shot with a machine gun (vs.
>> simple pistol).
>>=20
>=20
> For the embedded systems I take care of, the performance problem on
> low-end systems is likely to be solved by ignoring all of this angels
> dancing on a pin stuff and supplying an alternate kickstart mechanism
> appropriate to the way the system is used (which almost surely won't =
be
> in any national security datacenter).
>=20
> I can assure you that neither shaXXX nor gzip nor anything else that
> eats that many cycles will be involved. :)
>=20
> I just hope one of things coming out of all this is a reasonable
> mechanism for supplying alternate kickstart data.

Yea, it doesn't have to be completely unique per boot, it just needs to =
be something not the same and not too predictable for yarrow to work =
well.  Another part of the entropy will be the timings of all the =
interrupts and what not after things are seeded, and that is very hard =
to control...

Just having it as a decent function that can easily be overridden in =
/etc/rc.conf or some other well-known mechanism would easily solve this =
problem for special needs folks without placing an undue burden on them =
or on the main system.

Warner=



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