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Date: Mon, 18 Mar 1996 17:44:15 +1100
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199603180644.RAA10248@godzilla.zeta.org.au>
To: current@freebsd.org, mark@grondar.za
Subject: Re: /dev/random - an idea/proposal
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>I am not completely happy with my current method of selecting the
>interrupts for /dev/random right now. (There is rndcontrol(8) with
>some command-line switches, and sysconfig has a line to edit). It
>is too easy to overlook, and I am very keen that /dev/random be seen
>to provide a decent source of entropy.

Neither am I, for the opposite reasons :-).  The default sysconfig
setting of rand_irqs is almost useless except to print an annoying
message to announce rndcontrol (add_keyboard_randomness() calls
add_timer_randomness() a nearly constant number of usec before
add_interrupt_randomness() for the keyboard interrupt calls
add_timer_randomness()).

>I would like some way to be able to choose these at kernel build
>time - ie at the time the system manager configures her kernel,
>she nominates that a particular device's interrupts should be used.

>This I would like to do by adding a keyword "random", syntactically
>similar to "conflicts" to the config(8) grammar. This will then set

This would be far too much trouble.  As well as hacking config, you
would have to:
- fix the problems that stop "conflicts" from working for PCI and
  EISA devices
- update userconfig and dset to support the new flag

A kernel option to set a bitmap of the interrupts used to generate
randomness would be easier to implement, but it would be easier to
overlook than rndcontrol(8).

Bruce