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To: Warner Losh <imp@bsdimp.com>
Subject: Re: svn commit: r274739 - head/sys/mips/conf
In-reply-to: <4C2BD093-BEA2-47F9-B575-90342712E9B2@bsdimp.com>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
References: <201411200552.sAK5qnXP063073@svn.freebsd.org>
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Date: Tue, 25 Nov 2014 06:40:47 +0000
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Cc: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no>,
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--------
In message <4C2BD093-BEA2-47F9-B575-90342712E9B2@bsdimp.com>, Warner Losh =
writes:

>What's the minimum specs required for get_cyclecount()?

In randomness context:  That there exists a complex and unpredictable
cache-hierarchy which makes the exact number of cycles for any one
instruction pseudo-random.

Apart from x86 and zSeries no currently relevant architecture has that.

-- =

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    =

Never attribute to malice what can adequately be explained by incompetence=
.