From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael Kerrisk (man-pages)" Subject: Re: Unit of /proc/sys/kernel/random/poolsize Date: Sun, 20 Dec 2015 22:02:10 +0100 Message-ID: <56771752.90705@gmail.com> References: <5672699D.5010803@gmail.com> <56732173.20905@bfs.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56732173.20905-fPG8STNUNVg@public.gmane.org> Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: wharms-fPG8STNUNVg@public.gmane.org Cc: mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, Tom Gundersen , linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-man@vger.kernel.org Hello Walter, On 12/17/2015 09:56 PM, walter harms wrote: > > > Am 17.12.2015 08:51, schrieb Michael Kerrisk (man-pages): >> Hello Tom, >> >> On 10/22/2011 02:13 PM, Tom Gundersen wrote: >>> Hi, >>> >>> This might not be so much a bug report, as a request for clarification. >>> >>> In random(4) it is explained that /proc/sys/kernel/random/poolsize >>> contains the value in bits or bytes in >=2.6 and 2.4 respectively. >>> However, the example in the preceding paragraph assumes a 2.4 kernel >>> is being used, and treats the value as if it were in bytes. >>> >>> I ran across this as I maintain the initscripts for Arch Linux, where >>> we have been (mistakenly) following the example even though we use a >>> 3.0 kernel. Maybe it would be worthwhile to change the example into >>> the 2.6 interface, or at least include a word of caution? >>> >>> I realise that using a value which is too large, probably does no harm >>> at all, but not being cryptography expert, I'd rather not take the >>> chance. >> >> Long after the fact... I applied the patch below. >> Okay? >> >> Thanks for the report. >> >> Cheers, >> >> Michael >> >> PS I am going to be in Oslo a couple of times in coming months. >> Perhaps we could meet up for a beer or so. >> >> diff --git a/man4/random.4 b/man4/random.4 >> index 2519981..4a32aac 100644 >> --- a/man4/random.4 >> +++ b/man4/random.4 >> @@ -171,7 +171,7 @@ This reduces the actual amount of noise in the entropy pool >> below the estimate. >> In order to counteract this effect, it helps to carry >> entropy pool information across shut-downs and start-ups. >> -To do this, add the following lines to an appropriate script >> +To do this, add the lines to an appropriate script >> which is run during the Linux system start-up sequence: >> >> .nf >> @@ -186,7 +186,8 @@ which is run during the Linux system start-up sequence: >> fi >> chmod 600 $random_seed >> poolfile=/proc/sys/kernel/random/poolsize >> - [ \-r $poolfile ] && bytes=\`cat $poolfile\` || bytes=512 >> + [ \-r $poolfile ] && bits=\`cat $poolfile\` || bits=4096 > > I believe it was end of the 80's when $( ) was introduced to replace \` > Since this example is for 2.6 maybe it would be useful to use it and > improve readability ? Yes, of course, and especially so since I use the modern syntax in the new piece that I added. Fixed. Thanks for catching the obvious point that I missed! Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html