Date: Mon, 2 Aug 2004 19:54:10 -0700 (PDT) From: Don Lewis <truckman@FreeBSD.org> To: danfe@nsu.ru Cc: jhb@FreeBSD.org Subject: Re: cvs commit: src/sys/alpha/alpha mem.c src/sys/alpha/conf GENERIC src/sys/alpha/include memdev.h src/sys/amd64/amd64 io.c mem.c src/sys/amd64/conf GENERIC NOTES src/sys/amd64/include iodev.h memdev.h src/sys/conf NOTES files files.alpha files.amd64 ... Message-ID: <200408030254.i732sBtS077748@gw.catspoiler.org> In-Reply-To: <20040803021718.GA5460@regency.nsu.ru>
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On 3 Aug, Alexey Dokuchaev wrote: > On Mon, Aug 02, 2004 at 04:00:00PM -0400, John Baldwin wrote: >> Why in the world are /dev/null and /dev/zero optional? /dev/[k]mem >> and /dev/io I can accept for those with uber-high security paranoia, but I >> can't think of any good reason to have a kernel without /dev/null >> and /dev/zero. To me it seems that this creates way more foot shooting >> potential than benefit. It's one thing to have device drivers for hardware >> that may or may not be present optional, but /dev/null and /dev/zero do not >> fall into that case. > > OTOH, if someone wants to build mega-tight kernel image with everything > possible taken out by modules, modularizing /dev/null and /dev/zero > might make some sence. We already have /dev/random as a module anyways. You might have trouble doing anything useful on the system without /dev/null. For instance /bin/sh won't be able to run background jobs, /bin/csh will close stdin of any background jobs (which might cause wierd things to happen), users of daemon(3) won't properly disconnect from the tty which started them, and there are a number of references to /dev/null in the /etc and /etc/rc.d scripts. In the case of i386, the size of the text+data size of null.ko is a little over 2K. From a quick look at the source, it looks like at least half of this is the module support code. BTW, I think daemon(3) and /bin/csh should check the return value when they attempt to open(_PATH_DEVNULL, ...).
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