Date: Wed, 19 Nov 2008 23:48:36 -0800 (PST) From: Nate Eldredge <neldredge@math.ucsd.edu> To: Jeremy Chadwick <koitsu@freebsd.org> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: [Testers wanted] /dev/console cleanups Message-ID: <Pine.GSO.4.64.0811192341470.1597@zeno.ucsd.edu> In-Reply-To: <20081120070820.GA19307@icarus.home.lan> References: <e71790db0810271936r1ce4619an1d64c6aae62c3ec1@mail.gmail.com> <20081028081154.GQ6808@hoeg.nl> <20081118213410.GA81783@hoeg.nl> <20081118214919.GM83287@bunrab.catwhisker.org> <7d6fde3d0811190202p4f6d8941h3932b70b8fe1a93a@mail.gmail.com> <20081119104731.GA83366@icarus.home.lan> <20081120063936.GU51761@server.vk2pj.dyndns.org> <20081120070820.GA19307@icarus.home.lan>
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On Wed, 19 Nov 2008, Jeremy Chadwick wrote: > On Thu, Nov 20, 2008 at 05:39:36PM +1100, Peter Jeremy wrote: >> I hope that never gets committed - it will make debugging kernel >> problems much harder. There is already a kern.msgbuf_clear sysctl and >> maybe people who are concerned about msgbuf leakage need to learn to >> use it. > > And this sysctl is only usable *after* the kernel loads, which means > you lose all of the messages shown from the time the kernel loads to > the time the sysctl is set (e.g. hardware detected/configured). This is > even less acceptable, IMHO. But surely you can arrange that the contents are written out to /var/log/messages first? E.g. a sequence like - mount /var - write buffer contents via syslogd - clear buffer via sysctl - allow user logins This way the buffer is cleared before any unprivileged users get to do anything. No kernel changes needed, just a little tweaking of the init scripts at most. If you should have a crash and suspect there is useful data in the buffer, you can boot to single-user mode (avoiding the clear) and retrieve it manually. Seems like this should make everyone happy. -- Nate Eldredge neldredge@math.ucsd.edu
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