Date: Sat, 3 Feb 2001 16:38:28 -0800 From: Kris Kennaway <kris@obsecurity.org> To: Christopher Farley <chris@northernbrewer.com> Cc: Vlad <tmd@tmd.df.ru>, freebsd-questions@FreeBSD.ORG Subject: Re: PANIC?! what is that? Message-ID: <20010203163828.A41814@xor.obsecurity.org> In-Reply-To: <20010203152523.A24617@northernbrewer.com>; from chris@northernbrewer.com on Sat, Feb 03, 2001 at 03:25:24PM -0600 References: <20010203160903.A711@tmd.df.ru> <20010203152523.A24617@northernbrewer.com>
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--Kj7319i9nmIyA2yE Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Sat, Feb 03, 2001 at 03:25:24PM -0600, Christopher Farley wrote: > I'm not sure if this is the 'best' definition, but a panic is an > unrecoverable error which occurs in the kernel. Since the system > can't recover, it 'panics' and shuts down as gracefully as possible. That's a pretty good description. > Speaking as someone who has never seen a FreeBSD kernel panic, I > would consider it a *bad thing*, probably the result of a misconfigured > custom kernel or a hardware problem. A third possibility is a bug in FreeBSD. For panics which you can easily reproduce by doing a specific set of actions, chances are it could be a bug. For "random" panics, or panics which start occurring in situations when they never did before, hardware is usually the best place to start looking. Panics under high server load often indicate a misconfigured kernel, which has some hard-coded resource limit set too low (i.e. the system is running out of resources and has no option but to reboot to recover) > Is it possible to write C code (delibarately or otherwise) that > would cause a kernel panic? Yep. In fact the main trick when writing kernel code is to make it NOT cause a kernel panic - if you can solve that, you're halfway there :-) Code run in userland by an unprivileged user shouldn't be able to panic a properly configured kernel, though. Kris --Kj7319i9nmIyA2yE Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.4 (FreeBSD) Comment: For info see http://www.gnupg.org iD8DBQE6fKSEWry0BWjoQKURAmcGAJ4yLTIxAus5q4rap35tMqhZQ8X6IgCdGHQf iwm+Zu4pQFVD6KHxjLPAfkM= =/yud -----END PGP SIGNATURE----- --Kj7319i9nmIyA2yE-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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