From owner-freebsd-stable@FreeBSD.ORG  Sat Jun 25 14:49:41 2011
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Date: Sat, 25 Jun 2011 17:49:38 +0300
From: Andriy Gapon <avg@FreeBSD.org>
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Subject: kern.sync_on_panic
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Does anybody actually use kern.sync_on_panic tunable/sysctl?
If yes, then in what circumstances do you need it?
That is, why any other alternative doesn't work for you?
Like:
1. remounting filesystems R/O before panic if you knowingly provoke it for testing
2. using netboot for your test system
3. using su+j, gjournal or a different filesystem altogether
4. using fsck after reboot

It seems to me that syncing filesystems in panic context is an adventure.  And it
may become even more of an adventure if we introduce code that completely stops
scheduler in and after panic.

-- 
Andriy Gapon