Date: Wed, 22 Sep 2010 17:43:14 +0300 From: Andriy Gapon <avg@freebsd.org> To: Gavin Atkinson <gavin@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r212964 - head/sys/kern Message-ID: <4C9A1602.4020204@freebsd.org> In-Reply-To: <1285163200.64197.10.camel@buffy.york.ac.uk> References: <201009211507.o8LF7iVv097676@svn.freebsd.org> <1285163200.64197.10.camel@buffy.york.ac.uk>
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on 22/09/2010 16:46 Gavin Atkinson said the following: > Ignoring the rest of the discussion about locking, I think this is a > step in the right direction. However, what I feel we should be strongly > considering is for textdumps to be enabled by default on release media. > > As more groups choose to use the kernels from the release media (PC-BSD, > FreeNAS, etc) and put them into places where end users are never > expected to recompile kernels, having textdumps enabled by default in > RELEASE kernels becomes a bigger and bigger priority. Groups like > PC-BSD don't necessarily have the time or skills to do the needed kernel > debugging (and nor should they have to, it's not their purpose), so > anything we can do in releases to make sure we have enough info to > resolve panics seen by their users is a big bonus. > > Is there any real reason why we shouldn't go down this route? textdumps need DDB. textdumps also need dumpdev which is not enabled by default in /etc/defaults/rc.conf, but that's easier to fix for any individual user or a FreeBSD "distribution". I originally suggested to include DDB in the stable GENERICs. But that has a number of consequences: 1. With DDB a panic results in a system going to ddb prompt instead of rebooting, unless KDB_UNATTENDED is also specified. System not rebooting on panic may be a POLA violation and an inconvenience. However, a user can change this using debug.debugger_on_panic=0 sysctl. Although, sysctl time might be too late in some cases, not sure. 2. Adding KDB_UNATTENDED to GENERIC may have unexpected effect for users that include GENERIC in their kernel config and then extend/trim it with local directives. So another possible POLA violation. Again, fixable by debug.debugger_on_panic=1 with all the howevers and althoughs. For me personally, the significant benefits outweigh possible minor/temporary inconveniences and surprises, but this opinion is not shared by all developers. Really besides the point, but such FreeBSD "distributions" like FreeNAS and PC-BSD can really use their own kernel config, they don't have to use the same GENERICs. P.S. I think that it would have been better if you followed up to my proposal on arch@. -- Andriy Gapon
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