svn commit: r212964 - head/sys/kern

[Pawel Jakub Dawidek]

On Tue, Sep 28, 2010 at 03:04:11PM -0400, John Baldwin wrote:
> > I am bigger fan of textdumps than minidumps, because in my opinion
> > textdumps provide quite a lot of useful info. I'm working with FreeBSD
> > kernel for years now and almost entirely avoided gdb for kernel
> > debugging. DDB and printf(9) are in 99% enough for me (maybe I'm too
> > traditional, but that's the fact). I'm not saying that textdumps are
> > enough in 99%, though.
> 
> Have you looked at a /var/crash/core.txt.X file yet?  If not, you should, as
> it is very similar to a text dump.  In fact, it will contain the contents of
> any ddb trace buffer in addition to a stack trace from kgdb, process listing
> from ps, etc.
[...]
> > Another important thing in my opinion is privacy of user's data. Once
> > the data hit the disk it can stay there forever. This is why I use
> > encrypted swap everywhere. I'd never send kernel minidump from my
> > laptop or from any of my servers to anyone, but I'd be happy to send
> > textdump.
> > 
> > I find textdumps a great solution that's in the middle between
> > protecting user's privacy and providing a lot of useful info and I'd
> > much prefer to turn on textdumps by default and eventually extend what
> > we dump, than to make minidumps the default.
> 
> I'm suggesting they provide us the core.txt.X file, not the full minidump.
> A developer could then ask them to run specific commands from a subsequent
> kgdb session to obtain more details.

But you still will have your kernel memory dumped to disk. This is
probably not a problem for most of the users, though.

> > You can always ask user to add this one-line to rc.conf to turn
> > minidump on and provide you the info that was missing in textdump.
> 
> This only works for easily reproducible bugs, and in that case they can turn
> on dumps later without a need for it to be automatic at all.

And I'm arguing that those are very rare situations where there is a
bug, which is hard to reproduce and where textdump won't be of any help.

I'm aware that those are not strong arguments, but just worth taking
into account, IMHO.

-- 
Pawel Jakub Dawidek                       http://www.wheelsystems.com
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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