Re: Dumps on kernel panic
alex@cconcepts.co.uk
Wed, 5 Jul 1995 12:38:59 +0100 (BST)
> writes:
> >On system boot, allocate a fixed number of physical pages for preserving
> >'important' data. Let's say 2Mb (yes, I propose this only as a configuration
> >option!).
>
> The problem with this is how it affects the failure mode. Two megabytes
> less memory on a system will mean it's swapping differently, using less
> buffer cache, etc. If it's a disk driver or perhaps memory management
> problem, it may not fail in the same way once the debugging is turned
> on.
>
> >Here's the not-very cunning bit: Most PC's when you press the reset button
> >do *not* clear memory. If they do, it's often the memory check that
> >does it and BIOS initialisation, which often only affects the bottom
> >megabyte, and even then not always that. If the PC memory checks above
> >1Mb (which is normally determined by some BIOS word being 4321 or 1234
> >or similar - all documented) then it will, admittedly, corrupt this
> >area, but we can prevent this by setting the word appropriately which
> >will fix us up the majority of case.
>
> I've seen a fair number of flakey Linux systems which crap out when
> they reboot, perhaps requiring a power cycle.
>
> >Note you aren't getting memory for free - you are losing 2Mb of RAM. This
> >option tush isn't going to suit everyone, but it might be a useful debugging
> >tool.
>
> It has to suit average users, since they're the people who need it most. If
> I can't reproduce your problem, and can't get a good idea what's happening
> inside your machine, I'm not going to fix your problem.
There's some truth in this. However some would argue normal users shouldn't
be running development kernels, and it was these kernels I was aiming the
patch at. Also consider the other proposal: if you think systems are sometimes
as flaky as you would suggest (and you may well be right), do you
really want them dumping over your HD?
Alex
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