SUMMARY: more on panic swtch - kadb and savecore

From: Stephen Harris (
Date: Mon Sep 04 1995 - 10:56:35 CDT

In a recent message, Vahsen Rob said:
> From: (Vahsen Rob)

> Would you be so kind to share your gathered knowledge to the Sun Managers
> List. The thing about kadb and savecore sounds intresting.....

It's actually quite simple, but since others seem to be as in the dark
as I was, this might help...

1) kadb.
   Instead of booting normally, boot kadb (ie from the prom "b kadb").
   This will load and run /vmunix, but when the kernel crashes, instead of
   rebooting the system it will drop into an 'adb-like' debugger and let
   you perform stack traces etc on the recently crashed kernel.

2) savecore
   When the machine panics and dumps it writes the current in-core memory
   image to the swap partition. Early in the boot sequence before swapping
   is enabled you can use the savecore command which will extract the dumped
   image from swap and save it in the filesystem, enabling you to perform
   post-mortem debugging on the kernel.

Both methods allow you to post-mortem debug the kernel. Helpful if you have
deep(ish) knowledge of kernel structures/memory, or if someone is trying to
help you via email and you can send them stack traces etc.

Stephen Harris -
MatriX Publishing Network

This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:10:32 CDT