How to restore boot block after machine crashes?

How to restore boot block after machine crashes?

Post by Jin Guojun[IT » Sat, 13 Jul 1996 04:00:00

When I worked with 2.2-960612-SNAP kernel, sometime when the kernel
panic (dump core is made), part of boot block is screwed up.
F1 ... dos
F2 ... BSD
F3 ... BSD

Default: F?

Press F1 can boot to dos. Press F2, nothing happens, and press F3 machine
Would some one please tell me which part of the boot block has been damaged?
Is there any way to fix this damage, beside to reinstall the it again?

Thanks for any information.


|       Lawrence Berkeley Laboratory    | Bitnet:       --                 |


1. restore crashes remote machine

This is an internally-detected error in `psig'.

Signals are sent to a process by setting a bit in the other process's
`pending signals' mask.  The process is awaked, if appropriate, and
when it eventually runs, it notices the pending signal and calls
`issig' and then `psig'.  psig() determines what to do based on the
current `signal action'.  This action is one of:

        SIG_DFL: take the default action (often, core dump/kill process).
        SIG_IGN: ignore.
        SIG_CATCH, SIG_HOLD: (internal to psignal/issig)

Now, issig() and psignal() are supposed to discard signals with no
effect, and say `no pending signal' for signals that are blocked.
Thus, psig() will panic if either:

        u.u_signal[p->p_cursig] == SIG_IGN


        (p->p_sigmask & (1 << p->p_cursig)) != 0

because both of these mean `the signal is not supposed to do anything'
---for SIG_IGN, `not ever' and for p_sigmask, `not yet'.

There must therefore be a bug in either psignal or issig, or both.
Presumably you are paying Sun for support.  Well, here they go....
In-Real-Life: Chris Torek, Lawrence Berkeley Lab CSE/EE (+1 415 486 5427)

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