Question on odd Sun behaviour

Joseph Moran mojo at sun.uucp
Mon Sep 2 10:26:24 AEST 1985


In article <415 at dcl-cs.UUCP> de at dcl-cs.UUCP (David England) writes:
>A couple of times now our Sun 120 has done a reboot after this, apparently
>harmless, command line (it didn't use to do this);
>% cat file | csvax lpr
>
>where csvax is a remote machine entry in /usr/host.
>
>The machine goes into KERNEL mode, does a traceback, gives a panic: Address
>error, then reboots. 
>
Well, as it turns out when the Sun kernel copies data out to the user
address space, it doesn't always check data alignment.  If a fault
occurs during the move, the kernel is supposed to detect that this
fault was not really a kernel fault, rather it is to be treated as a
user fault and the system call should return EFAULT or something like
that.  In the 1.x kernels, the address error fault code was not doing
this, and thus a bad pointer to certain system calls could cause an
address error panic.  The address error kernel bug is fixed in Sun
release 2.0.

Thus I'm hoping that you are running a 1.x kernel.  As to what system
call had a misaligned pointer in your example you got me.  I'd look at
a crash dump to look what's happening there.  If you get a 2.0 system
and you have the same system call parameters, the system call will
just fail instead of panic'ing the kernel.

	Joe Moran



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