What the heck is a bus error?

ME dugan at passwall.com
Sat Mar 23 01:52:04 PST 2002


If your booting workstations are running out of memory (you mentioned 32Mb
on client workstations before with no swap yet), you can get errors like
this too. Though, if you get bus errors as a result of being out of
memory at startup, you may want to look to trim down things at startup for
the netbooting clients.

As for compiling kernels for optimized for older CPU, and using them on
newer ones (say optimize (?) for 386 or 486 and use on Pentium, Optimize
for Pentium and use on PPro or Pentium III, or Pentium MMX and use on
Pentium III, I have not seen problems with this yet. (I have seen problems
with optimizing for more advanced CPU and running on older CPU chips.)

What things are still being init-ed?
Client machine can probably drop much of their logging, as well as most
(if not all) of their console based terminals (more memory savings) if
they dont need any inetd services, why start inetd? (You may have these
all removed.)

Many (possibly most) /sbin tools are compiled as static system bins, and
are less efficient with memory when compared with shared objects/memory
savings than apps that can load shared libs and be more efficient with
memory usage. Perhaps the startup scripts are calling several startup
items that are big memory users.... (?)

Do something with virtual memory (if you have not done this yet) and see
if these errors go away....

-ME

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On Fri, 22 Mar 2002, Lincoln Peters wrote:
> The client (code-named "Firewalker"), Isildur, and the server (Palantir) are 
> all running kernel 2.4.9 with any necessary customizations (on Isildur, the 
> stock RH kernel; on Palantir, the NFS server is compiled straight into the 
> kernel; on Firewalker, built-in 3Com ethernet driver, DHCP support, and NFS 
> client).  The only exception is that Firewalker's kernel modules under 
> /lib/modules/2.4.9-31 does not excatly match the kernel it's running, but I 
> should still be able to get Firewalker in a usable enough state to update 
> the modules.
> 
> Could it have to do with CPU optimizations?  The Firewalker kernel is 
> compiled for a Pentium/MMX system, but it's running on a Pentium III.  But 
> shouldn't that still work?  Should I re-compile it for a Pentium III?  (I 
> was hoping to use this netbooting system on some Pentium II machines running 
> Windows 98, but I can worry about them later.)
> 
> 
> >From: "Jeffrey Miller" <jmiller at batnet.com>
> >Reply-To: <talk at nblug.org>
> >To: <talk at nblug.org>
> >Subject: Re: What the heck is a bus error?
> >Date: Fri, 22 Mar 2002 18:18:27 -0800
> >
> >It means that you're trying to dereference a pointer that's not a multiple
> >of the CPU word size.
> >
> >It typically occurs for the same reason as a "segmentation fault" -- a
> >corrupted pointer
> >to a variable, or a link error -- an incompatible library or object file
> >version.
> >
> >Same kernel version and library versions for Isildur and the netbooting
> >stations?
> >
> >Matching kernel version and library versions between the netbooting 
> >stations
> >and the server they're mounting drives off of?
> >
> >Jeff Miller
> >
> >----- Original Message -----
> >From: "Lincoln Peters" <lincoln_peters at hotmail.com>
> >To: <talk at nblug.org>
> >Sent: Friday, March 22, 2002 5:35 PM
> >Subject: What the heck is a bus error?
> >
> >
> > > Well, I started up one of the netbooting workstations, and everything
> >worked
> > > fine until it ran the initscripts.  I kept getting messages from various
> > > programs (e.g. mount) that would die with a "Bus error".  I have no idea
> > > what that means, and as a result, I have no idea how to correct it?
> > >
> > > Can anyone tell me what "Bus error" means, and/or what could be causing
> > > these errors?  The entire client system was copied off of Isildur (my 
> >best
> > > standalone workstation), and except for /etc/fstab and /etc/raidtab, it 
> >is
> > > identical to the setup on Isildur, which works perfectly.
> > >
> > > _________________________________________________________________
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> > >
> >
> 
> 
> 
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