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Re: trap handler for unaligned memory read/write

To: Ralf Baechle <ralf@oss.sgi.com>
Subject: Re: trap handler for unaligned memory read/write
From: Jun Sun <jsun@mvista.com>
Date: Fri, 15 Sep 2000 17:02:50 -0700
Cc: linux-mips@oss.sgi.com, linux-mips@fnet.fr
References: <39C29018.9389FBCE@mvista.com> <20000916012853.A16047@bacchus.dhis.org>
Sender: owner-linux-mips@oss.sgi.com
Ralf Baechle wrote:
> > For short-term solutions, we can have trap handler that supports the
> > unaligned read/write.  Does anybody know if there is such a trap handler
> > for MIPS?
> 
> It's right there in your kernel ...
> 

Cool! I found it.

> You _really_ _really_ want to avoid relying on the unaligned trap handler.
> Performancewise that's equivalent to a swapping on a floppy disk on the
> Mars over NFS via avian carriers ...
> 
> However unaligned accesses will result in an address error exception not
> bus error therefore I suspect you've got another problem.
>

I got the error when I use gdb to debug kernel.  I suppose the gdb stub
intercepted the error and report it as BUS error.  We should make
gdb-stub a little smarter  ...

Jun

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