On Mon 8 Jun 2009 07:46, Mike Frysinger pondered:
> On Mon, Jun 8, 2009 at 07:46, Robin Getz wrote:
> > On Sun 7 Jun 2009 20:13, Mike Frysinger pondered:
> >> On Sun, Jun 7, 2009 at 18:52, Robin Getz wrote:
> >> > On Sun 7 Jun 2009 18:20, Mike Frysinger pondered:
> >> >> On Sun, Jun 7, 2009 at 18:15, Robin Getz wrote:
> >> >> > On Sun 7 Jun 2009 17:24, [email protected] pondered:
> >> >> >>       Revision
> >> >> >>       6605
> >> >> > <http://blackfin.uclinux.org/gf/project/linux-kernel/scmsvn/?action=browse&path=/&view=rev&root=linux-kernel&revision=6605>
> >> >> >>       Author
> >> >> >>       vapier <http://blackfin.uclinux.org/gf/user/vapier/>
> >> >> >>       Date
> >> >> >>       2009-06-07 16:24:10 -0500 (Sun, 07 Jun 2009)
> >> >> >
> >> >> >>  #ifdef CONFIG_BUG
> >> >> >> +
> >> >> >> +#define BFIN_BUG_OPCODE      0xefcd
> >> >> >
> >> >> > So - I think hooking GENERIC_BUG up is good -- but before we 
> >> >> > willy-nilly start
> >> >> > defining new opcodes - there needs to be a little more discussion 
> >> >> > about
> >> >> > exactly what it should be - and this discussion needs to include more 
> >> >> > than
> >> >> > just us...
> >> >> >
> >> >> > I'm also assuming that we might want to add support for this in the 
> >> >> > assembler?
> >> >> > (eventually? or never?)
> >> >>
> >> >> there is no reason for the opcode to be seen outside of the kernel.
> >> >> the assembler shouldnt disassemble it.
> >> >
> >> > What happens when someone looks at it with objdump? or gdb (JTAG) or 
> >> > kgdb sees it?
> >> >
> >> > I think "kernel bug/warn" or something is better than "invalid 
> >> > instruction"
> >> > (which is what would happen today)...
> >>
> >> i think having it read ILLEGAL is fine.  it's how every other arch
> >> works, and the instruction only gets executed when there is a problem
> >> -- BUG/WARN should not be triggered in the normal case.
> >
> > I thought they way it was written - it will be added inline to every
> > function - won't it?
> 
> yes, but the illegal instruction doesnt actually get executed unless
> there is a problem

Right - but anyone looking at the function where a BUG/WARN can occur will see 
ILLEGAL in the disassembly.

I'm just concerned that it might generate a unnecessary question or two... 
I guess I'm OK with it as is - until those questions come up, and then I'll
add something to the disassembler (which should be the only place necessary
to have something).


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