Using newlib (was: [Efi332] Building newlib/libgloss for MPC555)

[bowtievette at aol.com]

-----Original Message-----
From: Gunter Magin <gm at ib-magin.de>
To: efi332 at diy-efi.org
Sent: Tue, 9 Aug 2005 15:35:32 +0200
Subject: Re: Using newlib (was: [Efi332] Building newlib/libgloss for MPC555)


Hi,

> It's hard to tell what happened when I run the code because I don't trust
> this debugger. I did set a software breakpoint at mbx-outbyte, it never got
> there. The debugger says the machine is still running (not in BDM debug
> mode), but nothing is happening. So I click on "halt" and check the PC reg
> and find I'm at 0x1000 with an illegal opcode. The exception vectors go
> 0x100 through 0xE00, I don't find one for 0x1000 so I'm not sure why it goes
> there.

Table 3-21 on the MPC555UM says 0x1000 is "Implementation dependent SW
emulation", that is, an illegal opcode. Chances are the linker has
picked the wrong library. Double check the map file.
You have to be careful with that exception. It may be only the last exception 
that occurred. Dave, if you have not populated your exception table, or if the
table is stale with respect to your application in RAM (I presume you are 
running from RAM), then almost any exception will find some illegal opcodes
and trigger the software emulation exception (0x1000). To unravel the source, 
you must have your table populated so that you can determine when the various 
exceptions are called. Counters, setting discretes, etc are useful here.
 
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