pc386dx exception 6 was Re: 4.6.0pre2 and docs released

Angelo Fraietta angelo_f at bigpond.com
Fri Apr 25 01:59:19 UTC 2003

Angelo Fraietta wrote:

> Joel Sherrill wrote:
>>Angelo Fraietta wrote:
>>>Joel Sherrill wrote:
>>>>I am in agreement with Ralf's hunch here.  including iostream is bound
>>>>to be
>>>>putting some ctor in the system.  It has to be doing something that is
>>>>legal on a vanilla i386 system.  It could be because of inline assembly
>>>>is not i386 pure or incorrect code generation for pure i386 that no one
>>>>has noticed because most people are Pentium and above for Linux, BSD,
>>>>We really need to know that address of the illegal instruction so we can
>>>>figure out where it is coming from.  Fixing it then will probably be
>>>So how do I find the address?
>>If you don't have visibility with a debugger, then all I know to do is 
>>modify the default exception handler to print the eip somewhere you 
>>can see it.
>>When I look at _defaultExcHandler in cpukit/score/cpu/i386/cpu.c, 
>>it already is printing eip.  Are you sure it isn't there?  If it 
>>has scrolled off, move the print with the eip to the end so it 
>>is visible or switch the console to a com port so you have scroll
>PC 104125
>The instructions there are
>104125:	f0 0f c1 05 5c 0d 15 	lock xadd %eax,0x150d5c
In have done an objdump on my working exe and lock xadd is in quite a few places.

If I do an objdump on my exe built with gcc295, lock xadd is nowhere at all.

I did a search on google for lock xadd and in quite a few places it says it is an illegal instruction. It is probably a GCC issue

Angelo Fraietta

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