Hello Tom,



some days ago I discovered a GCC bug on interrupt service routines for functions
with

__attribute__((interrupt("IRQ"))). At GCC-Bugzilla I found that this
bug has still been reported in

2005 under bug report #16634 in which you are involved in. Do you know why this
bug is still

"UNCONFIRMED"?!?



The bug still persists in:

arm-elf-gcc (GCC) 4.0.1

arm-elf-gcc (GCC) 4.1.0



Do you (or somebody else) have a gcc-patch to solve this problem? I took a look
to the gcc sources

by myself but the problem occurs in conjunction with optimization under
conditions, where LR

register is used for subroutine branches, and this could a little bit more
tricky to solve it than

just hacking the ARM section of GCC!



Can somebody confirm this bug in the binary-tool-chain from www.gnuarm.com or on
other GCC-based

cross compiler versions? It seems gnuarm don't have any special patches
against this problem, too.

(See test-case below!)



At the moment I'm using a dirty workaround by generating correct entry and
exit code "manually" in a

naked function.



Thanks,

     Sten



-----------------

Test-case:



#include <stdio.h>

#include <stdlib.h>



void irqFunc2a(void) __attribute__((interrupt("IRQ")));

void dummy(void);



void irqFunc2a(void) {

        dummy();

}

void dummy(void) {

        int test;



        test = *((volatile char*) 0xffff);

        test += 10;

        *((volatile char*) 0xffff) = test;

}



Compile these functions with:

$ arm-elf-gcc -mcpu=arm7tdmi-s -mthumb-interwork -fomit-frame-pointer -c
test.c

OR

$ arm-elf-gcc -mcpu=arm7tdmi-s -mthumb-interwork -O2 -c test.c



and have a look at operations on LR register at entry and exit code of
irqFunc2a() with:

$ arm-elf-objdump -DS test.o



-- 

/************************************************

 Do you need a tiny and efficient real time

 operating system (RTOS) with a preemtive

 multitasking for LPC2000 or AT91SAM7?



   http://nanortos.net-attack.de/



 Or some open-source tools and code for LPC2000?



   http://www.net-attack.de/



************************************************/

Sten wrote:



>Hello Tom,

>

>some days ago I discovered a GCC bug on interrupt service routines for
functions with

>__attribute__((interrupt("IRQ"))). At GCC-Bugzilla I found that
this bug has still been reported in

>2005 under bug report #16634 in which you are involved in. Do you know why
this bug is still

>"UNCONFIRMED"?!?

>

>The bug still persists in:

>arm-elf-gcc (GCC) 4.0.1

>arm-elf-gcc (GCC) 4.1.0

>

>Do you (or somebody else) have a gcc-patch to solve this problem? I took a
look to the gcc sources

>by myself but the problem occurs in conjunction with optimization under
conditions, where LR

>register is used for subroutine branches, and this could a little bit more
tricky to solve it than

>just hacking the ARM section of GCC!

>

>Can somebody confirm this bug in the binary-tool-chain from www.gnuarm.com
or on other GCC-based

>cross compiler versions? It seems gnuarm don't have any special patches
against this problem, too.

>(See test-case below!)

>  

>

I am not sure what your question is. Why do you feel you have to 

intentionally suppress the apcs stack frame?

	Regards,



TomW



-- 

Tom Walsh - WN3L - Embedded Systems Consultant

http://openhardware.net, http://cyberiansoftware.com

"Windows? No thanks, I have work to do..."

----------------