[ECOS] Problem linking eCos application

Thomas Koeller thomas@koeller.dyndns.org
Wed May 7 22:18:00 GMT 2003

I have come across a strange problem when building an eCos
application for the ARM AT91 target. I noticed that code placed
in section .text is misaligned. Here is an excerpt from the map
file that illustrates the problem:

.text           0x00008040    0x10eb0
                0x00008040                _stext = <code 335> (.)
                0x00008040                PROVIDE (__stext, <code 335> (.))
 .text          0x00008040      0x4a4 /projects/ecos-devel/tkoeller/mk2/ecos/build/install/kernel-debug/mk2-kernel-ram-install/lib/vectors.o
                0x00008409                hal_interrupt_stack_call_pending_DSRs
                0x00008469                __gccmain
                0x00008175                reset_platform
                0x0000806d                reset_vector
                0x00008475                _sp
                0x0000846d                _psr
                0x0000809d                start

There is this mysterious, odd-sized gap between the start of the
.text section at 0x00008040 and reset_vector at 0x0000806d, and all
labels are placed at odd addresses. In vectors.S I found the

// Startup code which will get the machine into supervisor mode
        .global reset_vector
        .type   reset_vector,function
        PLATFORM_SETUP1         // Early stage platform initialization
                                // which can set DRAM size at 0x40
                                // see <cyg/hal/hal_platform_setup.h>

Since this is the first and only reference to .text in this file,
I would have expected reset_vector to be located at the very
beginning of that section. The problem does only show for debug
builds (-O0 -ggdb3), not for release builds (-O3), where everything
is properly aligned. None of the other sections (and there is a lot
of those, as I am compiling with -ffunction-sections) shows this
kind of misalignment:

There is another, possibly unrelated problem: much later in the map
file the following lines appear:

 .text          0x0001476c       0x81 /projects/ecos-devel/tkoeller/mk2/ecos/build/install/kernel-debug/mk2-kernel-ram-install/lib/libtarget.a(hal_arm_arch_context.o)
                0x000147d5                hal_setjmp
                0x000147b5                hal_thread_load_context
                0x00014799                hal_thread_switch_context
                0x000147e1                hal_longjmp
 *fill*         0x000147ed        0x3 00

- odd addressses and a gap at the beginning again -, and finally:

 .text          0x00015398       0xb0 /tools/H-i686-pc-linux-gnu/lib/gcc-lib/arm-ecos-elf/3.2.2/libgcc.a(_divsi3.o)
                0x00015398                __divsi3
 .text          0x00015448       0xd4 /tools/H-i686-pc-linux-gnu/lib/gcc-lib/arm-ecos-elf/3.2.2/libgcc.a(_modsi3.o)
                0x00015448                __modsi3
 .text          0x0001551c        0x4 /tools/H-i686-pc-linux-gnu/lib/gcc-lib/arm-ecos-elf/3.2.2/libgcc.a(_dvmd_tls.o)
                0x0001551c                __div0
 .text          0x00015520       0x50 /tools/H-i686-pc-linux-gnu/lib/gcc-lib/arm-ecos-elf/3.2.2/libgcc.a(_ashrdi3.o)
                0x00015520                __ashrdi3
 .text          0x00015570      0x654 /tools/H-i686-pc-linux-gnu/lib/gcc-lib/arm-ecos-elf/3.2.2/libgcc.a(_udivdi3.o)
                0x00015570                __udivdi3
 .text          0x00015bc4      0x65c /tools/H-i686-pc-linux-gnu/lib/gcc-lib/arm-ecos-elf/3.2.2/libgcc.a(_umoddi3.o)
                0x00015bc4                __umoddi3
 .text          0x00016220       0x98 /tools/H-i686-pc-linux-gnu/lib/gcc-lib/arm-ecos-elf/3.2.2/libgcc.a(_udivsi3.o)
                0x00016220                __udivsi3
 .text          0x000162b8       0xc0 /tools/H-i686-pc-linux-gnu/lib/gcc-lib/arm-ecos-elf/3.2.2/libgcc.a(_umodsi3.o)
                0x000162b8                __umodsi3

Shouldn't all references to one particular section be concatenated?
Is this a side effect of -ffunction-sections? I am using gcc-3.2.2
and binutils, all built from sources (on Linux).

I'd appreciate very much any help anybody can give!



Thomas Koeller, Software Development

Basler Vision Technologies
An der Strusbek 60-62
22926 Ahrensburg

Phone	+49 (4102) 463-390
Fax	+49 (4102) 463-46390


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