On 27 Apr 2006, at 19:58, Matthias Drochner wrote:

> Binutils was updated in -current after the 3.x branch.
>
> The problem appears to be that the exception handling
> information located in the ".eh_frame" section, and pointed
> to by "__EH_FRAME_BEGIN__" is damaged.
>
> On my -current system, the assembler input looks so:
>         .weak   pthread_create
>         .section        .eh_frame,"a",@progbits
> $Lframe1:
>         .4byte  $LECIE1-$LSCIE1
> $LSCIE1:
>         .4byte  0x0
>         .byte   0x1
>         .ascii "zPLR\0"

My assembler input looks the same => C++ front end OK?

> and the output:
> zel637: {47} objdump -j .eh_frame -s throw.o
>
> throw.o:     file format elf64-alpha
>
> Contents of section .eh_frame:
>  0000 1c000000 00000000 017a504c 52000178  .........zPLR..x
> [...]

Again, my object agrees => assembler OK?

> The linker makes __EH_FRAME_BEGIN__ point to this:
> zel637: {59} gdb a.out
> [...]
> (gdb) x/3x &__EH_FRAME_BEGIN__
> 0x120060080 <__EH_FRAME_BEGIN__>: 0x0000001c 0x00000000 0x4c507a01
>
> So far so good.
>
> Your binaries are different:
> zel637: {50} gdb t0
> [...]
> (gdb) x/4x &__EH_FRAME_BEGIN__
> 0x12009da84 <__EH_FRAME_BEGIN__>: 0x00000000 0x0000001c 0x00000000 
> 0x4c507a01

So, as noted, here we diverge.  I guess the linker is to blame.

> Note the extra "0" as first entry -- this causes that the
> data are not accepted by __register_frame_info (which is called
> in early startup), and thus no unwind information is available
> later when the exception is thrown.
>
> I can't tell yet whether the assembler or the linker is to blame,
> but you might find out by looking at the intermediate .s and .o
> files as I did.

So I got the -current sources and started to build a new distribution.  
The build failed, but nevertheless I quickly tried to link using the ld 
from -current, but that only resulted in an invalid system call.  I 
guess I'll have to update sources and replace kernel and tools and 
probably everything else if I want this to work.

Thanks a million!  I have learned a lot today!

// Johan