Re: egcs 971008 on Linux/PPC - test results

[Michael Meissner <meissner at cygnus dot com>]

Richard Henderson writes:
| On Wed, Oct 15, 1997 at 11:55:21PM -0400, Elliot Lee wrote:
| > Is there documentation somewhere that details the different purposes of
| > these crt* files, so I can narrow things down and find which one might be
| > at fault?
| 
| crti/n creates the .init & .fini sections that are invoked by ld.so on
| startup/shutdown.  crtbegin/end interfaces between the section-is-a-
| function mechanism used by crti/n to the table-of-function-pointers
| initialization preferred by g++ for running its constructors.
| 
| So .init invokes __do_global_ctors_aux, which calls the c++ constructors.
| 
| > I tried breaking on _start in gdb and single-stepping into
| > things, but gdb merrily goes on by :(
| 
| Try "b *_start+4".  I've had more luck with the second insn in the past,
| for whatever reasons.
| 
| > 0x182ee70 <__do_global_ctors_aux+72>:   lwz     r29,0(r9)
| > 0x182ee74 <__do_global_ctors_aux+76>:   mtlr    r29
| > 0x182ee78 <__do_global_ctors_aux+80>:   blrl
| 
| This is "r29 = *r9; (*r29)();".  So either the table of constructors is
| garbage, or you managed to get a pointer to something else.  Find out what
| symbol lives near r9.
| 
| Unlike the Alpha, which has constraints the hackery in crtstuff completely
| breaks, I wasn't aware of anything that ppc would care about in there. 
| But obviously something has gone wrong.  What differences do you see with
| objdump -dr between the two versions of crtbegin/end?

Now that I think about it, I think I know what the problem is, and its
been something I meant to fix but it kind of fell off my plate.
Basically the Linux PowerPC stuff creates crt{begin,end}.o from the
System V configs and crt{i,o}.o from the eabi configs.  My hunch is to
do Linux the same way I did eabi, and eliminate crt{begin,end}.

-- 
Michael Meissner, Cygnus Solutions (East Coast)
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