Hello Alexander,
Alexander Holler wrote:
to give the topic a better meaning and to summarize what I think is currently happening along with some "pictures" for a better understanding:
We are starting with code (c) and data (d) somewhere in the memory:
|cd |
The relocation in start.S should achieve this:
| cd|
Yep, and this works fine on boards, I have access( arm1136 qong, arm926ejs tx25, suen3 arm926ejs kirkwood, mx25 magnesium, armv7 omap3_beagle)
That means code and data should be moved upwards. What currently is happening is the following:
| d c |
really?
I posted you on 27.10.2010 in u-boot%irc.freenode.org (couldn;t find this in the history :-( ) a log on the tx25, where this works fine, and we came to the opinion, that you maybe have problems with your toolchain! IIRC you use gcc-4.5x ... Alexander, did you tried (as you thought to do) ELDK-4.2 with gcc-4.2.x ?
Are you sure your toolchain works correct with -pie?
The code is moved upwards, but that code still uses the data at d. This results another problem: Some parts in the code are assuming that d is cleared (set to zero in start.S). But what start.S does it to clear the new location (z in the picture below).
| d cz|
which is OK.
Because the code (c) still uses the data (bss) in d and not in z, some hard to find errors might occur because the used data isn't set to zero as required.
Yep, an that is, what you(we?) have to find out, why this not works with your toolchain!
I have almost no knowledge about how gcc and the binutils are handling relocation, therfore I can't help much further here. What I think is part of the problem, is that -fPIC was removed. Using -pie in LDFLAGS might be used to get relocatable code, but the data will not be relocated. And I would wonder if that is possible without instructing the compiler to build stuff for relocation (-fPIC).
Try to find out, why -pie not works with your tollchain!
bye, Heiko