[uClinux-dev] arm uclinux toolchain - source code?

Thuys, Michiel michiel.thuys at intersil.com
Thu Nov 8 03:38:17 EST 2001


Hi Adrian,

We have worked here for some time with the Aplio toolchain for
development on our ARM9 boards with the -disable-got option. To be
honest, it gave us headaches because of all kinds of compilation
problems (variables that were not initialized properly). We decided to
try and switch off the disable-got option to see how that worked. It
turned out to cost only a little extra memory due to the GOT, but solved
all our compiler related problems. Therefore, I would suggest you first
consider what you need the PIC without GOT option for, before you start
implementing it (unless of course you are a GCC expert ;).

Michiel

> -----Original Message-----
> From: Adrian von Bidder [mailto:avbidder at acter.ch]
> Sent: donderdag 8 november 2001 9:00
> To: uclinux-dev at geekcreek.net
> Cc: uclinux-dev at geekcreek.net
> Subject: Re: [uClinux-dev] arm uclinux toolchain - source code?
> 
> 
> Thierry Durand wrote:
> > 
> > Which gcc version are you using ? There are some guys here 
> working with
> > 3.0.1 on AT91, they are happy with it. I guess they didn't 
> dive into the
> > generated assembly, but relocation obviously seems to work.
> 
> gcc-2.96, working, as I said, on gcc-3.0.2
> 
> 'normal' relocation with GOT-table works ok (I assume - we don't use
> it).
> 
> What I couldn't manage was:
> code is addressed as: jump address == pc + offset stored in a constant
> in the 		text segment
> data is addressed as: address of data == r9 + offset stored in a
> constant in
> 	the text segment.
> 
> What normal GOT relocation does:
> address =  *(pic base register r9 + offset stored in constant 
> in .text)
> (actually this would be the -msingle-pic-base case)
> 
> note the extra indirection. It's leaving that away which gives me the
> headaches. (No, I can't just link statically, since this wants the
> linker to resolve *all* adresses to absolute values, leaving away both
> indirections.)
> 
> greets from Zürich
> -- vbi
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