[U-Boot] [patch 1/1] Remove linking to libgcc while compiling U-boot

Wolfgang Denk wd at denx.de
Sun Nov 2 21:32:40 CET 2008


Dear "Remy Bohmer",

In message <3efb10970811021218g6d30d611r479c8e800991abf4 at mail.gmail.com> you wrote:
> 
> libgcc could also expect the 'raise()' routine to pass divide-by-zero
> execeptions. (if __div0, (or __aeabi_ldiv0) is not overruled)

raise()? exceptions? In C?

> In the mean time things are getting more clear. In the ARM section of
> U-boot a large amount of (division) routines which are usually
> provided by libgcc are also implemented in the lib_arm directory. For
> many ARM boards it is therefore possible to remove linking to libgcc
> at all, and it won't hurt the resulting binary at all (because nothing
> is currently used from libgcc on ARM).

...unless you use some (probably older) tool chains  where  this  may
break.  I guess there was a readon to add these functions. We did not
do this for the fun of it.

> Some routines are still lacking in the lib_arm tree and if GCC starts
> generating code (due to some code change) that
> requires those missing routines, we now get link errors if a EABI only
> compiler is used. (If for example the eabi compiler toolchain of
> CodeSourcery is used (e.g. 2008q1) then the provided libgcc is not

> So, I agree (now) that libgcc should be used, but this is _not the
> case_ currently in the ARM tree.

I think I saw libgcc on the linker command line ?

> What I now believe that should be done is to investigate (compile
> time) what type of ABI is supported by the libgcc provided by the
> compiler, and adjust the compile settings to that ABI.

If such a thing needs to be done, it is a compiler-issue, and we do
not have to know or care about that.

Best regards,

Wolfgang Denk

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