[Beowulf] broken binutils (was: Redmond is at it, again)

Michael Will mwill at penguincomputing.com
Fri Jun 18 17:12:13 EDT 2004


Why again did you prefer a[....] over *a = malloc(...) ? 

Michael
On Friday 18 June 2004 01:40 pm, Martin Siegert wrote:
> On Thu, Jun 17, 2004 at 10:34:28PM -0700, Greg Lindahl wrote:
> > ... until the day that it actually is a kernel or glibc bug. "Oh, we
> > don't really support that OS, you have to upgrade to something
> > different." "I'm sorry, but that distro has a broken binutils, so
> > programs with large common blocks simply can't be compiled, and we
> > aren't going to even think about doing a workaround because not enough
> > of our users use that distro." And it goes downhill from there.
> >
> > -- greg
>
> Since you mentioned this: I am struggling with binutils right now.
> Basically I am considering the following program:
>
> double a[117403096];
> int main(){}
>
> gdb tells me that &a[117403095] is at 0x3ffffff8 and ldd tells me
> that ld-linux.so.2 is at 0x40000000 (as always).
>
> Thus, when I compile
>
> double a[117403097];
> int main(){}
>
> ldd and a.out segfault because &a[117403096] overwrites the address
> of the run-time linker (on your system you may have to change 117403096
> a little bit). Arrgh. This means that you can only use about 1GB of
> memory in programs with statically allocated arrays (which is mostly
> a problem with old fashioned F77 programs). The workaround is to compile
> with the -static flag so that you actually can safely overwrite the
> 0x40000000 address.
>
> Now on a SuSE-9.1 box (with binutils-2.15.90.0.1.1, gcc-3.3.3, 2.6.4
> kernel) This problem disappears: When I compile
>
> double a[117403097];
> int main(){}
>
> and the run "ldd a.out" it says "not a dynamic executable" even when
> compiling without the -static flag. My first guess was that I just
> have to upgrade ld to the 2.15 version, but after upgrading binutils
> on a SuSE-9.0 box (gcc-3.3.1, 2.4.26 kernel) to exactly the same
> 2.15.90.0.1.1 version this does not fix the problem, i.e., ldd and a.out
> still segfault. Thus: what is broken here? Do I need to upgrade gcc and/or
> the kernel as well?
>
> Cheers,
> Martin
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-- 
Michael Will, Linux Sales Engineer
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