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Date: Sat, 11 Jan 2014 11:40:32 -0600
From: Rob Landley <rob@...dley.net>
To: Rich Felker <dalias@...ifal.cx>
Cc: musl@...ts.openwall.com
Subject: Re: libgcc --disable-shared test case
On 10/17/2013 01:09:13 AM, Rich Felker wrote:
> On i386 or any arch where libgcc functions are needed for 64-bit
> division, the following should reproduce the failure if libgcc was
> built with --disable-shared (which disables visibility):
>
> gcc -O2 -shared -o libfoo.so lib_v1.c
> gcc -O2 main.c ./libfoo.so
> ./a.out # ok
> gcc -O2 -shared -o libfoo.so lib_v2.c
> ./a.out # fails with symbol errors
>
> Rich
lib_v1.c:
long long foo(long long x) { return x/10; }
lib_v2.c:
long long foo(long long x) { return x/16; }
main.c:
#include <stdio.h>
extern long long foo(long long);
int main() { printf("%lld\n", foo(100)/10); }
Ok, I just tested this again. With lib_v1.c, the one built with my
simple-cross-compiler toolchain printed 1, and the lib_v2.c printed 0.
(I believe you said the error was a link failure?)
I had to copy the resulting a.out and libfoo.so into
simple-root-filesystem (which was built with the simple cross compiler
and doesn't contain a native compiler) to run it in a chroot because
the host hasn't got uClibc libraries installed in it, hence no
libc.so.0 for the dynamic link...
Looks like my toolchain doesn't exhibit this behavior? (Not after I
hacked the hell out of the libgcc.a build, anyway...)
(I'm sure I tested this before, but didn't write the result down.
There's a reason I blog to myself so much when I'm not buried by
$DAYJOB...)
Rob
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