Binary compatibility loss regarding errno
H. J. Lu
hjl@lucon.org
Mon Dec 30 10:17:00 GMT 2002
On Fri, Dec 27, 2002 at 01:47:45PM -0800, Roland McGrath wrote:
Content-Description: message body text
> > On Fri, Dec 27, 2002 at 01:09:48PM -0800, Roland McGrath wrote:
> > > I consider this an ld bug. It's invalid to produce other than an
> > > R_386_GLOB_DAT reloc for a data object that is exported at runtime.
> >
> > If you have a small testcase, I will take a look.
>
> $ gcc -shared -o loser.so loser.c -Wl,--version-script=loser.v
> $ readelf -r loser.so
>
> Note no reloc using the symbol `x'.
>
Content-Description: C source file for ld bug test case
> int x;
> asm(".symver x,x@VERS_1");
> int foo() { return x; }
I believe ld works as expected. Basically
int foo() { return x; }
will use the definition of `x', which is the original symbol, not the
versioned one. Please try
extern int x;
int _x __attribute__((section (".bss")));
asm(".symver _x,x@VERS_1");
int foo() { return x; }
When you use `.symver NAME,NAME2@NODENAME', NAME should be different
from NAME2. Otherwise, you will get many surprises.
H.J.
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