Bug#837478: Static libraries - PIC or PIE?
On Sat, Nov 19, 2016 at 07:12:19PM -0700, Phillip Hellewell wrote:
> Consider this use case for an end user with 64-bit Debian 9:
> - Compiles an executable with gcc, linking a few libraries like ICU,
> openssl, bz2, etc. Works fine.
> - Now tries to link a few of the libraries statically (e.g.,
> libicuuc.a). ld blows up with a bunch of relocation R_X86_64_32S, blah
> blah blah, recompile with -fPIC errors.
>
> This was me a few hours ago, when I found about all this the hard way.
>
> Problem is, an end user has absolutely no idea what they're doing wrong or
> how to fix it. They have no idea that GCC 6 in Debian 9 now has PIE on by
> default. They have no idea what PIE is. They have no idea if they must
> recompile their own code with -fPIC or rebuild the 3rdparty libraries with
> it. They do not believe they should have to rebuild 3rdparty libraries
> (why isn't the distro's version of them working)? They also have no idea
> that they can work around the problem using -no-pie if they don't care
> about PIE.
>
> All they know is that for some reason they can't link most libraries
> statically without getting a bunch of weird errors. It could take hours of
> research to figure out a workaround like -no-pie.
>
> Given that GCC 6 on Debian 9 now does PIE executables by default, I think
> it becomes very necessary to consider that Debian out to build all static
> libraries with -fPIE (or -fPIC). Otherwise you're going to get thousands
> and thousands of users having no clue why they can't link anything
> statically. Plus if you did that you wouldn't have to build everything
> twice. Win-Win !!! So why not?
Worth, PIE code is measurably slower than normal code.
The fact that the Debian default compiler generate slow code is quite annoying
for HPC and anything where performance comparaison are important.
At the very least this break the principle of leat surprise. -fPIE
should only be activated by default when building Debian package, not
for users compiling their own code.
Cheers,
--
Bill. <ballombe@debian.org>
Imagine a large red swirl here.
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