On 08/22/17 16:15, Paolo Bonzini wrote: > On 22/08/2017 16:03, Ard Biesheuvel wrote: >> On 22 August 2017 at 14:27, Paolo Bonzini <pbonz...@redhat.com> wrote: >>> On 22/08/2017 13:59, Laszlo Ersek wrote: >>>> This seems to suggest that "-pie" is the *master* switch (used only when >>>> linking), and "-fpie" is a *prerequisite* for it (to be used both when >>>> linking and compiling). Is this right? >>>> >>>> If so, then I think this is a gcc usability bug. We don't generally >>>> start our thinking from the linker side. The above implies that the >>>> simple (hosted) command line: >>>> >>>> $ gcc -o example -fpie source1.c source2.c >>>> >>>> could also result in miscompilation, because "-pie" is not given, only >>>> "-fpie". >>> >>> No, GCC should add -pie on its own. >>> >> >> I disagree. PIE linking and PIE code generation are two completely >> different things. > > What I'm saying is that GCC should add -pie on its own if you add -fpie > to the linker command line.
Yes, that's my point, from a usability perspective. While I hope to understand Ard's explanation (and it seems to confirm that "-fpie" at compilation is a 'prerequisite' for "-pie" at linking), again, this simply isn't how humans think about building binaries. If we are required to call the compiler frontend for all purposes -- and we seem to be required --, then we shouldn't have to express the same end goal in different ways for different link-editing phases. > But that would require changes to the > compiler driver. > > That said, the extra "-Wl," in "-Wl,-pie" is not necessary; the compiler > driver knows "-pie" and swallows it when compiling (and passes it to the > linker). Now *that* I can get behind. If this works, then please let us do it -- replace "-fpie" with "-pie" in GCC44_X64_CC_FLAGS, and add no "-Wl," stuff to any DLINK defines. Thanks! Laszlo _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
