> On 14. Apr 2023, at 16:57, Ard Biesheuvel <a...@kernel.org> wrote: > > On Fri, 14 Apr 2023 at 16:37, Gerd Hoffmann <kra...@redhat.com> wrote: >> >>> On Fri, Apr 14, 2023 at 12:29:21PM +0000, Marvin Häuser wrote: >>> Hi Gerd, >>> >>> Thanks for your effort! >>> >>> Sorry, but I *really* dislike this “BASETOOLS” notion. There might be >>> external tools that also want to use the header (like we do with AUDK) >>> and also edk2 supports host-based unit tests. Imo the macro name >>> should be generic, like “HOST_OS” or “USERLAND” or something (I’m bad >>> with names :) ). >> >> I'm certainly open to better naming ideas. >> >> Underlying problem is that x64 ProcessorBind.h sets visibility to >> hidden (anyone knows why?). > > Yes. Toolchains tend to assume that you are generating code for a > shared library once you enabled -fpic, and this results in lots of > pointless indirections via the GOT.
Unless Safari search is borked (this indeed sometimes happens, I swear :-) ), -fpic is never passed, only -fpie. Should be mostly preemption, I guess. > (This has to do with the > copy-on-write footprint of shared library pages, as a GOT tends to > gather all relocated quantities in a small region of memory. It is > also related to ELF symbol preemption, which is another thing we don't > give a ^$& about). > > *However*, recent linkers do a better job getting rid of these GOT > references at link time, once you pass the --relax option. On X64 in > particular, there are special, relaxable GOTPCREL relocations now that > will not result in to symbol references via the GOT if the linker > notices that the symbol in question is never preempted and not > provided externally. > > So it is worth an experiment whether we still need this to begin with. > >> Seems to be fine for freestanding binaries, >> but when linking host tools against shared libraries things break. For >> some reason on ubuntu only, fedora works fine (both gcc and clang). >> >> Automatically detecting freestanding vs. hosted would be even better, >> anyone knows whenever there is a define which can be used for this? At >> least the gcc man page doesn't mention any ... >> > > ard@gambale:~/linux-build-x86$ gcc -dM -E -o - -xc - <<< ""|grep HOSTED > #define __STDC_HOSTED__ 1 > ard@gambale:~/linux-build-x86$ gcc -ffreestanding -dM -E -o - -xc - > <<< ""|grep HOSTED > #define __STDC_HOSTED__ 0 You are godsend. :) Best regards, Marvin -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#103009): https://edk2.groups.io/g/devel/message/103009 Mute This Topic: https://groups.io/mt/98257896/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
