Date: Tue, 10 Mar 2020 11:08:22 -0700 From: Conrad Meyer <cem@freebsd.org> To: Willem Jan Withagen <wjw@digiware.nl> Cc: "freebsd-virtualization@freebsd.org" <virtualization@freebsd.org>, FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: [RFC] Adding a Rados block driver to bhyve Message-ID: <CAG6CVpXDunwwg-oXHFaZrpuiFWxPY5XJ5Xvf3%2BB=wJ7n3Ao2BA@mail.gmail.com> In-Reply-To: <ba937caf-ce4b-eeb9-8915-f9b9910aa711@digiware.nl> References: <9c7a8dea-ac8a-4d17-ed33-b6c4e882add8@digiware.nl> <CAOtMX2iyhS230oCysYx3YC72B8TwFrrkcXtCoMCYK85KbFORaQ@mail.gmail.com> <c2090191-920b-3d2f-f797-75a448b18ad6@digiware.nl> <CAOtMX2iwJ1_VVDXOnSP6nui-JcYMwndXMex8fxtyi6qEikUX8A@mail.gmail.com> <936ed7c2-99d2-5df8-de3f-f64f28d2ba6f@digiware.nl> <CAOtMX2gKkh=Fik9wjHoAx9Gt9zwePMjmRaGP63eE2quNTmyDGw@mail.gmail.com> <ba937caf-ce4b-eeb9-8915-f9b9910aa711@digiware.nl>
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On Tue, Mar 10, 2020 at 9:28 AM Willem Jan Withagen <wjw@digiware.nl> wrote: > >> problem that libblock_rbd.so is stripped in such a way that > >> the symbol I need is removed. > > > So either I'm doing it the wrong way, like special options on the > > symbols oid. > > > However, I think there's something wrong with your > > library, too. The library should be usable even if it's stripped. Yes, strip only removes local symbols (.symtab), not exported ones (.dynsym). > I checked with objdump, and the symbol that I need is definitly not > present in the stripped version. How are you defining the symbol intended for export? Is the symbol a function or data? Does the compiler flag -fvisibility=hidden get used? Which symbol is missing and what are the symptoms? > And it does not really matter if I declare it static or not. Not declaring it "static" is necessary, if not sufficient. Looking at your code on github, here are some issues: * In block_if.h, you define an object blocklocal_backend. This is a header, and every compilation unit that pulls in the header will get its own copy of blocklocal_backend. You probably want 'extern block_backend_t blocklocal_backend;' instead. * You SET_DECLARE block_backend_set in block_if.c, but I think it needs to be in block_if.h. * There is some weirdness around linker sets being removed by the linker if they are empty, so you may want to add blockbackend_local to the linker set in the main program. (It's unclear to me why blockbackend_local is treated specially regardless.) However, I'm not quite sure why DATA_SET() in block_rbd.c is not creating __start_set_block_backend_set / __stop_set_block_backend_set exported symbols. As Alan asked, please provide 'nm -D foo.so'. Best, Conrad
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