Re: [PATCH] CMakeLists.txt: Add STATIC_LINK option

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Mon, Oct 18, 2021 at 10:57:43AM +0100, Douglas Raillard escreveu:
> On 10/15/21 3:20 PM, Arnaldo Carvalho de Melo wrote:
> > Em Fri, Oct 15, 2021 at 10:22:43AM -0300, Arnaldo Carvalho de Melo escreveu:
> > > Em Fri, Oct 15, 2021 at 10:18:41AM -0300, Arnaldo Carvalho de Melo escreveu:
> > > CMake Error at cmake/modules/FindDWARF.cmake:103 (message):
> > >    Could NOT find some ELF and DWARF libraries, please install the missing
> > >    packages
> > > Call Stack (most recent call first):
> > >    CMakeLists.txt:64 (find_package)
> > > 
> > > 
> > > -- Configuring incomplete, errors occurred!
> > > See also "/var/home/acme/git/pahole/build/CMakeFiles/CMakeOutput.log".
> > > ⬢[acme@toolbox build]$
> > > 
> > > Which means I don't have those static library files, will try installing
> > > them.
> > 
> > I'm trying with the latest fedora that comes with static libraries,
> > fedora:32, and there I noticed that we need to look for libzstd as well,
> > I added it manually to:
> > 
> > target_link_libraries(dwarves ${DWARF_LIBRARIES} ${ZLIB_LIBRARIES} ${LIBBPF_LIBRARIES} ${ARGP_LIBRARY} ${OBSTACK_LIBRARY} ${BZ2_LIBRARY} ${LZMA_LIBRARY} -lzstd)
> > 
> > [root@cc85f3a7b96f dwarves-1.22]# rpm -qa | grep -- -static
> > zlib-static-1.2.11-21.fc32.x86_64
> > glibc-static-2.31-6.fc32.x86_64
> > elfutils-devel-static-0.183-1.fc32.x86_64
> > xz-static-5.2.5-1.fc32.x86_64
> > libxcrypt-static-4.4.20-2.fc32.x86_64
> > libzstd-static-1.4.9-1.fc32.x86_64
> > elfutils-libelf-devel-static-0.183-1.fc32.x86_64
> > bzip2-static-1.0.8-2.fc32.x86_64
> > [root@cc85f3a7b96f dwarves-1.22]# cat /etc/fedora-release
> > Fedora release 32 (Thirty Two)
> > [root@cc85f3a7b96f dwarves-1.22]#
> > 
> > now I'm at:
> > 
> > /usr/bin/ld: /usr/lib/gcc/x86_64-redhat-linux/10/../../../../lib64/libdw.a(debuginfod-client.o): in function `__libdwfl_debuginfod_init':
> > (.text.startup[.text.startup.group]+0x1b): undefined reference to `dlopen'
> > /usr/bin/ld: (.text.startup[.text.startup.group]+0x36): undefined reference to `dlsym'
> > /usr/bin/ld: (.text.startup[.text.startup.group]+0x4f): undefined reference to `dlsym'
> > /usr/bin/ld: (.text.startup[.text.startup.group]+0x68): undefined reference to `dlsym'
> > /usr/bin/ld: (.text.startup[.text.startup.group]+0x81): undefined reference to `dlsym'
> > /usr/bin/ld: (.text.startup[.text.startup.group]+0xe0): undefined reference to `dlclose'
> > 
> > that needs some more magic that I already forgot :-\
> 
> When trying on Ubuntu it also appeared that find_library() for libebl
> was also needed, but not on Alpine Linux so I did not include it, as it
> does not seem necessary on Alpine. I'm not sure how we want to go about
> these:
> 1) Take the union of all the dependencies that seem to be necessary and
> deal gracefully in CMakeLists.txt with failure to find a lib. This will
> result in linker error if a lib is actually necessary and not found.
> 2) Select a blessed distro for static building and only maintain that
> 3) Find some cmake builtin "magic" so that the user can point at
> existing lib that seem to not be detected on their distro. I'm quite
> rusty in cmake so maybe there is a better way than sprinkling
> find_library() everywhere.
> 
> So far I opted for approach 2) with Alpine, as building on e.g. Ubuntu
> will not work in any case, because glibc does not support static linking
> (it kind of does until it does not anymore). Alpine uses the musl libc
> which supports static linking.
> 
> As for the dlopen/dlsym/dlclose issue I'm not sure. Maybe these symbols
> are just not present in static glibc ? The binary I produced on Alpine
> did not seem to segfault [1]. If you want to give it a go, this scripts
> set it up in ~20s:
> https://github.com/alpinelinux/alpine-chroot-install
> 
> Packages: bash gcc git make cmake musl-dev zlib-static bzip2-static
> libelf-static libbpf-dev musl-obstack-dev argp-standalone linux-headers

I'll try with this later, thing is, I want to build on the CI for pahole
that Andrii put in place in the libbpf repo, so we need to check how to
build this static build.

- Arnaldo
 
> 
> [1] pahole static binaries:
> https://github.com/ARM-software/lisa/pull/1740/files
> > 
> > But now out to lunch.
> > 
> > - Arnaldo
> > 
> Cheer,
> Douglas
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-- 

- Arnaldo