Build error “libatomic not found” on Ubuntu LTS release (24.04) #132

1. 
   ryanofsky commented at 5:33 pm on January 23, 2025: collaborator

   Originally posted by @fanquake in https://github.com/bitcoin/bitcoin/issues/30975#issuecomment-2610191420

   Basic usage of building libmultiprocess yourself, on the current Ubuntu LTS release (24.04), for use with Core, doesn’t currently work:

    0<libmultiprocess compiled & installed following instructions>
    1cmake -B build -DWITH_MULTIPROCESS=ON
    2-- The CXX compiler identification is GNU 13.3.0
    3-- Detecting CXX compiler ABI info
    4-- Detecting CXX compiler ABI info - done
    5-- Check for working CXX compiler: /usr/bin/c++ - skipped
    6-- Detecting CXX compile features
    7-- Detecting CXX compile features - done
    8-- Found SQLite3: /usr/include (found suitable version "3.45.1", minimum required is "3.7.17") 
    9-- Looking for __atomic_load_8 in atomic
   10-- Looking for __atomic_load_8 in atomic - not found
   11CMake Error at /usr/lib/aarch64-linux-gnu/cmake/CapnProto/CapnProtoConfig.cmake:108 (message):
   12  libatomic not found
   13Call Stack (most recent call first):
   14  /usr/share/cmake-3.28/Modules/CMakeFindDependencyMacro.cmake:76 (find_package)
   15  /usr/local/lib/cmake/Libmultiprocess/LibmultiprocessConfig.cmake:38 (find_dependency)
   16  CMakeLists.txt:146 (find_package)
   17
   18-- Configuring incomplete, errors occurred!
   

   Having to work around this was also mentioned here: https://github.com/bitcoin/bitcoin/pull/10102#issuecomment-2515554249. We can likely work around this ourselves, but something this basic should be fixed before requiring developers to use this library. Along with reporting & upstreaming fixes to what are now new (hard) dependencies for us.

2. 
   ryanofsky commented at 5:47 pm on January 23, 2025: collaborator

   To clarify, this error does not happen when running libmultiprocess cmake configuration, but when running another cmake configuration that that calls find_package(Libmultiprocess REQUIRED COMPONENTS Lib). Probably the workaround from https://github.com/chaincodelabs/libmultiprocess/pull/119 could be added to cmake/Config.cmake.in to prevent this
3. 
   ryanofsky commented at 9:07 pm on January 23, 2025: collaborator

   I tried to reproduce this and couldn’t. Then I realized I accidentally downloaded ubuntu 22.04 not 24.04. Good to know that this issue does not seem to happen with 22.04 though!

   /etc/os-release is VERSION=“22.04.5 LTS (Jammy Jellyfish)” libmultiprocess is 3b2617b3e59f55ae3501c82a62c87f393077779f bitcoin commit is d5a2ba44ba4f23fcf3b3408d28438b7c7013ba36

    0lxc launch ubuntu:jammy ubu
    1lxc image list images:  | grep -i ubuntu
    2lxc exec ubu -- /bin/bash
    3lxc exec ubu -- adduser --shell /bin/bash --ingroup sudo ubu
    4lxc exec ubu -- su - ubu
    5
    6git clone https://github.com/bitcoin/bitcoin
    7git clone https://github.com/chaincodelabs/libmultiprocess
    8sudo apt update
    9sudo apt-get install build-essential cmake pkg-config python3 libevent-dev libboost-dev libsqlite3-dev libcapnp-dev capnproto cmake-curses-gui
   10
   11cd ~/libmultiprocess
   12mkdir build
   13cd build
   14cmake ..
   15make
   16make check # Optionally build and run tests
   17sudo make install
   18
   19cd ~/bitcoin
   20cmake -B build
   21ccmake build # toggle WITH_MULTIPROCESS
   22make -j12 -C build bitcoin-node bitcoin-cli
   23
   24build/src/bitcoin-node -ipcbind=unix:cool -regtes
   25build/src/bitcoin-cli -regtest echoipc hi
   

4. ryanofsky referenced this in commit 67afc23069 on Jan 23, 2025
5. 
   ryanofsky commented at 9:31 pm on January 23, 2025: collaborator

   Was able to reproduce this problem with steps above just replacing jammy with noble and using ubuntu VERSION=“24.04.1 LTS (Noble Numbat)”

   Confirmed that applying #133 fixes it

6. ryanofsky closed this on Jan 27, 2025

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7. ryanofsky referenced this in commit 3dc1d42a7a on Jan 27, 2025

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