Re: [PATCH dwarves] Respect CMAKE_INSTALL_LIBDIR

["Olson, Matthew" <matthew.olson@intel.com>]

On Mon, Nov 25, 2024 at 05:04:53PM +0000, Alan Maguire wrote:
> On 25/11/2024 15:51, Ben Olson wrote:
> > This patch changes the `cmake` configuration to honor `CMAKE_INSTALL_LIBDIR`
> > and use `lib` by default so that installations match the conventional placement
> > of libraries. For example, it will now install `libdwarves.so` into
> >  `/usr/local/lib` instead of `/usr/local` directly.
> > 
> 
> What about distros that use /usr/[local/]/lib64 for 64-bit libraries? It
> seems like CMAKE_INSTALL_LIBDIR does the right thing there also by
> default, can you confirm? If that is indeed the case, it would be good
> to amend the commit description to not be "lib"-specific, and say
> something like "CMAKE_INSTALL_LIBDIR ensures installations match the
> conventional placement of libraries - /usr/local/lib on some systems,
> /usr/local/li64 on others. Otherwise folks might think they need to
> override this when they probably don't. Thanks!

Yes, it should respect `lib64` - we've just tested on both Arch and Fedora.
On Arch, `lib64` is just a symlink to `lib`, and this patch places things
in `lib`. On Fedora, it places things in `lib64`. Just noticed that we do
have to include a built-in CMake module for it to work properly, though.
I'll add that in v2 along with the commit message change.

Thank you!

> 
> Alan
> 
> > Signed-off-by: Brandon Kammerdiener <brandon.kammerdiener@intel.com>
> > Signed-off-by: Ben Olson <matthew.olson@intel.com>
> > ---
> > 
> > This patch addresses this issue: https://github.com/acmel/dwarves/issues/48
> > 
> >  CMakeLists.txt | 17 ++++-------------
> >  README         |  3 +--
> >  2 files changed, 5 insertions(+), 15 deletions(-)
> > 
> > diff --git a/CMakeLists.txt b/CMakeLists.txt
> > index 8ca1bf2..b2c8057 100644
> > --- a/CMakeLists.txt
> > +++ b/CMakeLists.txt
> > @@ -21,18 +21,7 @@ else()
> >  	LINK_DIRECTORIES(${LIBBPF_LIBRARY_DIRS})
> >  endif()
> >  
> > -# Try to parse this later, Helio just showed me a KDE4 example to support
> > -# x86-64 builds.
> > -# the following are directories where stuff will be installed to
> > -set(__LIB "" CACHE STRING "Define suffix of directory name (32/64)" )
> > -
> > -macro(_set_fancy _var _value _comment)
> > -	if (NOT DEFINED ${_var})
> > -		set(${_var} ${_value})
> > -	else (NOT DEFINED ${_var})
> > -		set(${_var} "${${_var}}" CACHE PATH "${_comment}")
> > -	endif (NOT DEFINED ${_var})
> > -endmacro(_set_fancy)
> > +set(CMAKE_INSTALL_LIBDIR "lib" CACHE STRING "libdir name")
> >  
> >  # where to look first for cmake modules,
> >  # before ${CMAKE_ROOT}/Modules/ is checked
> > @@ -84,7 +73,9 @@ if(NOT LIBBPF_FOUND AND NOT EXISTS "${PROJECT_SOURCE_DIR}/lib/bpf/src/btf.h")
> >  	message(FATAL_ERROR "The submodules were not downloaded! GIT_SUBMODULE was turned off or failed. Please update submodules and try again.")
> >  endif()
> >  
> > -_set_fancy(LIB_INSTALL_DIR "${EXEC_INSTALL_PREFIX}${CMAKE_INSTALL_PREFIX}/${__LIB}" "libdir")
> > +if (NOT DEFINED LIB_INSTALL_DIR)
> > +    set(LIB_INSTALL_DIR "${EXEC_INSTALL_PREFIX}${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}")
> > +endif()
> >  
> >  # libbpf uses reallocarray, which is not available in all versions of glibc
> >  # libbpf's include/tools/libc_compat.h provides implementation, but needs
> > diff --git a/README b/README
> > index f9aeef7..0627872 100644
> > --- a/README
> > +++ b/README
> > @@ -3,8 +3,7 @@ Build instructions:
> >  1. install cmake
> >  2. mkdir build
> >  3. cd build
> > -4. cmake -D__LIB=lib ..
> > -5. make install
> > +4. make install
> >  
> >  cmake Options:
> >    -DBUILD_SHARED_LIBS
>