> -----Original Message----- > From: Thomas Monjalon <tho...@monjalon.net> > Sent: Tuesday, January 19, 2021 5:08 PM > To: Juraj Linkeš <juraj.lin...@pantheon.tech> > Cc: david.march...@redhat.com; acon...@redhat.com; > maicolgabr...@hotmail.com; jerinjac...@gmail.com; ferruh.yi...@intel.com; > ruifeng.w...@arm.com; dev@dpdk.org; bruce.richard...@intel.com > Subject: Re: [dpdk-dev] [PATCH v4 1/3] build: add aarch64 clang to meson > cross- > compile > > 19/01/2021 09:33, Juraj Linkeš: > > Create meson cross-file arm64_armv8_linux_clang_ubuntu1804. > > Why is it specific to Ubuntu 18.04? > I don't want to add specifc cross files per distributions. > > > Use clang/LLVM toolchain with sysroot pointing to gcc cross stdlib. > > > > The sysroot path must be in the cross-file so that Clang can find the > > proper headers: > > * setting CFLAGS, LDFLAGS or -Dc_args, -Dc_link_args doesn't affect > > cross builds (only native builds). Support added in 0.51.0. > > * setting pkg-config vars only affects lib searching, not includes > > * splitting the cross-file into two (one with clang info, one with > > paths) doesn't work. Support added in 0.52.0. > > I don't understand the explanations above. > Please explain what is the bug and how it is fixed. >
I guess the missing piece is that the sysroot path is the ubuntu specific part. The explanations illustrate why we can't have a generic cross file with the current meson version - there's no way to pass the paths to cross builds. Now that I think about it, the commit message needs a rewrite - I should've mentioned that clang/llvm doesn't provide it's own standard c lib, so that has to come from elsewhere (such as gcc) and thus we have to provide the paths. > [...] > > +c_args = ['-target', 'aarch64-linux-gnu', '--sysroot', > > +'/usr/aarch64-linux-gnu'] c_link_args = ['-target', > > +'aarch64-linux-gnu', '-fuse-ld=lld', '--gcc-toolchain=/usr'] > > >
