On Mon, Jan 11, 2021 at 5:05 PM Yonghong Song <yhs@xxxxxx> wrote: > > > > On 1/11/21 4:48 AM, Sedat Dilek wrote: > > Hi BPF maintainers and Mashiro, > > > > Debian started to use CONFIG_DEBUG_INFO_BTF=y. > > > > My kernel-build fails like this: > > > > + info BTFIDS vmlinux > > + [ != silent_ ] > > + printf %-7s %s\n BTFIDS vmlinux > > BTFIDS vmlinux > > + ./tools/bpf/resolve_btfids/resolve_btfids vmlinux > > FAILED: load BTF from vmlinux: Invalid argument > > > > The root cause is my selfmade LLVM toolchain has no BPF support. > > linux build should depend on LLVM toolchain unless you use LLVM to build > kernel. > > > > > $ which llc > > /home/dileks/src/llvm-toolchain/install/bin/llc > > > > $ llc --version > > LLVM (http://llvm.org/ ): > > LLVM version 11.0.1 > > Optimized build. > > Default target: x86_64-unknown-linux-gnu > > Host CPU: sandybridge > > > > Registered Targets: > > x86 - 32-bit X86: Pentium-Pro and above > > x86-64 - 64-bit X86: EM64T and AMD64 > > > > Debian's llc-11 shows me BPF support is built-in. > > > > I see the breakag approx. 3 hours after the start of my kernel-build - > > in the stage "vmlinux". > > After 2 faulures in my build (2x 3 hours of build-time) I have still > > no finished Linux v5.11-rc3 kernel. > > This is a bit frustrating. > > You mean "BTFIDS vmlinux" takes more than 3 hours here? > Maybe a bug in resolve_btfids due to somehow different ELF format > resolve_btfids need to handle? > [ CC Tom ] OMG no. 3 hours up to running scripts/link-vmlinux.sh. In the meantime I have built a LLVM toolchain with BPF support. $ llc --version LLVM (http://llvm.org/): LLVM version 11.0.1 Optimized build. Default target: x86_64-unknown-linux-gnu Host CPU: sandybridge Registered Targets: bpf - BPF (host endian) bpfeb - BPF (big endian) bpfel - BPF (little endian) x86 - 32-bit X86: Pentium-Pro and above x86-64 - 64-bit X86: EM64T and AMD64 Tom reported BTF issues with pahole v1.19 (see [2] and [3]): "I ran into this same bug trying to build the Fedora kernel. The problem is that pahole segfaults at: scripts/link-vmlinux.sh:131. This looks to me like a bug in pahole." pahole ToT (post v1.19) offers some BTF fixes - I have manually build and use it. Building a new Linux-kernel... - Sedat - [1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/ [2] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758026878 [3] https://github.com/ClangBuiltLinux/tc-build/issues/129#issuecomment-758056553 > > > > What about doing pre-checks - means before doing a single line of > > compilation - to check for: > > 1. Required binaries > > 2. Required support of whatever feature in compiler, linker, toolchain etc. > > > > Recently, I fell over depmod binary not found in my PATH - in one of > > the last steps (modfinal) of the kernel build. > > > > Any ideas to improve the situation? > > ( ...and please no RTFM, see links below. ) > > > > Thanks. > > > > Regards, > > - Sedat - > > > > > > [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh#n144 > > [1] https://salsa.debian.org/kernel-team/linux/-/commit/929891281c61ce4403ddd869664c949692644a2f > > [2] https://www.kernel.org/doc/html/latest/bpf/bpf_devel_QA.html?highlight=pahole#llvm > > [3] https://www.kernel.org/doc/html/latest/bpf/btf.html?highlight=pahole#btf-generation > >
