Stanislav Fomichev wrote: > While trying to figure out why fentry_fexit selftest doesn't pass for me > (old pahole, broken BTF), I found out that my latest patch can break vmlinux > .BTF generation. objcopy preserves section start when doing --only-section, > so there is a chance (depending on where pahole inserts .BTF section) to > have leading empty zeroes. Let's explicitly force section offset to zero. > > Before: > $ objcopy --set-section-flags .BTF=alloc -O binary \ > --only-section=.BTF vmlinux .btf.vmlinux.bin > $ xxd .btf.vmlinux.bin | head -n1 > 00000000: 0000 0000 0000 0000 0000 0000 0000 0000 ................ > > After: > $ objcopy --change-section-address .BTF=0 \ > --set-section-flags .BTF=alloc -O binary \ > --only-section=.BTF vmlinux .btf.vmlinux.bin > $ xxd .btf.vmlinux.bin | head -n1 > 00000000: 9feb 0100 1800 0000 0000 0000 80e1 1c00 ................ > ^BTF magic > > As part of this change, I'm also dropping '2>/dev/null' from objcopy > invocation to be able to catch possible other issues (objcopy doesn't > produce any warnings for me anymore, it did before with --dump-section). Agree dropping /dev/null seems like a good choice. Otherwise seems reasonable to me. Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
