On Mon, Nov 9, 2020 at 8:43 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote: > > On Thu, 5 Nov 2020, Andrii Nakryiko wrote: > > > Display vmlinux BTF name and kernel module names when listing available BTFs > > on the system. > > > > In human-readable output mode, module BTFs are reported with "name > > [module-name]", while vmlinux BTF will be reported as "name [vmlinux]". > > Square brackets are added by bpftool and follow kernel convention when > > displaying modules in human-readable text outputs. > > > > I had a go at testing this and all looks good, but I was curious > if "bpftool btf dump" is expected to work with module BTF? I see > the various modules in /sys/kernel/btf, but if I run: > > # bpftool btf dump file /sys/kernel/btf/ixgbe You need to specify vmlinux as a base BTF. There is a -B flag for that, added in [0]. So just add -B /sys/kernel/btf/vmlinux. I think we might want to teach bpftool to do this automatically if we see that file points at module BTF in /sys/kernel/btf, as a convenience feature. [0] https://patchwork.kernel.org/project/netdevbpf/patch/20201105043402.2530976-12-andrii@xxxxxxxxxx/ > Error: failed to load BTF from /sys/kernel/btf/ixgbe: Invalid argument > > ...while it still works for vmlinux: > > # bpftool btf dump file /sys/kernel/btf/vmlinux > [1] INT '(anon)' size=4 bits_offset=0 nr_bits=32 encoding=(none) > [2] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64 > encoding=(none) > ... > > "bpftool btf show" works for ixgbe: > > # bpftool btf show|grep ixgbe > 19: name [ixgbe] size 182074B > > Is this perhaps not expected to work yet? (I updated pahole > to the latest changes etc and BTF generation seemed to work > fine for modules during kernel build). > > For the "bpftool btf show" functionality, feel free to add > > Tested-by: Alan Maguire <alan.maguire@xxxxxxxxxx> Ok, thanks. > > Thanks! > > Alan
