Re: [PATCH v2 bpf-next 00/14] bpf: Support calling kernel function

[Martin KaFai Lau]

On Sun, Mar 28, 2021 at 01:13:35PM -0700, Cong Wang wrote:
> On Sat, Mar 27, 2021 at 3:54 PM Alexei Starovoitov
> <alexei.starovoi...@gmail.com> wrote:
> >
> > On Sat, Mar 27, 2021 at 3:08 PM Cong Wang <xiyou.wangc...@gmail.com> wrote:
> > >   BTFIDS  vmlinux
> > > FAILED unresolved symbol cubictcp_state
> > > make: *** [Makefile:1199: vmlinux] Error 255
> > >
> > > I suspect it is related to the kernel config or linker version.
> > >
> > > # grep TCP_CONG .config
> > > CONFIG_TCP_CONG_ADVANCED=y
> > > CONFIG_TCP_CONG_BIC=m
> > > CONFIG_TCP_CONG_CUBIC=y
> > ..
> > >
> > > # pahole --version
> > > v1.17
> >
> > That is the most likely reason.
> > In lib/Kconfig.debug
> > we have pahole >= 1.19 requirement for BTF in modules.
> > Though your config has CUBIC=y I suspect something odd goes on.
> > Could you please try the latest pahole 1.20 ?
> 
> Sure, I will give it a try tomorrow, I am not in control of the CI I ran.
Could you also check the CONFIG_DYNAMIC_FTRACE and also try 'y' if it
is not set?