Re: [PATCH bpf-next v2] bpf: Generate BTF_KIND_FLOAT when linking vmlinux

[Ilya Leoshkevich <iii@linux.ibm.com>]

On Mon, 2021-04-12 at 23:56 +0200, Ilya Leoshkevich wrote:
> pahole v1.21 supports the --btf_gen_floats flag, which makes it
> generate the information about the floating-point types [1].
> 
> Adjust link-vmlinux.sh to pass this flag to pahole in case it's
> supported, which is determined using a simple version check.
> 
> [1] https://lore.kernel.org/dwarves/YHRiXNX1JUF2Az0A@kernel.org/
> 
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> ---
>  scripts/link-vmlinux.sh | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index 3b261b0f74f0..392c7fb94d3e 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -227,8 +227,13 @@ gen_btf()
>  
>         vmlinux_link ${1}
>  
> +       local extra_paholeopt=
> +       if [ "${pahole_ver}" -ge "121" ]; then
> +               extra_paholeopt="${extra_paholeopt} --btf_gen_floats"
> +       fi
> +
>         info "BTF" ${2}
> -       LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
> +       LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J${extra_paholeopt} ${1}
>  
>         # Create ${2} which contains just .BTF section but no symbols.
> Add
>         # SHF_ALLOC because .BTF will be part of the vmlinux image. --
> strip-all

Sorry, I realized I forgot to add a changelog (it's trivial, but
still). Posting it here:

v1:
https://lore.kernel.org/bpf/20210331014356.256212-1-iii@linux.ibm.com/
v1 -> v2: Use a version check instead of probing.