netdev - Re: [PATCH v2 bpf-next 1/2] btf: separate btf creation and loading

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Message-ID: <20190206030333.lurnxegmblbxrqjw@ast-mbp>
Date:   Tue, 5 Feb 2019 19:03:35 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Andrii Nakryiko <andriin@...com>
Cc:     songliubraving@...com, yhs@...com, ast@...com, kafai@...com,
        netdev@...r.kernel.org, daniel@...earbox.next,
        andrii.nakryiko@...il.com
Subject: Re: [PATCH v2 bpf-next 1/2] btf: separate btf creation and loading

On Tue, Feb 05, 2019 at 04:29:48PM -0800, Andrii Nakryiko wrote:
> This change splits out previous btf__new functionality of constructing
> struct btf and loading it into kernel into two:
> - btf__new() just creates and initializes struct btf
> - btf__load() attempts to load existing struct btf into kernel
> 
> btf__free will still close BTF fd, if it was ever loaded successfully
> into kernel.
> 
> This change allows users of libbpf to manipulate BTF using its API,
> without the need to unnecessarily load it into kernel.
> 
> One of the intended use cases is pahole using libbpf to do DWARF to BTF
> conversion and deduplication using libbpf, while handling ELF sections
> overwrites and other concerns on its own.
> 
> Signed-off-by: Andrii Nakryiko <andriin@...com>
> Acked-by: Song Liu <songliubraving@...com>

should it be 
Fixes: 2d3feca8c44f ("bpf: btf: print map dump and lookup with btf info")
?
Even back then btf__new() was doing the loading.
So that btf support in bpftool was silently double loading btf.