From: Saeed Mahameed <saeed@kernel.org>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Networking <netdev@vger.kernel.org>,
Andrii Nakryiko <andrii@kernel.org>
Subject: Re: [PATCH bpf] tools/bpftool: Add/Fix support for modules btf dump
Date: Mon, 07 Dec 2020 22:45:34 -0800 [thread overview]
Message-ID: <5a86df89822ba7e4d944867916423c46ad4b7434.camel@kernel.org> (raw)
In-Reply-To: <CAEf4BzYzJuPt8Fct2pOTPjHLiiyGPQw05rFNK4d+MAJTC_itkw@mail.gmail.com>
On Mon, 2020-12-07 at 22:38 -0800, Andrii Nakryiko wrote:
> On Mon, Dec 7, 2020 at 10:26 PM Saeed Mahameed <saeed@kernel.org>
> wrote:
> > On Mon, 2020-12-07 at 19:14 -0800, Andrii Nakryiko wrote:
> > > On Sun, Dec 6, 2020 at 9:21 PM <saeed@kernel.org> wrote:
> > > > From: Saeed Mahameed <saeedm@nvidia.com>
> > > >
[...]
> > > >
> > > > I am not sure why this hasn't been added by the original
> > > > patchset
> > >
> > > because I never though of dumping module BTF by id, given there
> > > is
> > > nicely named /sys/kernel/btf/<module> :)
> > >
> >
> > What if i didn't compile my kernel with SYSFS ? a user experience
> > is a
> > user experience, there is no reason to not support dump a module
> > btf by
> > id or to have different behavior for different BTF sources.
>
> Hm... I didn't claim otherwise and didn't oppose the feature, why the
> lecture about user experience?
>
Sorry wasn't a lecture, just wanted to emphasize the motivation.
> Not having sysfs is a valid point. In such cases, if BTF dumping is
> from ID and we see that it's a module BTF, finding vmlinux BTF from
> ID
> makes sense.
>
> > I can revise this patch to support -B option and lookup vmlinux
> > file if
> > not provided for module btf dump by ids.
>
> yep
>
> > but we still need to pass base_btf to btf__get_from_id() in order
> > to
> > support that, as was done for btf__parse_split() ... :/
>
> btf__get_from_id_split() might be needed, yes.
>
> > Are you sure you don't like the current patch/libbpf API ? it is
> > pretty
> > straight forward and correct.
>
> I definitely don't like adding btf_get_kernel_id() API to libbpf.
> There is nothing special about it to warrant adding it as a public
> API. Everything we discussed can be done by bpftool.
>
What about the case where sysfs isn't available ?
we still need to find vmlinux's btf id..
next prev parent reply other threads:[~2020-12-08 6:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-07 5:20 [PATCH bpf] tools/bpftool: Add/Fix support for modules btf dump saeed
2020-12-08 3:14 ` Andrii Nakryiko
2020-12-08 6:26 ` Saeed Mahameed
2020-12-08 6:38 ` Andrii Nakryiko
2020-12-08 6:45 ` Saeed Mahameed [this message]
2020-12-08 6:48 ` Andrii Nakryiko
2020-12-08 6:52 ` Saeed Mahameed
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