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Date:   Wed, 20 Mar 2019 14:23:46 -0700
From:   Jakub Kicinski <jakub.kicinski@netronome.com>
To:     Alban Crequy <alban.crequy@gmail.com>
Cc:     ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, alban@kinvolk.io, iago@kinvolk.io
Subject: Re: [PATCH bpf-next v1 4/7] tools: bpftool: implement map exec
 command
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In-Reply-To: <20190320173332.18105-4-alban@kinvolk.io>
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        <20190320173332.18105-4-alban@kinvolk.io>
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On Wed, 20 Mar 2019 18:33:29 +0100, Alban Crequy wrote:
> From: Alban Crequy <alban@kinvolk.io>
> 
> The map exec commands allows to open an existing map and pass the file
> descriptor to a child process. This enables applications to use an
> existing BPF map even when they don't support bpffs.
> 
> Example of usage:
>     # bpftool map exec pinned /sys/fs/bpf/foo fd 99 cmd -- readlink /proc/self/fd/99
>     anon_inode:bpf-map

Would you mind telling us a little more about the use for this feature?
It seems fairly limited.  If it's about probing objects (finding out if
they are a map or a program) perhaps we can add a command just for that?

(I guess bpftool -f isn't really the cleanest way of getting at that
info.)

> Documentation and bash completion updated as well.
> 
> Signed-off-by: Alban Crequy <alban@kinvolk.io>