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Date: Wed, 10 Sep 2014 11:03:10 +0200
From: Daniel Borkmann <dborkman@redhat.com>
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To: Alexei Starovoitov <ast@plumgrid.com>
CC: "David S. Miller" <davem@davemloft.net>, Ingo Molnar <mingo@kernel.org>,
        Linus Torvalds <torvalds@linuxfoundation.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Steven Rostedt <rostedt@goodmis.org>,
        Hannes Frederic Sowa <hannes@stressinduktion.org>,
        Chema Gonzalez <chema@google.com>, Eric Dumazet <edumazet@google.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andrew Morton <akpm@linuxfoundation.org>,
        Kees Cook <keescook@chromium.org>, linux-api@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v11 net-next 00/12] eBPF syscall, verifier, testsuite
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On 09/10/2014 07:09 AM, Alexei Starovoitov wrote:
...
>             struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
>                 int map_fd;
>                 void *key;
>                 union {
>                     void *value;
>                     void *next_key;
>                 };
>             };
>
>             struct { /* anonymous struct used by BPF_PROG_LOAD command */
>                 enum bpf_prog_type    prog_type;
>                 __u32                 insn_cnt;
>                 const struct bpf_insn *insns;
>                 const char            *license;
>                 __u32                 log_level; /* verbosity level of eBPF verifier */
>                 __u32                 log_size;  /* size of user buffer */
>                 void                  *log_buf;  /* user supplied buffer */

What is log buffer? Would that mean the verifier will return an error
string if the program will not pass it, or if not, what other data?
I think the man page is missing how to examine the returned verifier
log buffer data.