From: Daniel Borkmann <dborkman@redhat.com>
To: Alexei Starovoitov <ast@plumgrid.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Chema Gonzalez <chema@google.com>,
Eric Dumazet <edumazet@google.com>,
Network Development <netdev@vger.kernel.org>
Subject: Re: [PATCH net-next] net: filter: cleanup A/X name usage
Date: Tue, 10 Jun 2014 09:29:00 +0200 [thread overview]
Message-ID: <5396B3BC.30504@redhat.com> (raw)
In-Reply-To: <CAMEtUux+sj7o9=57JAaHvGJXJmfuyRKb+dFL_3ZdkmAoHy9XzA@mail.gmail.com>
On 06/09/2014 09:25 PM, Alexei Starovoitov wrote:
...
> Point taken. Will do more thorough documentation patch to
> explain eBPF instruction set a bit better. Mainly to clarify encoding.
> eBPF tried to be as close as possible to classic BPF, since I thought
> it will make it easier to understand. That's why I reused A/X in names
> and bits in opcode encoding.
> In classic, A is accumulator and X is indeX. In eBPF I thought
> calling destination register 'a_reg' made sense, since it would
> indicate that this 'a_reg' is a register that is used as 'accumulator'
> in the instruction. Like in "bpf_add R2, 5", R2 is Accumulator.
> In "bpf_add R2, R3", R2 is Accumulator and R3 is indeX
> and BPF_X bit in opcode indicates whether 'x_reg' field of the
> instruction is used. Unfortunately that decision caused the whole
> A/X naming confusion, that this patch is addressing.
> src_reg and dst_reg are indeed better names.
I think both naming conventions (before/after) are fine, imho.
next prev parent reply other threads:[~2014-06-10 7:29 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-06 21:46 [PATCH net-next] net: filter: cleanup A/X name usage Alexei Starovoitov
2014-06-08 20:21 ` Daniel Borkmann
2014-06-09 17:10 ` Chema Gonzalez
2014-06-09 19:25 ` Alexei Starovoitov
2014-06-10 7:29 ` Daniel Borkmann [this message]
2014-06-11 7:13 ` David Miller
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