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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Brendan Jackman <jackmanb@google.com>
Cc: bpf <bpf@vger.kernel.org>, "Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Andrii Nakryiko" <andrii.nakryiko@gmail.com>,
	"KP Singh" <kpsingh@chromium.org>,
	"Florent Revest" <revest@chromium.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"Björn Töpel" <bjorn.topel@gmail.com>,
	"John Fastabend" <john.fastabend@gmail.com>,
	"Yonghong Song" <yhs@fb.com>
Subject: Re: [PATCH bpf-next v7 00/11] Atomics for eBPF
Date: Thu, 14 Jan 2021 19:23:32 -0800
Message-ID: <CAADnVQJVvwoZsE1K+6qRxzF7+6CvZNzygnoBW9tZNWJELk5c=Q@mail.gmail.com> (raw)
In-Reply-To: <20210114181751.768687-1-jackmanb@google.com>

On Thu, Jan 14, 2021 at 10:18 AM Brendan Jackman <jackmanb@google.com> wrote:
>
> There's still one unresolved review comment from John[3] which I
> will resolve with a followup patch.
>
> Differences from v6->v7 [1]:
>
> * Fixed riscv build error detected by 0-day robot.

Applied.
Thanks a lot.

Please address John's request in a followup and these few issues:

- rst doesn't look correct. Example:
rst2man Documentation/networking/filter.rst >/dev/null
Documentation/networking/filter.rst:1053: (WARNING/2) Inline emphasis
start-string without end-string.

> Except ``BPF_ADD`` _without_ ``BPF_FETCH`` (for legacy reasons), all 4 byte
> atomic operations require alu32 mode. Clang enables this mode by default in
> architecture v3 (``-mcpu=v3``). For older versions it can be enabled with
> ``-Xclang -target-feature -Xclang +alu32``.

It reads confusing to me.
I would rephrase 'clang enables this mode by default' into
'clang can generate new atomic instruction when -mcpu=v3 is enabled'.

'For older versions...'
This part I didn't get. The users need clang 12 that is capable to
emit these insns.
What 'older versions' you're talking about?

      parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-14 18:17 Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 01/11] bpf: x86: Factor out emission of ModR/M for *(reg + off) Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 02/11] bpf: x86: Factor out emission of REX byte Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 03/11] bpf: x86: Factor out a lookup table for some ALU opcodes Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 04/11] bpf: Rename BPF_XADD and prepare to encode other atomics in .imm Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 05/11] bpf: Move BPF_STX reserved field check into BPF_STX verifier code Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 06/11] bpf: Add BPF_FETCH field / create atomic_fetch_add instruction Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 07/11] bpf: Add instructions for atomic_[cmp]xchg Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 08/11] bpf: Pull out a macro for interpreting atomic ALU operations Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 09/11] bpf: Add bitwise atomic instructions Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 10/11] bpf: Add tests for new BPF atomic operations Brendan Jackman
2021-01-14 18:17 ` [PATCH bpf-next v7 11/11] bpf: Document new atomic instructions Brendan Jackman
2021-01-15  3:20 ` [PATCH bpf-next v7 00/11] Atomics for eBPF patchwork-bot+netdevbpf
2021-01-15  3:23 ` Alexei Starovoitov [this message]

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