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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Quentin Monnet <quentin@isovalent.com>
Cc: "Daniel Borkmann" <daniel@iogearbox.net>,
	"Jianlin Lv" <Jianlin.Lv@arm.com>, bpf <bpf@vger.kernel.org>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Alexei Starovoitov" <ast@kernel.org>,
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Subject: Re: [PATCH bpf-next 1/2] bpf: Remove bpf_jit_enable=2 debugging mode
Date: Thu, 15 Apr 2021 16:49:36 -0700
Message-ID: <CAADnVQJ2oHbYfgY9jqM_JMxUsoZxaNrxKSVFYfgCXuHVpDehpQ@mail.gmail.com> (raw)
In-Reply-To: <d3949501-8f7d-57c4-b3fe-bcc3b24c09d8@isovalent.com>

On Thu, Apr 15, 2021 at 8:41 AM Quentin Monnet <quentin@isovalent.com> wrote:
>
> 2021-04-15 16:37 UTC+0200 ~ Daniel Borkmann <daniel@iogearbox.net>
> > On 4/15/21 11:32 AM, Jianlin Lv wrote:
> >> For debugging JITs, dumping the JITed image to kernel log is discouraged,
> >> "bpftool prog dump jited" is much better way to examine JITed dumps.
> >> This patch get rid of the code related to bpf_jit_enable=2 mode and
> >> update the proc handler of bpf_jit_enable, also added auxiliary
> >> information to explain how to use bpf_jit_disasm tool after this change.
> >>
> >> Signed-off-by: Jianlin Lv <Jianlin.Lv@arm.com>
>
> Hello,
>
> For what it's worth, I have already seen people dump the JIT image in
> kernel logs in Qemu VMs running with just a busybox, not for kernel
> development, but in a context where buiding/using bpftool was not
> possible.

If building/using bpftool is not possible then majority of selftests won't
be exercised. I don't think such environment is suitable for any kind
of bpf development. Much so for JIT debugging.
While bpf_jit_enable=2 is nothing but the debugging tool for JIT developers.
I'd rather nuke that code instead of carrying it from kernel to kernel.

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Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-15  9:32 Jianlin Lv
2021-04-15  9:32 ` [PATCH bpf-next 2/2] docs: bpf: bpf_jit_enable mode changed Jianlin Lv
2021-04-15 14:37 ` [PATCH bpf-next 1/2] bpf: Remove bpf_jit_enable=2 debugging mode Daniel Borkmann
2021-04-15 15:41   ` Quentin Monnet
2021-04-15 23:49     ` Alexei Starovoitov [this message]
2021-04-17  8:16       ` Christophe Leroy
2021-04-20  3:28         ` Alexei Starovoitov
2021-04-21 13:10           ` Christophe Leroy
2021-04-21 15:27             ` Quentin Monnet
2021-04-21 16:29             ` John Fastabend
2021-04-23  7:19           ` Christophe Leroy
2021-04-23 10:26             ` Quentin Monnet
2021-04-23 10:46               ` Christophe Leroy
2021-04-23 10:59                 ` Quentin Monnet
2021-04-23 11:29                   ` Christophe Leroy
2021-05-14  6:34               ` Christophe Leroy
2021-04-16 13:38   ` Jianlin Lv

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