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Date:   Wed, 2 Feb 2022 10:10:47 -0800
From:   Daniel Xu <dxu@dxuuu.xyz>
To:     Luis Chamberlain <mcgrof@kernel.org>
Cc:     Nick Alcock <nick.alcock@oracle.com>, bas smit <bas@baslab.org>,
        =?utf-8?B?VG9tw6HFoQ==?= Glozar <tglozar@gmail.com>,
        Ast-x64 <Ast-x64@protonmail.com>,
        Viktor Malik <viktor.malik@gmail.com>,
        Jiri Olsa <jolsa@kernel.org>, jeyu@kernel.org,
        masahiroy@kernel.org, linux-modules@vger.kernel.org,
        linux-kernel@vger.kernel.org, arnd@arndb.de,
        akpm@linux-foundation.org, eugene.loh@oracle.com,
        kris.van.hees@oracle.com
Subject: Re: [PING PATCH v7] kallsyms: new /proc/kallmodsyms with builtin
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Hi Luis, Nick,

On Tue, Feb 01, 2022 at 07:09:23PM -0800, Luis Chamberlain wrote:
[...]
> 
> I don't see much traction based on what you have said on dtrace
> on anything other than Oracle Linux stuff, it would be nice if bpftrace
> folks were excited about your changes and we had support for that
> there.

I took a quick look at the v7 cover letter (I'll take a look at
discussion from previous versions later if I get time) and it's not
immediately obvious to me why a stable mapping is beneficial.

Nick, could you elaborate why it's beneficial for dtrace to have a
stable mapping?

For what it's worth, bpftrace uses /proc/kallsyms rather rarely.
bpftrace relies on perf_event_open()'s config1 parameter to resolve
kernel symbol name to address for kprobe attachment. /proc/kallsyms is
mostly used to resolve kaddr() calls in bpftrace scripts.

Kernel symbol size information would be useful, though. bpftrace
currently uses the vmlinux ELF to acquire that information.

[...]

Thanks,
Daniel