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From: Steven Rostedt <>
To: Masahiro Yamada <>
Cc: Nicolas Boichat <>,,,
	Andrew Morton <>,
	Andy Shevchenko <>,
	"Guilherme G. Piccoli" <>,
	Kars Mulder <>,
	Kees Cook <>,
	Michal Marek <>,
	Rafael Aquini <>,
	Thomas Gleixner <>,
	Will Deacon <>,,
Subject: Re: [PATCH v6] kernel/trace: Add DISALLOW_TRACE_PRINTK make option
Date: Mon, 28 Sep 2020 11:26:46 -0400	[thread overview]
Message-ID: <20200928112646.4968999c@oasis.local.home> (raw)
In-Reply-To: <20200928152840.v6.1.I4feb11d34ce7a0dd5ee2c3327fb5a1a9a646be30@changeid>

On Mon, 28 Sep 2020 15:29:29 +0800
Nicolas Boichat <> wrote:

> trace_printk is meant as a debugging tool, and should not be
> compiled into production code without specific debug Kconfig
> options enabled, or source code changes, as indicated by the
> warning that shows up on boot if any trace_printk is called:
>  **                                                      **
>  ** trace_printk() being used. Allocating extra memory.  **
>  **                                                      **
>  ** This means that this is a DEBUG kernel and it is     **
>  ** unsafe for production use.                           **
> If DISALLOW_TRACE_PRINTK=1 is passed on the make command
> line, the kernel will generate a build-time error if
> trace_printk is used. We expect distributors to set this
> option for their production kernels.
> Note that the code to handle trace_printk is still present,
> so this does not prevent people from compiling out-of-tree
> kernel modules, or BPF programs.
> Also, we are not making this a kernel config option as we
> want the developer convenience of being able to reuse a
> production kernel config, add trace_printk for debugging,
> and rebuild, without any config changes.
> Signed-off-by: Nicolas Boichat <>


Are you OK with this change? If so can I have your Ack?

-- Steve

      reply	other threads:[~2020-09-28 15:26 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-28  7:29 [PATCH v6] kernel/trace: Add DISALLOW_TRACE_PRINTK make option Nicolas Boichat
2020-09-28 15:26 ` Steven Rostedt [this message]

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