From: Nicolas Boichat <drinkcat@chromium.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Douglas Anderson <dianders@chromium.org>,
Guenter Roeck <groeck@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
"Guilherme G. Piccoli" <gpiccoli@canonical.com>,
Kars Mulder <kerneldev@karsmulder.nl>,
Kees Cook <keescook@chromium.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
Thomas Gleixner <tglx@linutronix.de>,
Tiezhu Yang <yangtiezhu@loongson.cn>,
Will Deacon <will@kernel.org>, Yue Hu <huyue2@yulong.com>,
linux-kbuild@vger.kernel.org, lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5] kernel/trace: Add DISALLOW_TRACE_PRINTK make option
Date: Tue, 25 Aug 2020 08:38:27 +0800 [thread overview]
Message-ID: <CANMq1KCQjX1632qyo5+8kv8TXNu_Onh4gz7oMx3rx79XQX2fqg@mail.gmail.com> (raw)
In-Reply-To: <20200824093020.073ae8d8@oasis.local.home>
On Mon, Aug 24, 2020 at 9:30 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Mon, 24 Aug 2020 10:59:13 +0800
> Nicolas Boichat <drinkcat@chromium.org> wrote:
>
> > ---
> >
> > +ifeq ($(KBUILD_DISALLOW_TRACE_PRINTK),1)
> > +KBUILD_CFLAGS += -DDISALLOW_TRACE_PRINTK
> > +endif
> > +
> > KBUILD_CFLAGS += $(DEBUG_CFLAGS)
> > export DEBUG_CFLAGS
> >
>
>
> There's one more thing we need to do, is if you build without this option
> then build with it, you should trigger a full kernel rebuild.
> Otherwise, if you build without the option, then build with it, and it
> doesn't rebuild the tree, it wont catch anything.
This already works. I'll be honest, I'm not 100% sure why (and if
fully intentional)...
The CFLAGS end up in 3 generated assembly files:
# grep -R DISALLOW_TRACE_PRINTK * | grep -v ".cmd:"
arch/x86/kernel/asm-offsets.s:# -imultiarch x86_64-linux-gnu -D
__KERNEL__ -D DISALLOW_TRACE_PRINTK
kernel/bounds.s:# -imultiarch x86_64-linux-gnu -D __KERNEL__ -D
DISALLOW_TRACE_PRINTK
scripts/mod/devicetable-offsets.s:# -D DISALLOW_TRACE_PRINTK
(along with all *.cmd files)
and I suspect some/all of those force a complete kernel rebuild.
> -- Steve
next prev parent reply other threads:[~2020-08-25 0:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-24 2:59 [PATCH v5] kernel/trace: Add DISALLOW_TRACE_PRINTK make option Nicolas Boichat
2020-08-24 8:26 ` David Laight
2020-08-24 13:28 ` Steven Rostedt
2020-08-24 13:42 ` Andy Shevchenko
2020-08-24 18:26 ` Steven Rostedt
2020-08-24 13:30 ` Steven Rostedt
2020-08-25 0:38 ` Nicolas Boichat [this message]
2020-08-26 1:39 ` Steven Rostedt
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