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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49249238900sm129230375e9.4.2026.06.21.05.55.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 21 Jun 2026 05:55:33 -0700 (PDT) Date: Sun, 21 Jun 2026 13:55:31 +0100 From: David Laight To: Thomas Gleixner Cc: Steven Rostedt , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Linus Torvalds , Sebastian Andrzej Siewior , John Ogness , Peter Zijlstra , Julia Lawall , Yury Norov , linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, dri-devel@lists.freedesktop.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-rdma@vger.kernel.org, linux-usb@vger.kernel.org, linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org, kvm@vger.kernel.org, intel-gfx@lists.freedesktop.org Subject: Re: [PATCH 2/2] tracing: Add CONFIG_TRACE_PRINTK_DEBUGGING to clean up kernel.h Message-ID: <20260621135531.243375d9@pumpkin> In-Reply-To: <87ik7cmcb7.ffs@fw13> References: <20260621093430.264983361@kernel.org> <20260621093811.168514984@kernel.org> <87ik7cmcb7.ffs@fw13> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 21 Jun 2026 12:13:00 +0200 Thomas Gleixner wrote: > On Sun, Jun 21 2026 at 05:34, Steven Rostedt wrote: > > Instead of having trace_printk.h included in kernel.h, create a config > > TRACE_PRINTK_DEBUGGING that when set will update the CFLAGS in the > > Makefile to allow developers to add trace_printk() without the need to add > > the include for it. Having it included in the Makefile keeps it from being > > in the dependency chain and it will not waste extra CPU cycles for those > > building the kernel without using trace_printk. > > IOW, you make it worse just because. > > With the header being separate I add the three trace_printk()s and the > include to the source file I'm investigating. The recompile will build > exactly this source file. > > Having to enable the config knob will result in a full kernel rebuild > for no value. Indeed... Isn't trace_printk() just an extern? Having it defined somewhere isn't going to make any difference to build times. David > > Seriously? > > Thanks, > > tglx > > >