From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Marek Subject: Re: [PATCH v2 1/2] scripts: Add a recorduidiv program Date: Mon, 30 Nov 2015 16:11:16 +0100 Message-ID: <565C6714.802@suse.com> References: <1448488264-23400-1-git-send-email-sboyd@codeaurora.org> <1448488264-23400-2-git-send-email-sboyd@codeaurora.org> <20151125234711.GT8644@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20151125234711.GT8644@n2100.arm.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org To: Russell King - ARM Linux Cc: Stephen Boyd , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, Thomas Petazzoni , linux-kbuild@vger.kernel.org, Nicolas Pitre , Arnd Bergmann , Steven Rostedt , =?UTF-8?B?TcOlbnMgUnVsbGfDpXJk?= List-Id: linux-arm-msm@vger.kernel.org On 2015-11-26 00:47, Russell King - ARM Linux wrote: > On Wed, Nov 25, 2015 at 01:51:03PM -0800, Stephen Boyd wrote: >> The ARM compiler inserts calls to __aeabi_uidiv() and >> __aeabi_idiv() when it needs to perform division on signed and >> unsigned integers. If a processor has support for the udiv and >> sdiv division instructions the calls to these support routines >> can be replaced with those instructions. Therefore, record the >> location of calls to these library functions into two sections >> (one for udiv and one for sdiv) similar to how we trace calls to >> mcount. When the kernel boots up it will check to see if the >> processor supports the instructions and then patch the call sites >> with the instruction. > > Do we have any resolution on these programs which modify the object > files in-place, rather than breaking any hard-links which may be > present (eg, as a result of using ccache in hard-link mode) ? Good point, but I do not think anybody is using CCACHE_HARDLINK with the kernel. As the manpage says, it is going to confuse make, so the time saved by ccache would be offset by make trying to recompile all *.c files each time. Michal