From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Luis R. Rodriguez" Subject: Re: [RFC v3 07/13] tables.h: add linker table support Date: Fri, 12 Aug 2016 19:04:52 +0200 Message-ID: <20160812170451.GE3296@wotan.suse.de> References: <1469222687-1600-8-git-send-email-mcgrof@kernel.org> <20160729100630.GA27271@nazgul.tnic> <20160808150539.GG3296@wotan.suse.de> <20160809035508.GC11445@nazgul.tnic> <20160812035129.GA3296@wotan.suse.de> <20160812052303.GB12013@nazgul.tnic> <20160812065011.GB3296@wotan.suse.de> <20160812072507.GC12013@nazgul.tnic> <20160812152805.GD3296@wotan.suse.de> <20160812155121.GB13315@nazgul.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20160812155121.GB13315@nazgul.tnic> Sender: linux-ia64-owner@vger.kernel.org To: Borislav Petkov Cc: "Luis R. Rodriguez" , hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, linux@arm.linux.org.uk, mhiramat@kernel.org, masami.hiramatsu.pt@hitachi.com, jbaron@akamai.com, heiko.carstens@de.ibm.com, ananth@linux.vnet.ibm.com, anil.s.keshavamurthy@intel.com, davem@davemloft.net, realmz6@gmail.com, x86@kernel.org, luto@amacapital.net, keescook@chromium.org, torvalds@linux-foundation.org, gregkh@linuxfoundation.org, rusty@rustcorp.com.au, gnomes@lxorguk.ukuu.org.uk, alan@linux.intel.com, dwmw2@infradead.org, arnd@arndb.de, ming.lei@canonical.com, linux-arch@vger.kernel.org, benh@kernel.crashing.org, ananth@in.ibm.com, pebolle@tiscali.nl, fontana@sharpeleven.org, ciaran.farrell@suse.com, christopher.denicolo@suse.com, david.vrabel@citrix.com, konrad.wilk@oracle.com, mcb30@ipxe.org, jgross@suse.com, andrew.cooper3@citrix.com, andriy.shevchenko@linux.intel List-Id: linux-arch.vger.kernel.org On Fri, Aug 12, 2016 at 05:51:21PM +0200, Borislav Petkov wrote: > On Fri, Aug 12, 2016 at 05:28:05PM +0200, Luis R. Rodriguez wrote: > > Even so, you don't link the compiled extra code so the only penalty > > here is when compiling, nothing more. And if you are compiling typically > > the cost here is just a few seconds. > > Yeah, so let's make it clear that this is similar to COMPILE_TEST and > people with fast machines and who don't mind building a couple more > seconds longer, should enable it. Sure, I'll also move it under COMPILE_TEST, and default it to n. > You don't want to be doing bit-rotting tests on small, weak machines, > which barely get done with the build as it is. I have a 32-bit atom > which takes hours to build a kernel. Enabling that there is not making > the kernel build any more fun. > > > > ... or you simply don't want to have stuff which is forcibly enabled on you even > > > if you're never going to need it > > > ... > > > > Which seems to be the same as the reason I noted ? > > No, the reason is we don't force stuff down people's throats just > because we think we know better. Other people do that. > > Instead, we help them make an informed decision by describing the > feature as precisely as possible. > > > I can remove the grumpy maintainer description :) > > Yap :-) Alright, how's this new description: diff --git a/init/Kconfig b/init/Kconfig index cac3f096050d..73e4890c24c4 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -53,6 +53,34 @@ config CROSS_COMPILE need to set this unless you want the configured kernel build directory to select the cross-compiler automatically. +config BUILD_AVOID_BITROT + bool "Always force building specially annotated targets" + default n + help + If enabled then the the special table-* Makefile targets will always + be forced to be compiled even if their respective CONFIG_ option has + been disabled, but its objects will only be linked in if the same + respective CONFIG_ option has been enabled. This helps avoid code + bit rot issues, use for these targets should be carefully considred + by maintainers. You can safely enable this option at the expense of + increasing compile time. Enabling this option helps avoid code bit + rot by taking advantage of the facilities provided and enabled by + using linker tables documented under: + + include/linux/tables.h + + The special targets supported are: + + o table-obj-y + o table-lib-y + + Say Y if you have a decent build machine and would like to help test + building code for more subsystems. Say N if you do you not have a + good build machine or only want to compile what you've enabled for + your kernel. + + Enabling this option never increases the size of your kernel. + config COMPILE_TEST bool "Compile also drivers which will not load" depends on !UML From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:44738 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932115AbcHLREz (ORCPT ); Fri, 12 Aug 2016 13:04:55 -0400 Date: Fri, 12 Aug 2016 19:04:52 +0200 From: "Luis R. Rodriguez" Subject: Re: [RFC v3 07/13] tables.h: add linker table support Message-ID: <20160812170451.GE3296@wotan.suse.de> References: <1469222687-1600-8-git-send-email-mcgrof@kernel.org> <20160729100630.GA27271@nazgul.tnic> <20160808150539.GG3296@wotan.suse.de> <20160809035508.GC11445@nazgul.tnic> <20160812035129.GA3296@wotan.suse.de> <20160812052303.GB12013@nazgul.tnic> <20160812065011.GB3296@wotan.suse.de> <20160812072507.GC12013@nazgul.tnic> <20160812152805.GD3296@wotan.suse.de> <20160812155121.GB13315@nazgul.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160812155121.GB13315@nazgul.tnic> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Borislav Petkov Cc: "Luis R. Rodriguez" , hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, linux@arm.linux.org.uk, mhiramat@kernel.org, masami.hiramatsu.pt@hitachi.com, jbaron@akamai.com, heiko.carstens@de.ibm.com, ananth@linux.vnet.ibm.com, anil.s.keshavamurthy@intel.com, davem@davemloft.net, realmz6@gmail.com, x86@kernel.org, luto@amacapital.net, keescook@chromium.org, torvalds@linux-foundation.org, gregkh@linuxfoundation.org, rusty@rustcorp.com.au, gnomes@lxorguk.ukuu.org.uk, alan@linux.intel.com, dwmw2@infradead.org, arnd@arndb.de, ming.lei@canonical.com, linux-arch@vger.kernel.org, benh@kernel.crashing.org, ananth@in.ibm.com, pebolle@tiscali.nl, fontana@sharpeleven.org, ciaran.farrell@suse.com, christopher.denicolo@suse.com, david.vrabel@citrix.com, konrad.wilk@oracle.com, mcb30@ipxe.org, jgross@suse.com, andrew.cooper3@citrix.com, andriy.shevchenko@linux.intel.com, paul.gortmaker@windriver.com, xen-devel@lists.xensource.com, ak@linux.intel.com, pali.rohar@gmail.com, dvhart@infradead.org, platform-driver-x86@vger.kernel.org, mmarek@suse.com, linux@rasmusvillemoes.dk, jkosina@suse.cz, korea.drzix@gmail.com, linux-kbuild@vger.kernel.org, tony.luck@intel.com, akpm@linux-foundation.org, linux-ia64@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, catalin.marinas@arm.com, will.deacon@arm.com, rostedt@goodmis.org, jpoimboe@redhat.com Message-ID: <20160812170452.yj6wMi7qD_EgEvTp3POLEPDXlpjCHoKrOAeOVqpT7Fs@z> On Fri, Aug 12, 2016 at 05:51:21PM +0200, Borislav Petkov wrote: > On Fri, Aug 12, 2016 at 05:28:05PM +0200, Luis R. Rodriguez wrote: > > Even so, you don't link the compiled extra code so the only penalty > > here is when compiling, nothing more. And if you are compiling typically > > the cost here is just a few seconds. > > Yeah, so let's make it clear that this is similar to COMPILE_TEST and > people with fast machines and who don't mind building a couple more > seconds longer, should enable it. Sure, I'll also move it under COMPILE_TEST, and default it to n. > You don't want to be doing bit-rotting tests on small, weak machines, > which barely get done with the build as it is. I have a 32-bit atom > which takes hours to build a kernel. Enabling that there is not making > the kernel build any more fun. > > > > ... or you simply don't want to have stuff which is forcibly enabled on you even > > > if you're never going to need it > > > ... > > > > Which seems to be the same as the reason I noted ? > > No, the reason is we don't force stuff down people's throats just > because we think we know better. Other people do that. > > Instead, we help them make an informed decision by describing the > feature as precisely as possible. > > > I can remove the grumpy maintainer description :) > > Yap :-) Alright, how's this new description: diff --git a/init/Kconfig b/init/Kconfig index cac3f096050d..73e4890c24c4 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -53,6 +53,34 @@ config CROSS_COMPILE need to set this unless you want the configured kernel build directory to select the cross-compiler automatically. +config BUILD_AVOID_BITROT + bool "Always force building specially annotated targets" + default n + help + If enabled then the the special table-* Makefile targets will always + be forced to be compiled even if their respective CONFIG_ option has + been disabled, but its objects will only be linked in if the same + respective CONFIG_ option has been enabled. This helps avoid code + bit rot issues, use for these targets should be carefully considred + by maintainers. You can safely enable this option at the expense of + increasing compile time. Enabling this option helps avoid code bit + rot by taking advantage of the facilities provided and enabled by + using linker tables documented under: + + include/linux/tables.h + + The special targets supported are: + + o table-obj-y + o table-lib-y + + Say Y if you have a decent build machine and would like to help test + building code for more subsystems. Say N if you do you not have a + good build machine or only want to compile what you've enabled for + your kernel. + + Enabling this option never increases the size of your kernel. + config COMPILE_TEST bool "Compile also drivers which will not load" depends on !UML