On Wed, 10 Dec 2008 21:02:42 +0100 Sam Ravnborg <sam@xxxxxxxxxxxx> wrote: > On Wed, Dec 10, 2008 at 02:48:35PM -0500, Steven Rostedt wrote: > > > > Hi, > > > > In include/linux/kernel.h I currently have the following lines at the > > bottom of the file: > > > > /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */ > > #ifdef CONFIG_FTRACE_MCOUNT_RECORD > > # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD > > #endif > > > > > > This is only there to force a rebuild of all files when > > CONFIG_FTRACE_MCOUNT_RECORD is modified. Since the modification of that > > config causes the build to act different, we need to rebuild all C > > objects. I added the #ifdef in kernel.h as a hack to force the rebuild by > > the config dependencies used in kbuild. > > > > My question is, is there a better way to force a full rebuild on a > > modification of a config? > > Why is that hack required in the first place? > We rebuild if: > - target file is missing (not the case here) > - any prerequisite files are newer than target (not the case here) > - any CONFIG_* options used by any prerequisite has changed (not the case here) > [It is due to your hack] > - gcc changed (not the case here) > - options are added/deleted to gcc (this should be the case for relevant files) > > > Looking a bit deeper into this. > I see that we have in Makefile.build: > > define rule_cc_o_c > $(call echo-cmd,checksrc) $(cmd_checksrc) \ > $(call echo-cmd,cc_o_c) $(cmd_cc_o_c); \ > $(cmd_modversions) \ > $(cmd_record_mcount) > > So you want everyting to be rebuild if the command above changes. > That should be doable - and it is indeed a bug that we do not do so. > The integration of record_mcount needs to be improved. Yes, changing the state of CONFIG_CC_OPTIMIZE_FOR_SIZE does exactly what Steven wants. But damn me it's hard to work out where and how this is implemented :( -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
