Hi Sam, On Fri, May 10, 2019 at 9:03 AM Sam Ravnborg <sam@xxxxxxxxxxxx> wrote: > On Fri, May 10, 2019 at 08:46:35AM +0200, Geert Uytterhoeven wrote: > > On Fri, May 10, 2019 at 8:14 AM Masahiro Yamada > > <yamada.masahiro@xxxxxxxxxxxxx> wrote: > > > Kconfig updates the .config when it exits even if its content is > > > exactly the same as before. Since its timestamp becomes newer than > > > that of other build artifacts, additional processing is invoked, > > > which is annoying. > > > > > > - syncconfig is invoked to update include/config/auto.conf, etc. > > > > > > - kernel/config.o is recompiled if CONFIG_IKCONFIG is enabled, > > > then vmlinux is relinked as well. > > > > > > If the .config is not changed at all, we do not have to even > > > touch it. Just bail out showing "No change to .config". > > This causes a semantic change for the meaning of ".config.old", which is > > no longer updated if .config has not changed. > > Hence its contents may no longer correspond to the previous config, but to > > an arbitrary older version. > This semantic change is good. > So we now have a .config.old that correspond to the state before > the last change. Also after several kernel builds. > > > > My workflow involves always running my own script "linux-oldconfig", > > instead of "make oldconfig", so I immediately see what has changed: > > > > $ cat $(type -p linux-oldconfig) > > #!/bin/bash > > make ${0#*/linux-} && colordiff -u .config{.old,} > So scripts relying on the old (broken) behaviour will no longer work. > The new behaviour is better as it is usefaul in many typical situations. > > Hacking, hack. What did I change in the config? I agree both semantics have their merits. Sometimes I also wanted to see the last real change... No worries, updating my script, so it works with both semantics: $ cat $(type -p linux-oldconfig) #!/bin/bash cp -a .config .config.orig make ${0#*/linux-} && colordiff -u .config{.orig,} Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds