Re: kms in defconfig

Steven Rostedt
2009-04-28T21:23:22Z

On Tue, 28 Apr 2009, Ingo Molnar wrote:
> >
> > My script requires that you have booted the kernel (or similar
> > kernel with the same config options and modules). It then runs
> > lsmod, and searches for the options that enable those modules. It
> > then reads the current .config file and prints out a new config
> > that disables all module configs that are not used to enable the
> > modules found with lsmod.
> >
> > Here's the code (perl script):
> >
> > http://rostedt.homelinux.com/code/streamline_config.pl
> >
> > The instructions on how to use it are at the top of the file.
> >
> > This script has brought down my full kernel compile times with
> > distcc from 50 minutes to under 10.
>
> Looks rather useful IMHO.

There's one little bug. It does not catch configs that are modules that
depend on other configs as modules (but do not have modules mapped).

I can fix this by also scanning the Kconfig* files, and include any
"depends on" as well.

>
> I use the following magic incantation in cfs-debug-info.sh to get to
> the distro config automatically:
>
> KREL=`uname -r | sed 's/smp$//g'`
> ( cat "`rpm -ql kernel-$KREL 2>/dev/null | grep /boot/config`"
> cat "`rpm -ql kernel-smp-$KREL 2>/dev/null | grep /boot/config`"
> cat "`dpkg -L linux-image-$KREL 2>/dev/null | grep /boot/config`"
> cat /boot/config-$KREL 2>/dev/null
> )
>
> Works on most .rpm and .deb based distros. (If /proc/config.gz is
> present that could be added too.)
>
> So if this was added as a 'make builtinconfig' kind of shortcut,
> with no extra steps needed (and if the script bailed out if it
> cannot find the currently booted .config) - that would be a rather
> useful (and easy) way to start kernel development on a new box.
>
> Useful to newbies and oldbies alike IMHO.

Yes, it would be nice to automate this.

-- Steve