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Date:   Thu, 7 May 2020 09:18:07 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     Changbin Du <changbin.du@gmail.com>,
        Jonathan Corbet <corbet@lwn.net>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Randy Dunlap <rdunlap@infradead.org>
Subject: Re: [PATCH v4] streamline_config.pl: add LMC_KEEP to preserve some
 kconfigs
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        <CAK7LNATBt1NxRSWiv8Ab-pKBRemp43WUs96KWELTf+vFq_VPTA@mail.gmail.com>
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On Thu, 7 May 2020 12:19:57 +0900
Masahiro Yamada <masahiroy@kernel.org> wrote:

> On Sun, May 3, 2020 at 9:11 AM Changbin Du <changbin.du@gmail.com> wrote:
> >
> > Sometimes it is useful to preserve batches of configs when making
> > localmodconfig. For example, I usually don't want any usb and fs
> > modules to be disabled. Now we can do it by:
> >
> >  $ make LMC_KEEP="drivers/usb;fs" localmodconfig
> >
> > Signed-off-by: Changbin Du <changbin.du@gmail.com>
> >
> > ---
> > v4: fix typo.
> > v3: rename LOCALMODCONFIG_PRESERVE to shorter LMC_KEEP.
> > v2: fix typo in documentation. (Randy Dunlap)
> > ---  
> 
> 
> Personally, I do not mind the long LOCALMODCONFIG_PRESERVE,

Perhasp we allow both? ;-)

And just have one set to the other.

> but this tends to be bike-sheding.
> I do not have a strong opinion.
> 
> 
> >  Documentation/admin-guide/README.rst |  8 +++++++-
> >  scripts/kconfig/Makefile             |  1 +
> >  scripts/kconfig/streamline_config.pl | 23 +++++++++++++++++++++++
> >  3 files changed, 31 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/admin-guide/README.rst b/Documentation/admin-guide/README.rst
> > index cc6151fc0845..1371deab8bc7 100644
> > --- a/Documentation/admin-guide/README.rst
> > +++ b/Documentation/admin-guide/README.rst
> > @@ -209,10 +209,16 @@ Configuring the kernel
> >                             store the lsmod of that machine into a file
> >                             and pass it in as a LSMOD parameter.
> >
> > +                           Also, you can preserve modules in certain folders
> > +                           or kconfig files by specifying their paths in
> > +                           parameter LMC_KEEP.
> > +
> >                     target$ lsmod > /tmp/mylsmod
> >                     target$ scp /tmp/mylsmod host:/tmp
> >
> > -                   host$ make LSMOD=/tmp/mylsmod localmodconfig
> > +                   host$ make LSMOD=/tmp/mylsmod \
> > +                           LMC_KEEP="drivers/usb;drivers/gpu;fs" \  
> 
> 
> This might be another bike-sheding item, but
> can you use a space for the delimiter?
> 
> 
> LMC_KEEP="drivers/usb drivers/gpu fs"
> 
> If you pass multiple directories,
> you will need to surround them with double-quotes.

I agree that spaces look better.

> 
> 
> 
> 
> > +                           localmodconfig
> >
> >                             The above also works when cross compiling.
> >
> > diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
> > index c9d0a4a8efb3..e0abbf5805f5 100644
> > --- a/scripts/kconfig/Makefile
> > +++ b/scripts/kconfig/Makefile
> > @@ -123,6 +123,7 @@ help:
> >         @echo  '  gconfig         - Update current config utilising a GTK+ based front-end'
> >         @echo  '  oldconfig       - Update current config utilising a provided .config as base'
> >         @echo  '  localmodconfig  - Update current config disabling modules not loaded'
> > +       @echo  '                    except those preserved by LMC_KEEP environment variable'
> >         @echo  '  localyesconfig  - Update current config converting local mods to core'
> >         @echo  '  defconfig       - New config with default from ARCH supplied defconfig'
> >         @echo  '  savedefconfig   - Save current config as ./defconfig (minimal config)'
> > diff --git a/scripts/kconfig/streamline_config.pl b/scripts/kconfig/streamline_config.pl
> > index e2f8504f5a2d..d26543a807c9 100755
> > --- a/scripts/kconfig/streamline_config.pl
> > +++ b/scripts/kconfig/streamline_config.pl
> > @@ -143,6 +143,7 @@ my %depends;
> >  my %selects;
> >  my %prompts;
> >  my %objects;
> > +my %config2kfile;
> >  my $var;
> >  my $iflevel = 0;
> >  my @ifdeps;
> > @@ -201,6 +202,7 @@ sub read_kconfig {
> >         if (/^\s*(menu)?config\s+(\S+)\s*$/) {
> >             $state = "NEW";
> >             $config = $2;
> > +           $config2kfile{"CONFIG_$config"} = $kconfig;
> >
> >             # Add depends for 'if' nesting
> >             for (my $i = 0; $i < $iflevel; $i++) {
> > @@ -592,6 +594,22 @@ while ($repeat) {
> >
> >  my %setconfigs;
> >
> > +my @preserved_kconfigs;
> > +@preserved_kconfigs = split(/;/,$ENV{LMC_KEEP}) if (defined($ENV{LMC_KEEP}));  
> 
> Maybe, you can do 'my' declaration and the assignment
> in a single line?
> 
> Can you drop the 'if ...' conditional?
> 
> 
> Does this work for you?
> 
> my @preserved_kconfigs = split(/;/,$ENV{LMC_KEEP});
> 
> 

Will an undefined warning happen if LMC_KEEP isn't defined?

-- Steve