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Subject: Re: [PATCH v3] streamline_config.pl: add LMC_KEEP to preserve some
 kconfigs
To:     Changbin Du <changbin.du@gmail.com>,
        Masahiro Yamada <masahiroy@kernel.org>
Cc:     Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org,
        Steven Rostedt <rostedt@goodmis.org>,
        linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org
References: <20200502153052.5461-1-changbin.du@gmail.com>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <6a0c13c6-148d-74b3-4ddc-7252b8b112bf@infradead.org>
Date:   Sat, 2 May 2020 08:50:22 -0700
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On 5/2/20 8:30 AM, Changbin Du 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>
> 
> ---
> v3: rename LOCALMODCONFIG_PRESERVE to shorter LMC_KEEP.
> v2: fix typo in documentation. (Randy Dunlap)
> ---
>  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..f7b02ce61ea7 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 spcifying their paths in

                                                  specifying

More below.


> +                           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" \
> +                           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..f3a2ceed1e82 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 @presevered_kconfigs;

s/presevered/preserved/g  (g means globally, throughout this script)

> +@presevered_kconfigs = split(/;/,$ENV{LMC_KEEP}) if (defined($ENV{LMC_KEEP}));
> +
> +sub in_presevered_kconfigs {
> +    my $kconfig = $config2kfile{$_[0]};
> +    if (!defined($kconfig)) {
> +        return 0;
> +    }
> +    foreach my $excl (@presevered_kconfigs) {
> +        if($kconfig =~ /^$excl/) {
> +            return 1;
> +        }
> +    }
> +    return 0;
> +}
> +
>  # Finally, read the .config file and turn off any module enabled that
>  # we could not find a reason to keep enabled.
>  foreach my $line (@config_file) {
> @@ -644,6 +662,11 @@ foreach my $line (@config_file) {
>      }
>  
>      if (/^(CONFIG.*)=(m|y)/) {
> +        if (in_presevered_kconfigs($1)) {
> +            dprint "Preserve config $1";
> +            print;
> +            next;
> +        }
>  	if (defined($configs{$1})) {
>  	    if ($localyesconfig) {
>  	        $setconfigs{$1} = 'y';
> 

thanks.
-- 
~Randy