control what kernel modules get loaded into ramdisk

control what kernel modules get loaded into ramdisk

[Dan Horák]

Hello,

I started to use dracut for preparing generic ramdisk for Fedora/ARM.
The issue with ramdisks on ARM is that they are usually limited in size
because they are stored in the internal flash memories whose capacity
can be 8 or 16 MB (for kernel, ramdisk and other stuff) in the
commercial devices (like NAS from QNAP). So I used the
"omit_dracutmodules" option in the config file to drop stuff like i18n,
plymouth etc. It works, the created ramdisk is usable, but what remains
quite large are the kernel modules for all filesystems. The ability to
limit the list of drivers for block devices would be also nice. Is there
a way to control what kernel modules get loaded into the ramdisk, like
some black- or whitelist?


Thanks

Dan

[PATCH] Re: control what kernel modules get loaded into ramdisk

[Dan Horák]

[-- Attachment #1: Type: text/plain, Size: 1055 bytes --]

Dan Horák píše v Po 02. 11. 2009 v 18:34 +0100: 
> Hello,
> 
> I started to use dracut for preparing generic ramdisk for Fedora/ARM.
> The issue with ramdisks on ARM is that they are usually limited in size
> because they are stored in the internal flash memories whose capacity
> can be 8 or 16 MB (for kernel, ramdisk and other stuff) in the
> commercial devices (like NAS from QNAP). So I used the
> "omit_dracutmodules" option in the config file to drop stuff like i18n,
> plymouth etc. It works, the created ramdisk is usable, but what remains
> quite large are the kernel modules for all filesystems. The ability to

I have solved the problem with filesystem modules with an introduction
of new command line/config file parameter. It controls the list of
filesystem modules that will be included when running in generic mode.
See the attached patch for details.

> limit the list of drivers for block devices would be also nice. Is there
> a way to control what kernel modules get loaded into the ramdisk, like
> some black- or whitelist?


Dan


[-- Attachment #2: filesystems.patch --]
[-- Type: text/x-patch, Size: 5638 bytes --]

From c903db8863923a6f9d32f6ac5e5481b74cb1e75c Mon Sep 17 00:00:00 2001
From: =?utf-8?q?Dan=20Hor=C3=A1k?= <dan-mBPqX7VnFd4@public.gmane.org>
Date: Tue, 3 Nov 2009 10:39:59 +0100
Subject: [PATCH 1/3] specify a list of kernel filesystem modules to be exlusively included in the initramfs
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit


Signed-off-by: Dan Horák <dan-mBPqX7VnFd4@public.gmane.org>
---
 dracut                                   |    6 +++++-
 dracut.8                                 |    3 +++
 modules.d/90kernel-modules/installkernel |    8 ++++++--
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/dracut b/dracut
index 7b9304f..dbc5d73 100755
--- a/dracut
+++ b/dracut
@@ -37,6 +37,8 @@ Creates initial ramdisk images for preloading modules
                         exclusively include in the initramfs.
   --add-drivers [LIST]  Specify a space-separated list of kernel 
                         modules to add to the initramfs.
+  --filesystems [LIST]  Specify a space-separated list of filesystem kenrel
+                        modules to exclusively include in the initramfs.
   -k, --kmoddir [DIR]   Specify the directory, where to look for kernel 
                         modules
   --fwdir [DIR]         Specify additional directories, where to look for 
@@ -76,6 +78,7 @@ while (($# > 0)); do
 	-a|--add) add_dracutmodules_l="$2"; shift;;
 	-d|--drivers) drivers_l="$2"; shift;;
 	--add-drivers) add_drivers_l="$2"; shift;;
+	--filesystems) filesystems_l="$2"; shift;;
 	-k|--kmoddir) drivers_dir_l="$2"; shift;;
 	--fwdir) fw_dir_l="$2"; shift;;
 	--kernel-only) kernel_only="yes"; nokernel="no";;
@@ -127,6 +130,7 @@ fi
 [[ $add_dracutmodules_l ]] && add_dracutmodules="$add_dracutmodules $add_dracutmodules_l"
 [[ $drivers_l ]] && drivers=$drivers_l
 [[ $add_drivers_l ]] && add_drivers=$add_drivers_l
+[[ $filesystems_l ]] && filesystems=$filesystems_l
 [[ $drivers_dir_l ]] && drivers_dir=$drivers_dir_l
 [[ $fw_dir_l ]] && fw_dir=$fw_dir_l
 [[ $do_strip_l ]] && do_strip=$do_strip_l
@@ -180,7 +184,7 @@ chmod 755 "$initdir"
 
 export initdir hookdirs dracutbasedir dracutmodules drivers \
     fw_dir drivers_dir debug beverbose no_kernel kernel_only \
-    add_drivers mdadmconf lvmconf
+    add_drivers mdadmconf lvmconf filesystems
 
 if [[ $kernel_only != yes ]]; then
     # Create some directory structure first
diff --git a/dracut.8 b/dracut.8
index 309d0dd..93dafc9 100644
--- a/dracut.8
+++ b/dracut.8
@@ -32,6 +32,9 @@ specify a space-separated list of kernel modules to exclusively include in the i
 .BR \-\-add-drivers " \fILIST\fR"
 specify a space-separated list of kernel modules to add to the initramfs.
 .TP
+.BR \-\-filesystems " \fILIST\fR"
+specify a space-separated list of kernel filesystem modules to exclusively include in the initramfs.
+.TP
 .BR \-k ", " \-\-kmoddir " \fI{DIR}\fR   
 specify the directory, where to look for kernel modules
 .TP
diff --git a/modules.d/90kernel-modules/installkernel b/modules.d/90kernel-modules/installkernel
index b5e4c93..77fbe09 100755
--- a/modules.d/90kernel-modules/installkernel
+++ b/modules.d/90kernel-modules/installkernel
@@ -6,9 +6,13 @@ if [[ -z $drivers ]]; then
 	 nm -uPA "$1" | egrep -q "$blockfuncs"
     }
     instmods pcmcia sd_mod $(filter_kernel_modules block_module_test) "=drivers/pcmcia" =ide
-    # if not on hostonly mode, install all known filesystems.
+    # if not on hostonly mode, install all known filesystems if the required list is not set via the filesystems variable
     if [[ $hostonly = '' ]]; then
-	instmods '=fs'
+	if [[ -z $filesystems ]]; then
+	    instmods '=fs'
+	else
+	    instmods $filesystems
+	fi
     else
 	instmods $(get_fs_type "/dev/block/$(find_root_block_device)")
     fi
-- 
1.6.3.3

From d9912f909196d7d53981720b444d1aa23d1edbe6 Mon Sep 17 00:00:00 2001
From: =?utf-8?q?Dan=20Hor=C3=A1k?= <dan-mBPqX7VnFd4@public.gmane.org>
Date: Tue, 3 Nov 2009 11:05:12 +0100
Subject: [PATCH 2/3] add the "filesystems" option into config file
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit


Signed-off-by: Dan Horák <dan-mBPqX7VnFd4@public.gmane.org>
---
 dracut.conf |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/dracut.conf b/dracut.conf
index 2ebeeda..44cecaf 100644
--- a/dracut.conf
+++ b/dracut.conf
@@ -9,6 +9,9 @@
 # additional kernel modules to the default
 #add_drivers=""
 
+# list of kernel filesystem modules to be loaded into generic initramfs
+#filesystems=""
+
 # build initrd only to boot current hardware
 #hostonly="-h"
 #
-- 
1.6.3.3

From 80fe42e3224d4240319ddf56ea3deb807ab1e9aa Mon Sep 17 00:00:00 2001
From: =?utf-8?q?Dan=20Hor=C3=A1k?= <dan-mBPqX7VnFd4@public.gmane.org>
Date: Tue, 3 Nov 2009 11:06:38 +0100
Subject: [PATCH 3/3] append the filesystems list to the exclusive list of kernel modules
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit


Signed-off-by: Dan Horák <dan-mBPqX7VnFd4@public.gmane.org>
---
 modules.d/90kernel-modules/installkernel |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/modules.d/90kernel-modules/installkernel b/modules.d/90kernel-modules/installkernel
index 77fbe09..c739bfc 100755
--- a/modules.d/90kernel-modules/installkernel
+++ b/modules.d/90kernel-modules/installkernel
@@ -19,7 +19,7 @@ if [[ -z $drivers ]]; then
     # hardcoded list of exceptions
     rm -fr ${initdir}/lib/modules/*/kernel/fs/ocfs2
 else
-  instmods $drivers
+  instmods $drivers $filesystems
 fi
 
 [[ $add_drivers ]] && instmods $add_drivers
-- 
1.6.3.3

Re: [PATCH] Re: control what kernel modules get loaded into ramdisk

[Harald Hoyer]

On 11/03/2009 11:25 AM, Dan Horák wrote:
> Dan Horák píše v Po 02. 11. 2009 v 18:34 +0100:
>> Hello,
>>
>> I started to use dracut for preparing generic ramdisk for Fedora/ARM.
>> The issue with ramdisks on ARM is that they are usually limited in size
>> because they are stored in the internal flash memories whose capacity
>> can be 8 or 16 MB (for kernel, ramdisk and other stuff) in the
>> commercial devices (like NAS from QNAP). So I used the
>> "omit_dracutmodules" option in the config file to drop stuff like i18n,
>> plymouth etc. It works, the created ramdisk is usable, but what remains
>> quite large are the kernel modules for all filesystems. The ability to
>
> I have solved the problem with filesystem modules with an introduction
> of new command line/config file parameter. It controls the list of
> filesystem modules that will be included when running in generic mode.
> See the attached patch for details.
>
>> limit the list of drivers for block devices would be also nice. Is there
>> a way to control what kernel modules get loaded into the ramdisk, like
>> some black- or whitelist?
>
>
> Dan
>

s/kenrel/kernel/

s/modules to be loaded into generic initramfs/modules to be included in the 
generic initramfs/

Re: [PATCH] Re: control what kernel modules get loaded into ramdisk

[Dan Horák]

[-- Attachment #1: Type: text/plain, Size: 715 bytes --]

Harald Hoyer píše v Út 03. 11. 2009 v 11:30 +0100: 
> > I have solved the problem with filesystem modules with an introduction
> > of new command line/config file parameter. It controls the list of
> > filesystem modules that will be included when running in generic mode.
> > See the attached patch for details.
> >
> >> limit the list of drivers for block devices would be also nice. Is there
> >> a way to control what kernel modules get loaded into the ramdisk, like
> >> some black- or whitelist?
> >
> >
> > Dan
> >
> 
> s/kenrel/kernel/
> 
> s/modules to be loaded into generic initramfs/modules to be included in the 
> generic initramfs/

updated and joined into 1 commit with better description


Dan


[-- Attachment #2: filesystems.patch --]
[-- Type: text/x-patch, Size: 4576 bytes --]

From e67c382bd883ef6b567933b4800c135fd62c8244 Mon Sep 17 00:00:00 2001
From: =?utf-8?q?Dan=20Hor=C3=A1k?= <dan-mBPqX7VnFd4@public.gmane.org>
Date: Tue, 3 Nov 2009 11:50:55 +0100
Subject: [PATCH] control filesystems included in the generic initramfs
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit

New "filesystems" command line/config file option is added with the ability to
control the list of kernel filesystem modules that are included in the generic
initramfs.

Signed-off-by: Dan Horák <dan-mBPqX7VnFd4@public.gmane.org>
---
 dracut                                   |    7 ++++++-
 dracut.8                                 |    3 +++
 dracut.conf                              |    3 +++
 modules.d/90kernel-modules/installkernel |   10 +++++++---
 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/dracut b/dracut
index 7b9304f..1954177 100755
--- a/dracut
+++ b/dracut
@@ -37,6 +37,9 @@ Creates initial ramdisk images for preloading modules
                         exclusively include in the initramfs.
   --add-drivers [LIST]  Specify a space-separated list of kernel 
                         modules to add to the initramfs.
+  --filesystems [LIST]  Specify a space-separated list of kernel filesystem
+                        modules to exclusively include in the generic
+                        initramfs.
   -k, --kmoddir [DIR]   Specify the directory, where to look for kernel 
                         modules
   --fwdir [DIR]         Specify additional directories, where to look for 
@@ -76,6 +79,7 @@ while (($# > 0)); do
 	-a|--add) add_dracutmodules_l="$2"; shift;;
 	-d|--drivers) drivers_l="$2"; shift;;
 	--add-drivers) add_drivers_l="$2"; shift;;
+	--filesystems) filesystems_l="$2"; shift;;
 	-k|--kmoddir) drivers_dir_l="$2"; shift;;
 	--fwdir) fw_dir_l="$2"; shift;;
 	--kernel-only) kernel_only="yes"; nokernel="no";;
@@ -127,6 +131,7 @@ fi
 [[ $add_dracutmodules_l ]] && add_dracutmodules="$add_dracutmodules $add_dracutmodules_l"
 [[ $drivers_l ]] && drivers=$drivers_l
 [[ $add_drivers_l ]] && add_drivers=$add_drivers_l
+[[ $filesystems_l ]] && filesystems=$filesystems_l
 [[ $drivers_dir_l ]] && drivers_dir=$drivers_dir_l
 [[ $fw_dir_l ]] && fw_dir=$fw_dir_l
 [[ $do_strip_l ]] && do_strip=$do_strip_l
@@ -180,7 +185,7 @@ chmod 755 "$initdir"
 
 export initdir hookdirs dracutbasedir dracutmodules drivers \
     fw_dir drivers_dir debug beverbose no_kernel kernel_only \
-    add_drivers mdadmconf lvmconf
+    add_drivers mdadmconf lvmconf filesystems
 
 if [[ $kernel_only != yes ]]; then
     # Create some directory structure first
diff --git a/dracut.8 b/dracut.8
index 309d0dd..6dc90ad 100644
--- a/dracut.8
+++ b/dracut.8
@@ -32,6 +32,9 @@ specify a space-separated list of kernel modules to exclusively include in the i
 .BR \-\-add-drivers " \fILIST\fR"
 specify a space-separated list of kernel modules to add to the initramfs.
 .TP
+.BR \-\-filesystems " \fILIST\fR"
+specify a space-separated list of kernel filesystem modules to exclusively include in the generic initramfs.
+.TP
 .BR \-k ", " \-\-kmoddir " \fI{DIR}\fR   
 specify the directory, where to look for kernel modules
 .TP
diff --git a/dracut.conf b/dracut.conf
index 2ebeeda..8c8db21 100644
--- a/dracut.conf
+++ b/dracut.conf
@@ -9,6 +9,9 @@
 # additional kernel modules to the default
 #add_drivers=""
 
+# list of kernel filesystem modules to be included in the generic initramfs
+#filesystems=""
+
 # build initrd only to boot current hardware
 #hostonly="-h"
 #
diff --git a/modules.d/90kernel-modules/installkernel b/modules.d/90kernel-modules/installkernel
index b5e4c93..c739bfc 100755
--- a/modules.d/90kernel-modules/installkernel
+++ b/modules.d/90kernel-modules/installkernel
@@ -6,16 +6,20 @@ if [[ -z $drivers ]]; then
 	 nm -uPA "$1" | egrep -q "$blockfuncs"
     }
     instmods pcmcia sd_mod $(filter_kernel_modules block_module_test) "=drivers/pcmcia" =ide
-    # if not on hostonly mode, install all known filesystems.
+    # if not on hostonly mode, install all known filesystems if the required list is not set via the filesystems variable
     if [[ $hostonly = '' ]]; then
-	instmods '=fs'
+	if [[ -z $filesystems ]]; then
+	    instmods '=fs'
+	else
+	    instmods $filesystems
+	fi
     else
 	instmods $(get_fs_type "/dev/block/$(find_root_block_device)")
     fi
     # hardcoded list of exceptions
     rm -fr ${initdir}/lib/modules/*/kernel/fs/ocfs2
 else
-  instmods $drivers
+  instmods $drivers $filesystems
 fi
 
 [[ $add_drivers ]] && instmods $add_drivers
-- 
1.6.3.3