[Buildroot] [PATCH] busybox: provide /etc/mdev.conf if mdev is used

[Buildroot] [PATCH] busybox: provide /etc/mdev.conf if mdev is used

[Luca Ceresoli]

Without an mdev.conf file installed, mdev generates some /dev entries in
an incorrect or non-standard way. Some examples:
 1. /dev/null has permissions 660, but it should be accessible to normal
    users;
 2. alsa devices get created in /dev, not /dev/snd as is more common,
    and as the default value of BR2_PACKAGE_ALSA_LIB_DEVDIR suggests;
 3. event<N> files are created in /dev, not /dev/input.

This mdev.conf is a selection from the examples provided in the busybox
sources with minor tweaks.

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
---
 package/busybox/busybox.mk |    4 ++++
 package/busybox/mdev.conf  |   35 +++++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 0 deletions(-)
 create mode 100644 package/busybox/mdev.conf

diff --git a/package/busybox/busybox.mk b/package/busybox/busybox.mk
index 509c3bb..30b7ab6 100644
--- a/package/busybox/busybox.mk
+++ b/package/busybox/busybox.mk
@@ -33,6 +33,9 @@ ifeq ($(BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_MDEV),y)
 define BUSYBOX_INSTALL_MDEV_SCRIPT
 	install -m 0755 package/busybox/S10mdev $(TARGET_DIR)/etc/init.d
 endef
+define BUSYBOX_INSTALL_MDEV_CONF
+	install -m 0644 package/busybox/mdev.conf $(TARGET_DIR)/etc
+endef
 define BUSYBOX_SET_MDEV
 	$(call KCONFIG_ENABLE_OPT,CONFIG_MDEV,$(BUSYBOX_BUILD_CONFIG))
 	$(call KCONFIG_ENABLE_OPT,CONFIG_FEATURE_MDEV_CONF,$(BUSYBOX_BUILD_CONFIG))
@@ -159,6 +162,7 @@ define BUSYBOX_INSTALL_TARGET_CMDS
 			$(TARGET_DIR)/usr/share/udhcpc/default.script; \
 	fi
 	$(BUSYBOX_INSTALL_MDEV_SCRIPT)
+	$(BUSYBOX_INSTALL_MDEV_CONF)
 	$(BUSYBOX_INSTALL_LOGGING_SCRIPT)
 endef
 
diff --git a/package/busybox/mdev.conf b/package/busybox/mdev.conf
new file mode 100644
index 0000000..247c0ed
--- /dev/null
+++ b/package/busybox/mdev.conf
@@ -0,0 +1,35 @@
+# null may already exist; therefore ownership has to be changed with command
+null		root:root 666 @chmod 666 $MDEV
+zero		root:root 666
+full		root:root 666
+random		root:root 444
+urandom		root:root 444
+hwrandom	root:root 444
+grsec		root:root 660
+
+kmem		root:root 640
+mem		root:root 640
+port		root:root 640
+# console may already exist; therefore ownership has to be changed with command
+console		root:tty 600 @chmod 600 $MDEV
+ptmx		root:tty 666
+pty.*		root:tty 660
+
+# Typical devices
+tty		root:tty 666
+tty[0-9]*	root:tty 660
+vcsa*[0-9]*	root:tty 660
+ttyS[0-9]*	root:root 660
+
+# alsa sound devices
+pcm.*		root:audio 660 =snd/
+control.*	root:audio 660 =snd/
+midi.*		root:audio 660 =snd/
+seq		root:audio 660 =snd/
+timer		root:audio 660 =snd/
+
+# input stuff
+event[0-9]+	root:root 640 =input/
+mice		root:root 640 =input/
+mouse[0-9]	root:root 640 =input/
+ts[0-9]		root:root 600 =input/
-- 
1.7.4.1

[Buildroot] [PATCH] busybox: provide /etc/mdev.conf if mdev is used

[Peter Korsgaard]

>>>>> "Luca" == Luca Ceresoli <luca@lucaceresoli.net> writes:

 Luca> Without an mdev.conf file installed, mdev generates some /dev entries in
 Luca> an incorrect or non-standard way. Some examples:
 Luca>  1. /dev/null has permissions 660, but it should be accessible to normal
 Luca>     users;
 Luca>  2. alsa devices get created in /dev, not /dev/snd as is more common,
 Luca>     and as the default value of BR2_PACKAGE_ALSA_LIB_DEVDIR suggests;
 Luca>  3. event<N> files are created in /dev, not /dev/input.

 Luca> This mdev.conf is a selection from the examples provided in the busybox
 Luca> sources with minor tweaks.

Looks good, except for ..

 Luca> diff --git a/package/busybox/busybox.mk b/package/busybox/busybox.mk
 Luca> index 509c3bb..30b7ab6 100644
 Luca> --- a/package/busybox/busybox.mk
 Luca> +++ b/package/busybox/busybox.mk
 Luca> @@ -33,6 +33,9 @@ ifeq ($(BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_MDEV),y)
 Luca>  define BUSYBOX_INSTALL_MDEV_SCRIPT
 Luca>  	install -m 0755 package/busybox/S10mdev $(TARGET_DIR)/etc/init.d
 Luca>  endef
 Luca> +define BUSYBOX_INSTALL_MDEV_CONF
 Luca> +	install -m 0644 package/busybox/mdev.conf $(TARGET_DIR)/etc

Please use install -D, and only install if the file is not already
there in the rootfs.

Otherwise it looks good. Care to fix and resend?

-- 
Bye, Peter Korsgaard

[Buildroot] [PATCH] busybox: provide /etc/mdev.conf if mdev is used

[Luca Ceresoli]

Il 08/07/2011 20:06, Peter Korsgaard ha scritto:
>>>>>> "Luca" == Luca Ceresoli<luca@lucaceresoli.net>  writes:
>
>   Luca>  Without an mdev.conf file installed, mdev generates some /dev entries in
>   Luca>  an incorrect or non-standard way. Some examples:
>   Luca>   1. /dev/null has permissions 660, but it should be accessible to normal
>   Luca>      users;
>   Luca>   2. alsa devices get created in /dev, not /dev/snd as is more common,
>   Luca>      and as the default value of BR2_PACKAGE_ALSA_LIB_DEVDIR suggests;
>   Luca>   3. event<N>  files are created in /dev, not /dev/input.
>
>   Luca>  This mdev.conf is a selection from the examples provided in the busybox
>   Luca>  sources with minor tweaks.
>
> Looks good, except for ..
>
>   Luca>  diff --git a/package/busybox/busybox.mk b/package/busybox/busybox.mk
>   Luca>  index 509c3bb..30b7ab6 100644
>   Luca>  --- a/package/busybox/busybox.mk
>   Luca>  +++ b/package/busybox/busybox.mk
>   Luca>  @@ -33,6 +33,9 @@ ifeq ($(BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_MDEV),y)
>   Luca>   define BUSYBOX_INSTALL_MDEV_SCRIPT
>   Luca>   	install -m 0755 package/busybox/S10mdev $(TARGET_DIR)/etc/init.d
>   Luca>   endef
>   Luca>  +define BUSYBOX_INSTALL_MDEV_CONF
>   Luca>  +	install -m 0644 package/busybox/mdev.conf $(TARGET_DIR)/etc
>
> Please use install -D, and only install if the file is not already
> there in the rootfs.

Will do both changes, but I'd like to better understand why this file
should not be installed if already present, which differs from how some
other files are installed.

For example, S10mdev is installed just before mdef.conf (see quoted
lined above) without -D and without checking for existence.

Is there a general policy about this? I did not find one in the docs,
but I might have missed it.

Additionally, if there is a clear policy, it may be useful to have
macros to automate it and make it verifiable, such as:

   INSTALL_FILE = $(INSTALL) -D
   INSTALL_DIR = $(INSTALL) -d
   INSTALL_FOO = $(INSTALL)

or, maybe better, macros with parameters that would be easier to use:

   $(call install_file, $(@D)/foo.conf, 0640, etc/foo)

which may translate to something like:

   [ -f $(TARGET_DIR)/etc/foo/foo.conf ] || \
   $(INSTALL) -D -m 0640 $(@D)/foo.conf $(TARGET_DIR)/etc/foo/foo.conf


Luca

[Buildroot] [PATCH] busybox: provide /etc/mdev.conf if mdev is used

[Peter Korsgaard]

>>>>> "Luca" == Luca Ceresoli <luca@lucaceresoli.net> writes:

Hi,

 >> Please use install -D, and only install if the file is not already
 >> there in the rootfs.

 Luca> Will do both changes, but I'd like to better understand why this file
 Luca> should not be installed if already present, which differs from how some
 Luca> other files are installed.

 Luca> For example, S10mdev is installed just before mdef.conf (see quoted
 Luca> lined above) without -D and without checking for existence.

 Luca> Is there a general policy about this? I did not find one in the docs,
 Luca> but I might have missed it.

The general idea (which isn't followed everywhere unfortunately) is to
not enforce any policy unless we absolutely have to.

This has to be balanced against us wanting BR to work out of the box. As
an example we force enable devtmpfs if you build a kernel and have
devtmpfs /dev option enabled, as it cannot work with the kernel doesn't
have this enabled. Another example is the ARM EABI selection.

Next to these hard options, that we clearly should enforce we have a
number of places where we provide sensible defaults. This is typically
for configuration files. For those we should make it work out of the box
where possible, but still make it possible to override if the user knows
better. Historically this is done in two ways (the 1st has existed for a
very long time, the 2nd is relatively new):

- Use a custom rootfs skeleton with tweaked configuration files
- Use a post-build script to tweak configuration files

For users of the first option, we should ensure that we don't overwrite
custom configuration files, so we need to check if the file already
exists before installing.

For the init script things are a bit more complicated, as the
format/file name depends on the init implementation used. We so far
only handle this through option 2.

And yes, we should probably add this to the docs somewhere.

 Luca> Additionally, if there is a clear policy, it may be useful to have
 Luca> macros to automate it and make it verifiable, such as:

 Luca>   INSTALL_FILE = $(INSTALL) -D
 Luca>   INSTALL_DIR = $(INSTALL) -d
 Luca>   INSTALL_FOO = $(INSTALL)

 Luca> or, maybe better, macros with parameters that would be easier to use:

 Luca>   $(call install_file, $(@D)/foo.conf, 0640, etc/foo)

Yes, ptxdist does something like that. It might be interesting to do so
as well.

The install -D is just for robustness, in case the destination directory
doesn't exist yet.

-- 
Bye, Peter Korsgaard

[Buildroot] [PATCH v2] busybox: provide /etc/mdev.conf if mdev is used

[Luca Ceresoli]

Without an mdev.conf file installed, mdev generates some /dev entries in
an incorrect or non-standard way. Some examples:
 1. /dev/null has permissions 660, but it should be accessible to normal
    users;
 2. alsa devices get created in /dev, not /dev/snd as is more common,
    and as the default value of BR2_PACKAGE_ALSA_LIB_DEVDIR suggests;
 3. event<N> files are created in /dev, not /dev/input.

This mdev.conf is a selection from the examples provided in the busybox
sources with minor tweaks.

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
---

New in v2:
 - use install -D;
 - only install if the file is not already there in the rootfs.

 package/busybox/busybox.mk |    6 ++++++
 package/busybox/mdev.conf  |   35 +++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 0 deletions(-)
 create mode 100644 package/busybox/mdev.conf

diff --git a/package/busybox/busybox.mk b/package/busybox/busybox.mk
index 509c3bb..8998ca0 100644
--- a/package/busybox/busybox.mk
+++ b/package/busybox/busybox.mk
@@ -33,6 +33,11 @@ ifeq ($(BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_MDEV),y)
 define BUSYBOX_INSTALL_MDEV_SCRIPT
 	install -m 0755 package/busybox/S10mdev $(TARGET_DIR)/etc/init.d
 endef
+define BUSYBOX_INSTALL_MDEV_CONF
+	[ -f $(TARGET_DIR)/etc/mdev.conf ] || \
+		install -D -m 0644 package/busybox/mdev.conf \
+			$(TARGET_DIR)/etc/mdev.conf
+endef
 define BUSYBOX_SET_MDEV
 	$(call KCONFIG_ENABLE_OPT,CONFIG_MDEV,$(BUSYBOX_BUILD_CONFIG))
 	$(call KCONFIG_ENABLE_OPT,CONFIG_FEATURE_MDEV_CONF,$(BUSYBOX_BUILD_CONFIG))
@@ -159,6 +164,7 @@ define BUSYBOX_INSTALL_TARGET_CMDS
 			$(TARGET_DIR)/usr/share/udhcpc/default.script; \
 	fi
 	$(BUSYBOX_INSTALL_MDEV_SCRIPT)
+	$(BUSYBOX_INSTALL_MDEV_CONF)
 	$(BUSYBOX_INSTALL_LOGGING_SCRIPT)
 endef
 
diff --git a/package/busybox/mdev.conf b/package/busybox/mdev.conf
new file mode 100644
index 0000000..247c0ed
--- /dev/null
+++ b/package/busybox/mdev.conf
@@ -0,0 +1,35 @@
+# null may already exist; therefore ownership has to be changed with command
+null		root:root 666 @chmod 666 $MDEV
+zero		root:root 666
+full		root:root 666
+random		root:root 444
+urandom		root:root 444
+hwrandom	root:root 444
+grsec		root:root 660
+
+kmem		root:root 640
+mem		root:root 640
+port		root:root 640
+# console may already exist; therefore ownership has to be changed with command
+console		root:tty 600 @chmod 600 $MDEV
+ptmx		root:tty 666
+pty.*		root:tty 660
+
+# Typical devices
+tty		root:tty 666
+tty[0-9]*	root:tty 660
+vcsa*[0-9]*	root:tty 660
+ttyS[0-9]*	root:root 660
+
+# alsa sound devices
+pcm.*		root:audio 660 =snd/
+control.*	root:audio 660 =snd/
+midi.*		root:audio 660 =snd/
+seq		root:audio 660 =snd/
+timer		root:audio 660 =snd/
+
+# input stuff
+event[0-9]+	root:root 640 =input/
+mice		root:root 640 =input/
+mouse[0-9]	root:root 640 =input/
+ts[0-9]		root:root 600 =input/
-- 
1.7.4.1

[Buildroot] [PATCH] busybox: provide /etc/mdev.conf if mdev is used

[Luca Ceresoli]

Peter,

Peter Korsgaard wrote:
>>>>>> "Luca" == Luca Ceresoli<luca@lucaceresoli.net>  writes:
>
> Hi,
>
>   >>  Please use install -D, and only install if the file is not already
>   >>  there in the rootfs.
>
>   Luca>  Will do both changes, but I'd like to better understand why this file
>   Luca>  should not be installed if already present, which differs from how some
>   Luca>  other files are installed.
>
>   Luca>  For example, S10mdev is installed just before mdef.conf (see quoted
>   Luca>  lined above) without -D and without checking for existence.
>
>   Luca>  Is there a general policy about this? I did not find one in the docs,
>   Luca>  but I might have missed it.
>
> The general idea (which isn't followed everywhere unfortunately) is to
> not enforce any policy unless we absolutely have to.
>
> This has to be balanced against us wanting BR to work out of the box. As
> an example we force enable devtmpfs if you build a kernel and have
> devtmpfs /dev option enabled, as it cannot work with the kernel doesn't
> have this enabled. Another example is the ARM EABI selection.
>
> Next to these hard options, that we clearly should enforce we have a
> number of places where we provide sensible defaults. This is typically
> for configuration files. For those we should make it work out of the box
> where possible, but still make it possible to override if the user knows
> better.

Ok, this is much more clear now. Thanks.

> Historically this is done in two ways (the 1st has existed for a
> very long time, the 2nd is relatively new):
>
> - Use a custom rootfs skeleton with tweaked configuration files
> - Use a post-build script to tweak configuration files

There's actually a third way, that is to put custom files in
package/costomize/source. I use it for files that I need to customize, 
nut that would be overwritten by BR if they were in the custom skeleton.

Luca

[Buildroot] [PATCH] busybox: provide /etc/mdev.conf if mdev is used

[Peter Korsgaard]

>>>>> "Luca" == Luca Ceresoli <luca@lucaceresoli.net> writes:

Hi,

 Luca> Ok, this is much more clear now. Thanks.

Great.

 >> Historically this is done in two ways (the 1st has existed for a
 >> very long time, the 2nd is relatively new):
 >> 
 >> - Use a custom rootfs skeleton with tweaked configuration files
 >> - Use a post-build script to tweak configuration files

 Luca> There's actually a third way, that is to put custom files in
 Luca> package/costomize/source. I use it for files that I need to customize,
 Luca> nut that would be overwritten by BR if they were in the custom
 Luca> skeleton.

True, but that imho just pampers over bugs where BR wrongly overwrites
files it shouldn't.

-- 
Bye, Peter Korsgaard

[Buildroot] [PATCH v2] busybox: provide /etc/mdev.conf if mdev is used

[Peter Korsgaard]

>>>>> "Luca" == Luca Ceresoli <luca@lucaceresoli.net> writes:

 Luca> Without an mdev.conf file installed, mdev generates some /dev entries in
 Luca> an incorrect or non-standard way. Some examples:
 Luca>  1. /dev/null has permissions 660, but it should be accessible to normal
 Luca>     users;
 Luca>  2. alsa devices get created in /dev, not /dev/snd as is more common,
 Luca>     and as the default value of BR2_PACKAGE_ALSA_LIB_DEVDIR suggests;
 Luca>  3. event<N> files are created in /dev, not /dev/input.

 Luca> This mdev.conf is a selection from the examples provided in the busybox
 Luca> sources with minor tweaks.

Committed, thanks.

-- 
Bye, Peter Korsgaard