[Buildroot] [PATCH 1/4] fs/custom: generate complete, partition-based device images

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Dear Yann E. MORIN,

On Fri, 20 Dec 2013 23:32:54 +0100, Yann E. MORIN wrote:

> +Requirements on host packages
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +Depending on what types of partitioning and filesystems are used by your
> ++partition table layout description+, you may have to enable some
> +host-packages in the +Host utilities+ sub-menu.
> +
> +Since the content of a +partition table layout description+ is very
> +specific to a board and/or a project, there is no way for Buildroot to
> +automatically select those host packages, and thus it is your
> +responsibility to select the appropriate ones.
> +
> +For example, for an MBR partitioning, you will have to enable the +host
> +genpart+ package. For FAT filesystems, you will have to enable both of
> ++host dosfstools+ and +host mtools+.

I'll have other comments about the genimages stuff later on, but I got
an idea this night about this specific problem. I don't really like the
fact that the user has to manually enable in menuconfig the relevant
host tools, depending on his genimage .ini configuration file.

What about doing something like:

ROOTFS_CUSTOM_DEPENDENCIES = $(shell fs/custom/genimages --show-depends \
				'$(call qstrip,$(BR2_TARGET_ROOTFS_CUSTOM_PARTITION_TABLE))'

The --show-depends option of genimages would, instead of doing the
normal genimages work, simply parse the .ini file, and return a space
separated list of dependencies needed by the ROOTFS_CUSTOM stuff. Not
only this would make the dependencies automatic for the user, but also
it would allow you to remove the following piece of code from the
custom.mk file:

+# All of the following filesystem generators, or partition managers, are
+# optional, but if they are selected, we may need them, so we need to
+# depend on them
+ifeq ($(BR2_PACKAGE_HOST_DOSFSTOOLS),y)
+ROOTFS_CUSTOM_DEPENDENCIES += host-dosfstools
+endif
+ifeq ($(BR2_PACKAGE_HOST_E2FSPROGS),y)
+ROOTFS_CUSTOM_DEPENDENCIES += host-e2fsprogs
+endif
+ifeq ($(BR2_PACKAGE_HOST_GENEXT2FS),y)
+ROOTFS_CUSTOM_DEPENDENCIES += host-genext2fs
+endif
+ifeq ($(BR2_PACKAGE_HOST_GENPART),y)
+ROOTFS_CUSTOM_DEPENDENCIES += host-genpart
+endif
+ifeq ($(BR2_PACKAGE_HOST_MTOOLS),y)
+ROOTFS_CUSTOM_DEPENDENCIES += host-mtools
+endif
+ifeq ($(BR2_PACKAGE_HOST_PARTED),y)
+ROOTFS_CUSTOM_DEPENDENCIES += host-parted
+endif

What do you think?

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com