[Buildroot] [PATCH] fs: allow extra arguments to common tarball extraction

[Carlos Santos <casantos@datacom.com.br>]

> From: "Arnout Vandecappelle" <arnout@mind.be>
> To: "Yann Morin" <yann.morin.1998@free.fr>, "DATACOM" <casantos@datacom.com.br>
> Cc: "Thomas De Schampheleire" <thomas.de_schampheleire@nokia.com>, "buildroot" <buildroot@buildroot.org>
> Sent: Thursday, June 7, 2018 6:03:48 PM
> Subject: Re: [Buildroot] [PATCH] fs: allow extra arguments to common tarball extraction

> On 06-06-18 20:51, Yann E. MORIN wrote:
>> But my position has always been consistent on this topic: the images
>> that Buildroot generates only ever covers just "basic" situations, using
>> a single-filesystem layout. Anything that needs to do a multi-filesystem
>> layout should be done as a new filesystem. Doing it in a new filesystem
>> is much more flexible than whatever kconfig option we may ever add. And
>> since we already have this wonderful flexibility, I don't think it makes
>> sense to add a new option that duplicates only a very limited subset of
>> that flexibility. That duplication is not good, IMNSHO...
> 
> There is (in my even less humble opinion) one way that we can solve this
> generically: by adding a genimage filesystem. genimage is able to create
> separate filesystem images for subtrees. so it can cover many use cases in a
> generic way.

I'm already working on a patch to convert inner-rootfs into a generic
inner-filesystem macro. I will submit it for comments soon.

BTW, it took me some time to understand the dual personality of TARGET_DIR
in fs/common.mk and the role of BASE_TARGET_DIR. Then I found the line in
the top Makefile with

  TARGET_DIR = $(if $(ROOTFS),$(ROOTFS_$(ROOTFS)_TARGET_DIR),$(BASE_TARGET_DIR))

I understand that this trick avoids changing fs/*/*.mk replacing each
reference to TARGET_DIR by a ROOTFS_<FOO>_TARGET_DIR but it reduces
the readability a lot. I'm compelled to restore it to how it was prior
to commit 7e9870ce32d.

-- 
Carlos Santos (Casantos) - DATACOM, P&D
?Marched towards the enemy, spear upright, armed with the certainty
that only the ignorant can have.? ? Epitaph of a volunteer