Re: [Buildroot] [RFC PATCH 1/2] support/scripts/genimage.sh: support creating a bmap image

From: Thomas Petazzoni via buildroot <buildroot@buildroot.org>
To: Peter Korsgaard <peter@korsgaard.com>
Cc: michael@amarulasolutions.com, Xuanhao Shi <X15000177@gmail.com>,
	Thomas Petazzoni via buildroot <buildroot@buildroot.org>,
	Dario Binacchi <dario.binacchi@amarulasolutions.com>,
	linux-amarula@amarulasolutions.com,
	Anand Gadiyar <gadiyar@ti.com>
Subject: Re: [Buildroot] [RFC PATCH 1/2] support/scripts/genimage.sh: support creating a bmap image
Date: Fri, 30 Aug 2024 17:29:20 +0200	[thread overview]
Message-ID: <20240830172920.0ede0f66@windsurf> (raw)
In-Reply-To: <87le0e32jm.fsf@dell.be.48ers.dk>

Hello Peter,

On Fri, 30 Aug 2024 09:14:37 +0200
Peter Korsgaard <peter@korsgaard.com> wrote:

> Does such a tool exist? I am not aware of one. If so, maybe we should
> recommend that instead of dd for writing sdcard.img from the host?

I'm not aware of any tool like this.

> 
> Anyway, I find bmap a bit half-baked, E.G. rather than wasting time (and
> space) compressing and decompressing all the holes that are then just
> ignored it would make more sense to have a file format encoding the
> holes (E.G. tar --sparse or something custom), then optionally compress
> that for transmission and have something small and simple (E.G. not in
> python) on the host/target to write it to a device.

The Android sparse image format looks like to be what you want.
See https://2net.co.uk/tutorial/android-sparse-image-format. There are some
C/C++ tools at https://android.googlesource.com/platform/system/core/+/master/libsparse/
to generate/manipulate Android sparse images.

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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