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Date:   Wed, 22 Apr 2020 22:44:25 +0200
From:   Marek Behun <marek.behun@nic.cz>
To:     Chris Murphy <lists@colorremedies.com>
Cc:     Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: when does btrfs create sparse extents?
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On Wed, 22 Apr 2020 14:26:31 -0600
Chris Murphy <lists@colorremedies.com> wrote:

> But I wonder if other sources of this sparseness has been considered?
> Maybe the build system is creating or preserving sparseness? e.g. `tar
> --hole-detection` or `--sparse` is used.

I don't actually know how the kernel is copied into the /boot directory
in this case.

> Another possibility is Btrfs supports two kinds of holes in the
> on-disk format for sparse files. Maybe uboot only supported the
> original (current default) type, and the bug really fixed the newer
> 'no-holes' feature version?

No, U-Boot did not support holes at all.