[PATCH v2 3/4] defaultenv-2: add support to automatically create an initial GPT table

[Sascha Hauer]

On Wed, Apr 23, 2025 at 04:09:12PM +0200, Marco Felsch wrote:
> This adds the support to automatically create a minimal GPT table.
> 
> gpt-add: A script to add a minimal GPT table compatible to i.MX3/5/6/7
> devices. The initial GPT only contains a barebox-environment partition.
> The script checks for the bootsource to decide the GPT location.
> 
> gpt-rm: A script to remove the GPT header and the protective MBR. The
> script checks for the bootsource to decide which GPT should be scrubbed.
> 
> bbenv-gpt: An initscript which checks for a barebox-environment
> partition if booted from MMC. If no parition was found the script
> triggers the gpt-add script.

Can we have a command for this rather than a script?

We might want to extend this functionality and it looks like the shell
gets to its limits quite fast here.

Sascha

> 
> Signed-off-by: Marco Felsch <m.felsch at pengutronix.de>
> ---
> v2:
> - new
> 
>  defaultenv/defaultenv-2-base/bin/gpt-add    | 40 +++++++++++++++++++++
>  defaultenv/defaultenv-2-base/bin/gpt-rm     | 10 ++++++
>  defaultenv/defaultenv-2-base/init/bbenv-gpt | 16 +++++++++
>  3 files changed, 66 insertions(+)
>  create mode 100644 defaultenv/defaultenv-2-base/bin/gpt-add
>  create mode 100644 defaultenv/defaultenv-2-base/bin/gpt-rm
>  create mode 100644 defaultenv/defaultenv-2-base/init/bbenv-gpt
> 
> diff --git a/defaultenv/defaultenv-2-base/bin/gpt-add b/defaultenv/defaultenv-2-base/bin/gpt-add
> new file mode 100644
> index 000000000000..fa61b1929e20
> --- /dev/null
> +++ b/defaultenv/defaultenv-2-base/bin/gpt-add
> @@ -0,0 +1,40 @@
> +#!/bin/sh
> +
> +bootdev="/dev/${bootsource}${bootsource_instance}"
> +yesno=""
> +
> +if [ ${bootsource} != "mmc" ]; then
> +	exit 0
> +fi
> +
> +# If successful, there is already a GPT or MBR header
> +# TODO: Add hush redirect support to avoid user confusion
> +if parted ${bootdev} print; then
> +	exit 0
> +fi
> +
> +readline "Create an initial GPT for barebox? [y|N]: " yesno
> +
> +# No per default
> +if [ "${yesno}" == "" ]; then
> +	exit 0
> +elif [ "${yesno}" == "n" ]; then
> +	exit 0
> +fi
> +
> +# Check for other user input than 'y'
> +if [ "${yesno}" != "y" ]; then
> +	echo "Unkown value, only 'y' and 'n' are supported"
> +	exit 1
> +fi
> +
> +# Make a default GPT table, with the GPT partition entrie array starting at 2MiB
> +# to have enough space for barebox at the beginning and to overcome legacy
> +# platforms like i.MX3/5/6.
> +parted ${bootdev} mklabel gpt 2MiB || gpt-rm
> +
> +# Add a barebox environment partition with the size of 1MiB which should be
> +# enough for development.
> +parted ${bootdev} mkpart barebox-environment bbenv 3MiB 4MiB || gpt-rm
> +
> +parted ${bootdev} refresh
> diff --git a/defaultenv/defaultenv-2-base/bin/gpt-rm b/defaultenv/defaultenv-2-base/bin/gpt-rm
> new file mode 100644
> index 000000000000..e45c79395504
> --- /dev/null
> +++ b/defaultenv/defaultenv-2-base/bin/gpt-rm
> @@ -0,0 +1,10 @@
> +#!/bin/sh
> +
> +bootdev="/dev/${bootsource}${bootsource_instance}"
> +
> +if [ ${bootsource} != "mmc" ]; then
> +	exit 0
> +fi
> +
> +# Remove protective MBR and GPT from boot device
> +memset -d ${bootdev} 0x100 0x0 0x300
> diff --git a/defaultenv/defaultenv-2-base/init/bbenv-gpt b/defaultenv/defaultenv-2-base/init/bbenv-gpt
> new file mode 100644
> index 000000000000..6756cac9885e
> --- /dev/null
> +++ b/defaultenv/defaultenv-2-base/init/bbenv-gpt
> @@ -0,0 +1,16 @@
> +#!/bin/sh
> +
> +bbenvpart="/dev/${bootsource}${bootsource_instance}.barebox-environment"
> +
> +if [ ${bootsource} != "mmc" ]; then
> +	exit 0
> +fi
> +
> +# TODO:
> +# Add command support to search for a given GPT PartUUID on a block device to
> +# be partition name independent.
> +if [ -e ${bbenvpart} ]; then
> +	exit 0
> +fi
> +
> +gpt-add
> -- 
> 2.39.5
> 
> 
> 

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