Re: [PATCH 8/8] scripts: Add helper script to generate eMMC block device images

[Jerome Forissier <jerome.forissier@linaro.org>]

Hi Jan,


On 8/24/25 09:18, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> As an eMMC block device image may consist of more than just the user
> data partition, provide a helper script that can compose the image from
> boot partitions, an RPMB partition and the user data image. The script
> also does the required size validation and/or rounding.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  scripts/mkemmc.sh | 185 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 185 insertions(+)
>  create mode 100755 scripts/mkemmc.sh
> 
> diff --git a/scripts/mkemmc.sh b/scripts/mkemmc.sh
> new file mode 100755
> index 0000000000..5d40c2889b
> --- /dev/null
> +++ b/scripts/mkemmc.sh
> @@ -0,0 +1,185 @@
> +#!/bin/sh -e
> +#
> +# Create eMMC block device image from boot, RPMB and user data images
> +#
> +# Copyright (c) Siemens, 2025
> +#
> +# Authors:
> +#  Jan Kiszka <jan.kiszka@siemens.com>
> +#
> +# This work is licensed under the terms of the GNU GPL version 2.
> +# See the COPYING file in the top-level directory.
> +#
> +
> +usage() {
> +    echo "$0 [OPTIONS] USER_IMG[:SIZE] OUTPUT_IMG"
> +    echo ""
> +    echo "SIZE must be a power of 2. If no SIZE is specified, the size of USER_ING will"
> +    echo "be used (rounded up)."
> +    echo ""
> +    echo "Supported options:"
> +    echo "  -b BOOT1_IMG[:SIZE]   Add boot partitions. SIZE must be multiples of 128K. If"
> +    echo "                          no SIZE is specified, the size of BOOT_IMG will be"

the size of BOOT1_IMG

> +    echo "                          used (rounded up). BOOT1_IMG will be stored in boot"
> +    echo "                          partition 1, and a boot partition 2 of the same size"
> +    echo "                          will be created as empty (all zeros) unless -B is"
> +    echo "                          specified as well."
> +    echo "  -B BOOT2_IMG          Fill boot partition 2 with BOOT2_IMG. Must be combined"
> +    echo "                          with -b which is also defining the partition size."
> +    echo "  -r RPMB_IMG[:SIZE]    Add RPMB partition. SIZE must be multiples of 128K. If"
> +    echo "                          no SIZE is specified, the size of RPMB_IMG will be"
> +    echo "                          used (rounded up)."
> +    echo "  -h, --help            This help"
> +    echo ""
> +    echo "All SIZE parameters support the units K, M, G. If SIZE is smaller than the"
> +    echo "associated image, it will be truncated in the output image."
> +    exit "$1"
> +}
> +
> +process_size() {
> +    if [ "${4#*:}" = "$4"  ]; then
> +        if ! size=$(stat -L -c %s "$2" 2>/dev/null); then
> +            echo "Missing $1 image '$2'." >&2
> +            exit 1
> +        fi
> +        if [ "$3" = 128 ]; then
> +            size=$(( (size + 128 * 1024 - 1) & ~(128 * 1024 - 1) ))
> +        elif [ $(( size & (size - 1) )) -gt 0 ]; then
> +            n=0
> +            while [ "$size" -gt 0 ]; do
> +                size=$((size >> 1))
> +                n=$((n + 1))
> +            done
> +            size=$((1 << n))
> +        fi
> +    else
> +        value="${4#*:}"
> +        if [ "${value%K}" != "$value" ]; then
> +            size=${value%K}
> +            multiplier=1024
> +        elif [ "${value%M}" != "$value" ]; then
> +            size=${value%M}
> +            multiplier=$((1024 * 1024))
> +        elif [ "${value%G}" != "$value" ]; then
> +            size=${value%G}
> +            multiplier=$((1024 * 1024 * 1024))
> +        else
> +            size=$value
> +            multiplier=1
> +        fi
> +        if [ "$size" -eq "$size" ] 2>/dev/null; then
> +            size=$((size * multiplier))
> +        else
> +            echo "Invalid value '$value' specified for $2 image size." >&2
> +            exit 1
> +        fi
> +        if [ "$3" = 128 ]; then
> +            if [ $(( size & (128 * 1024 - 1) )) -ne 0 ]; then
> +                echo "The $2 image size must be multiples of 128K." >&2
> +                exit 1
> +            fi
> +        elif [ $(( size & (size - 1) )) -gt 0 ]; then
> +            echo "The %2 image size must be power of 2." >&2
> +            exit 1
> +        fi
> +    fi
> +    echo $size
> +}
> +
> +userimg=
> +outimg=
> +bootimg1=
> +bootimg2=/dev/zero
> +bootsz=0
> +rpmbimg=
> +rpmbsz=0
> +
> +while [ $# -gt 0 ]; do
> +    case "$1" in
> +        -b)
> +            shift
> +            [ $# -ge 1 ] || usage 1
> +            bootimg1=${1%%:*}
> +            bootsz=$(process_size boot "$bootimg1" 128 "$1")
> +            shift
> +            ;;
> +        -B)
> +            shift
> +            [ $# -ge 1 ] || usage 1
> +            bootimg2=$1
> +            shift
> +            ;;
> +        -r)
> +            shift
> +            [ $# -ge 1 ] || usage 1
> +            rpmbimg=${1%%:*}
> +            rpmbsz=$(process_size RPMB "$rpmbimg" 128 "$1")
> +            shift
> +            ;;
> +        -h|--help)
> +            usage 0
> +            ;;
> +        *)
> +            if [ -z "$userimg" ]; then
> +                userimg=${1%%:*}
> +                usersz=$(process_size user "$userimg" 2 "$1")
> +            elif [ -z "$outimg" ]; then
> +                outimg=$1
> +            else
> +                usage 1
> +            fi
> +            shift
> +            ;;
> +    esac
> +done
> +
> +[ -n "$outimg" ] || usage 1
> +
> +if [ "$bootsz" -gt $((32640 * 1024)) ]; then
> +    echo "Boot image size is larger than 32640K." >&2
> +    exit 1
> +fi

Should we warn if BOOT1_IMG and/or BOOT2_IMG are truncated as a result
of $bootsz being too small? I can see how providing a larger size can be
useful to be able to later extend the filesystem, but a smaller size is
more likely to indicate an error I suppose?

> +if [ "$rpmbsz" -gt $((16384 * 1024)) ]; then
> +    echo "RPMB image size is larger than 16384K." >&2
> +    exit 1
> +fi> +
> +echo "Creating eMMC image"
> +
> +truncate "$outimg" -s 0
> +pos=0
> +
> +if [ "$bootsz" -gt 0 ]; then
> +    echo "  Boot partition 1 and 2:   $((bootsz / 1024))K each"
> +    blocks=$(( bootsz / (128 * 1024) ))
> +    dd if="$bootimg1" of="$outimg" conv=sparse bs=128K count=$blocks \
> +        status=none
> +    dd if="$bootimg2" of="$outimg" conv=sparse bs=128K count=$blocks \
> +        seek=$blocks status=none
> +    pos=$((2 * bootsz))
> +fi
> +
> +if [ "$rpmbsz" -gt 0 ]; then
> +    echo "  RPMB partition:           $((rpmbsz / 1024))K"
> +    blocks=$(( rpmbsz / (128 * 1024) ))
> +    dd if="$rpmbimg" of="$outimg" conv=sparse bs=128K count=$blocks \
> +        seek=$(( pos / (128 * 1024) )) status=none
> +    pos=$((pos + rpmbsz))
> +fi
> +
> +if [ "$usersz" -lt 1024 ]; then
> +    echo "  User data:                $usersz bytes"
> +elif [ "$usersz" -lt $((1024 * 1024)) ]; then
> +    echo "  User data:                $(( (usersz + 1023) / 1024 ))K ($usersz)"
> +elif [ "$usersz" -lt $((1024 * 1024 * 1024)) ]; then
> +    echo "  User data:                $(( (usersz + 1048575) / 1048576))M ($usersz)"
> +else
> +    echo "  User data:                $(( (usersz + 1073741823) / 1073741824))G ($usersz)"
> +fi
> +dd if="$userimg" of="$outimg" conv=sparse bs=128K seek=$(( pos / (128 * 1024) )) \
> +    count=$(( (usersz + 128 * 1024 - 1) / (128 * 1024) )) status=none
> +pos=$((pos + usersz))
> +truncate "$outimg" -s $pos
> +
> +echo ""
> +echo "Instantiate via '-device emmc,boot-partition-size=$bootsz,rpmb-partition-size=$rpmbsz,drive=$outimg'"

That did not work for me. I had to provide a drive name, not the image path.
An also create PCIe and SDHCI devices. That is:

-device pcie-root-port,id=pcie-root,bus=pcie.0 \
-device sdhci-pci,bus=pcie-root \
-device emmc,boot-partition-size=$bootsz,rpmb-partition-size=$rpmbsz,drive=mmc0
-drive if=none,id=mmc0,file=$outimg,format=raw"

I applied the patches on top of QEMU 10.1.0 if that matters.

Regards,
-- 
Jerome