Arm backend: Added DirectDrive FVP builder script (#18447)

Added a builder script for assembling the DirectDrive FVP

cc @digantdesai @freddan80 @per @zingo @oscarandersson8218 @mansnils
@Sebastian-Larsson @robell

Signed-off-by: Christoffer J.L. <christoffer.johanssonlundqvist@arm.com>
Co-authored-by: Zingo Andersen <zingo.andersen@arm.com>

Author: Christoffer-JL

backends/arm/scripts/build_direct_drive_fvp.sh

@@ -0,0 +1,96 @@
+#!/usr/bin/env bash
+# Copyright 2026 Arm Limited and/or its affiliates.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+apply_patch_if_needed () {
+  local patch="$1"
+  if git apply --reverse --check "$patch" >/dev/null 2>&1; then
+    echo "Already applied: $(basename "$patch")"
+  else
+    git am "$patch"
+  fi
+}
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+
+# Clone repos if not already cloned
+if [[ ! -d meta-arm/.git ]]; then
+  git clone https://git.yoctoproject.org/git/meta-arm -b CORSTONE1000-2025.12 meta-arm
+fi
+if [[ ! -d systemready-patch/.git ]]; then
+  git clone https://git.gitlab.arm.com/arm-reference-solutions/systemready-patch.git \
+    -b topics/hugkam01/a320_with_ssh systemready-patch
+fi
+
+cd meta-arm/
+
+git am --abort 2>/dev/null || true
+
+# Apply patches if not already applied
+# TODO: Remove these patches and the apply_patch_if_needed func once we bump the version
+apply_patch_if_needed ../systemready-patch/embedded-a/corstone1000/remove_second_bank/0001-Platform-Corstone1000-Drop-secondary-bank-reservatio.patch
+apply_patch_if_needed ../systemready-patch/embedded-a/corstone1000/add-ssh-to-a320/0001-kas-Build-Corstone-1000-a320-with-SSH.patch
+
+cd ../
+
+cp systemready-patch/embedded-a/corstone1000/ethos-u85_test/ethos-u85_test.yml meta-arm/kas/
+
+mkdir -p meta-arm/kas/local
+cat > meta-arm/kas/local/enable-ssh.yml <<'EOF'
+header:
+  version: 14
+
+local_conf_header:
+  enable-ssh: |
+    CORE_IMAGE_EXTRA_INSTALL:append = " packagegroup-core-ssh-dropbear ssh-pregen-hostkeys"
+    IMAGE_CLASSES:append = " dropbear-rcs-symlink"
+    CORE_IMAGE_EXTRA_INSTALL:append:firmware = " packagegroup-core-ssh-dropbear ssh-pregen-hostkeys"
+    IMAGE_CLASSES:append:firmware = " dropbear-rcs-symlink"
+  zzz-ssh-autostart: |
+    # Re-add host key generation after other config removes it.
+    CORE_IMAGE_EXTRA_INSTALL:append = " ssh-pregen-hostkeys"
+EOF
+
+mkdir -p meta-arm/meta-arm-bsp/classes/
+cat > meta-arm/meta-arm-bsp/classes/dropbear-rcs-symlink.bbclass <<'EOF'
+ROOTFS_POSTPROCESS_COMMAND:append = " dropbear_rcs_symlink; "
+
+dropbear_rcs_symlink() {
+    if [ -e ${IMAGE_ROOTFS}/etc/init.d/dropbear ]; then
+        rcs_dir=${IMAGE_ROOTFS}/etc/rcS.d
+        install -d ${rcs_dir}
+
+        rm -f ${rcs_dir}/S50dropbear ${rcs_dir}/S50dropbear.sh
+
+        printf '%s\n' \
+            '#!/bin/sh' \
+            '' \
+            'case "$1" in' \
+            'start|"")' \
+            '    if ! pidof dropbear >/dev/null 2>&1; then' \
+            '        if [ -x /etc/init.d/dropbear ]; then' \
+            '            /etc/init.d/dropbear start >/dev/console 2>&1 || \' \
+            '                echo "Dropbear auto-start failed" >/dev/console' \
+            '        fi' \
+            '    fi' \
+            '    ;;' \
+            'esac' \
+            > ${rcs_dir}/S50dropbear.sh
+
+        chmod 0755 ${rcs_dir}/S50dropbear.sh
+    fi
+}
+EOF
+
+if [[ "${ARM_FVP_EULA_ACCEPT:-}" != "1" ]]; then
+    echo "You must export ARM_FVP_EULA_ACCEPT=1 to accept the Arm FVP EULA."
+    exit 1
+fi
+
+kas build meta-arm/kas/corstone1000-a320.yml:meta-arm/ci/debug.yml:meta-arm/kas/ethos-u85_test.yml:meta-arm/kas/local/enable-ssh.yml
+
+kas shell "meta-arm/kas/corstone1000-fvp.yml:meta-arm/ci/debug.yml:meta-arm/kas/corstone1000-a320.yml:meta-arm/kas/local/enable-ssh.yml" -c "bitbake corstone1000-recovery-image -c populate_sdk"