diff --git a/README.md b/README.md
index d44942aefd..18d71f489c 100644
--- a/README.md
+++ b/README.md
@@ -829,6 +829,11 @@ $ dd if=shredos-20200412.img of=/dev/sdx (20200412 will be the day you compiled,
 - `make shredos_iso_legacy_defconfig` - build legacy ISO only (64-bit)
 - `make shredos_iso_legacy_i586_defconfig` - build legacy ISO only (32-bit)
 
+#### The following experimental configurations are available for testing:
+
+- `make shredos_iso_extra_defconfig` - build hybrid ISO with extra writeable partition (when burned to USB flash drive) (64-bit)
+- `make shredos_iso_extra_i586_defconfig` - build hybrid ISO with extra writeable partition (when burned to USB flash drive) (32-bit)
+
 Do note that loading a configuration should typically be the last step before `make`.
 
 > **The hybrid ISOs offer the most flexibility over the other formats:**
diff --git a/board/shredos/make_extra_partition.sh b/board/shredos/make_extra_partition.sh
new file mode 100755
index 0000000000..22a622b1a3
--- /dev/null
+++ b/board/shredos/make_extra_partition.sh
@@ -0,0 +1,18 @@
+#!/bin/bash -e
+
+# This file produces the extra FAT16 partition for the shredos_iso_extra_*_defconfig configurations.
+# The partition is appended to the ISO, so that when written to USB a writeable partition is available.
+
+rm "${BINARIES_DIR}"/extra.vfat || true
+
+dd if=/dev/zero of="${BINARIES_DIR}/extra.vfat" bs=50M count=1 || exit 1
+"$HOST_DIR"/sbin/mkfs.vfat -F16 "${BINARIES_DIR}/extra.vfat" || exit 1
+
+"$HOST_DIR"/bin/mmd -i "${BINARIES_DIR}/extra.vfat" ::/boot || exit 1
+
+"$HOST_DIR"/bin/mcopy -p -m -i "${BINARIES_DIR}/extra.vfat" board/shredos/fsoverlay/etc/shredos/version.txt ::/boot/version.txt || exit 1
+"$HOST_DIR"/bin/mcopy -p -m -i "${BINARIES_DIR}/extra.vfat" board/shredos/README.txt ::/README.txt || exit 1
+"$HOST_DIR"/bin/mcopy -p -m -i "${BINARIES_DIR}/extra.vfat" board/shredos/autorun.inf ::/autorun.inf || exit 1
+"$HOST_DIR"/bin/mcopy -p -m -i "${BINARIES_DIR}/extra.vfat" board/shredos/shredos.ico ::/shredos.ico || exit 1
+
+exit 0
diff --git a/build_all_shredos.sh b/build_all_shredos.sh
index 41f40a6d44..950d27493a 100755
--- a/build_all_shredos.sh
+++ b/build_all_shredos.sh
@@ -32,6 +32,7 @@ X64_CONFIGS=(
 	"shredos_img_defconfig"
 	"shredos_iso_defconfig"
 	"shredos_iso_legacy_defconfig"
+	"shredos_iso_extra_defconfig" # experimental
 )
 
 # 32-bit configurations to build:
@@ -40,6 +41,7 @@ X32_CONFIGS=(
 	"shredos_img_i586_defconfig"
 	"shredos_iso_i586_defconfig"
 	"shredos_iso_legacy_i586_defconfig"
+	"shredos_iso_extra_i586_defconfig" # experimental
 )
 
 # Packages always needing rebuild between runs, even for the same architecture.
diff --git a/configs/shredos_iso_extra_defconfig b/configs/shredos_iso_extra_defconfig
new file mode 100644
index 0000000000..aec7bbb618
--- /dev/null
+++ b/configs/shredos_iso_extra_defconfig
@@ -0,0 +1,188 @@
+BR2_x86_64=y
+BR2_x86_nocona=y
+BR2_PACKAGE_GLIBC_UTILS=y
+BR2_TOOLCHAIN_BUILDROOT_CXX=y
+BR2_TOOLCHAIN_GLIBC_GCONV_LIBS_COPY=y
+BR2_CPAN_MIRROR="http://cpan.metacpan.org"
+BR2_TARGET_GENERIC_HOSTNAME="shredos"
+BR2_TARGET_GENERIC_ISSUE="Welcome to ShredOS https://github.com/PartialVolume/shredos.x86_64"
+BR2_INIT_SYSV=y
+BR2_ROOTFS_MERGED_USR=y
+BR2_SYSTEM_BIN_SH_BASH=y
+BR2_SYSTEM_DEFAULT_PATH="/bin:/sbin:/usr/bin:/usr/sbin"
+# BR2_ENABLE_LOCALE_PURGE is not set
+BR2_GENERATE_LOCALE="en_US.UTF-8"
+BR2_SYSTEM_ENABLE_NLS=y
+BR2_TARGET_TZ_INFO=y
+BR2_ROOTFS_OVERLAY="board/shredos/fsoverlay"
+BR2_ROOTFS_POST_BUILD_SCRIPT="board/shredos/make_extra_partition.sh"
+BR2_ROOTFS_POST_IMAGE_SCRIPT="board/shredos/make_iso_file.sh"
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
+BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/shredos/kernel-6.6.22-defconfig.config"
+BR2_PACKAGE_LINUX_TOOLS_CPUPOWER=y
+BR2_PACKAGE_LINUX_TOOLS_PERF=y
+BR2_PACKAGE_LINUX_TOOLS_SELFTESTS=y
+# BR2_PACKAGE_BUSYBOX_SELINUX is not set
+BR2_PACKAGE_FFMPEG=y
+BR2_PACKAGE_FFMPEG_GPL=y
+BR2_PACKAGE_FFMPEG_NONFREE=y
+BR2_PACKAGE_FFMPEG_SWSCALE=y
+BR2_PACKAGE_BZIP2=y
+BR2_PACKAGE_GZIP=y
+BR2_PACKAGE_UNZIP=y
+BR2_PACKAGE_XZ=y
+BR2_PACKAGE_ZIP=y
+BR2_PACKAGE_HEXEDIT=y
+BR2_PACKAGE_BINUTILS=y
+BR2_PACKAGE_GETTEXT=y
+BR2_PACKAGE_GREP=y
+BR2_PACKAGE_LIBTOOL=y
+BR2_PACKAGE_SED=y
+BR2_PACKAGE_DOSFSTOOLS=y
+BR2_PACKAGE_DOSFSTOOLS_FATLABEL=y
+BR2_PACKAGE_DOSFSTOOLS_FSCK_FAT=y
+BR2_PACKAGE_DOSFSTOOLS_MKFS_FAT=y
+BR2_PACKAGE_E2FSPROGS=y
+BR2_PACKAGE_EXFATPROGS=y
+BR2_PACKAGE_ASCII_INVADERS=y
+BR2_PACKAGE_DIRECTFB=y
+BR2_PACKAGE_DIRECTFB_ATI128=y
+BR2_PACKAGE_DIRECTFB_MATROX=y
+BR2_PACKAGE_DIRECTFB_I830=y
+BR2_PACKAGE_FBDUMP=y
+BR2_PACKAGE_FBGRAB=y
+BR2_PACKAGE_FBSET=y
+BR2_PACKAGE_FBTERM=y
+BR2_PACKAGE_FBV=y
+BR2_PACKAGE_MESA3D=y
+BR2_PACKAGE_MESA3D_LLVM=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_CROCUS=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_ETNAVIV=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_I915=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_IRIS=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_LIMA=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_PANFROST=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_R300=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_R600=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_RADEONSI=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_SVGA=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_TEGRA=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_VIRGL=y
+BR2_PACKAGE_MESA3D_VULKAN_DRIVER_INTEL=y
+BR2_PACKAGE_MESA3D_OSMESA_GALLIUM=y
+BR2_PACKAGE_MESA3D_OPENGL_ES=y
+BR2_PACKAGE_LINUX_FIRMWARE=y
+BR2_PACKAGE_LINUX_FIRMWARE_AMDGPU=y
+BR2_PACKAGE_LINUX_FIRMWARE_I915=y
+BR2_PACKAGE_LINUX_FIRMWARE_RADEON=y
+BR2_PACKAGE_LINUX_FIRMWARE_QCOM_VENUS=y
+BR2_PACKAGE_LINUX_FIRMWARE_QCOM_ADRENO=y
+BR2_PACKAGE_LINUX_FIRMWARE_MFC_V8=y
+BR2_PACKAGE_LINUX_FIRMWARE_QUALCOMM_6174=y
+BR2_PACKAGE_LINUX_FIRMWARE_BROADCOM_TIGON3=y
+BR2_PACKAGE_LINUX_FIRMWARE_BNX2X=y
+BR2_PACKAGE_LINUX_FIRMWARE_CXGB4_T4=y
+BR2_PACKAGE_LINUX_FIRMWARE_CXGB4_T5=y
+BR2_PACKAGE_LINUX_FIRMWARE_INTEL_E100=y
+BR2_PACKAGE_LINUX_FIRMWARE_INTEL_ICE=y
+BR2_PACKAGE_LINUX_FIRMWARE_MICROCHIP_VSC85XX_PHY=y
+BR2_PACKAGE_LINUX_FIRMWARE_QLOGIC_4X=y
+BR2_PACKAGE_LINUX_FIRMWARE_RTL_815X=y
+BR2_PACKAGE_LINUX_FIRMWARE_RTL_8169=y
+BR2_PACKAGE_LINUX_FIRMWARE_QLOGIC_2XXX=y
+BR2_PACKAGE_EDID_DECODE=y
+BR2_PACKAGE_HDPARM=y
+BR2_PACKAGE_KBD=y
+BR2_PACKAGE_LM_SENSORS=y
+BR2_PACKAGE_LSHW=y
+BR2_PACKAGE_LSSCSI=y
+BR2_PACKAGE_MINICOM=y
+BR2_PACKAGE_NVME=y
+BR2_PACKAGE_READ_EDID=y
+BR2_PACKAGE_SG3_UTILS=y
+BR2_PACKAGE_SG3_UTILS_PROGS=y
+BR2_PACKAGE_SMARTMONTOOLS=y
+BR2_PACKAGE_SYSSTAT=y
+BR2_PACKAGE_TRIGGERHAPPY=y
+BR2_PACKAGE_PERL=y
+BR2_PACKAGE_PYTHON_PYASN1_MODULES=y
+BR2_PACKAGE_PYTHON_PYBIND=y
+BR2_PACKAGE_PYTHON_PYNDIFF=y
+BR2_PACKAGE_PYTHON_SCAPY=y
+BR2_PACKAGE_LZ4=y
+BR2_PACKAGE_LIBGCRYPT=y
+BR2_PACKAGE_LIBJPEG=y
+BR2_PACKAGE_STB=y
+BR2_PACKAGE_LIBHID=y
+BR2_PACKAGE_JSON_GLIB=y
+BR2_PACKAGE_LIBCURL=y
+BR2_PACKAGE_LIBUPNP=y
+BR2_PACKAGE_KERNEL_CMDLINE_EXTRACTOR=y
+BR2_PACKAGE_LIBCAP=y
+BR2_PACKAGE_LIBSECCOMP=y
+BR2_PACKAGE_NWIPE=y
+BR2_PACKAGE_LIBFRIBIDI=y
+BR2_PACKAGE_NCURSES_WCHAR=y
+BR2_PACKAGE_UTF8PROC=y
+BR2_PACKAGE_HEIRLOOM_MAILX=y
+BR2_PACKAGE_COLLECTD=y
+BR2_PACKAGE_COLLECTD_NTPD=y
+BR2_PACKAGE_XUTIL_UTIL_MACROS=y
+BR2_PACKAGE_IPTABLES=y
+BR2_PACKAGE_LFTP=y
+BR2_PACKAGE_LFTP_PROTO_SFTP=y
+BR2_PACKAGE_NMAP=y
+BR2_PACKAGE_NTP=y
+BR2_PACKAGE_NTP_NTPDATE=y
+BR2_PACKAGE_NTP_NTPTIME=y
+BR2_PACKAGE_OPENSSH=y
+# BR2_PACKAGE_OPENSSH_SERVER is not set
+BR2_PACKAGE_RPCBIND=y
+BR2_PACKAGE_SNMPCLITOOLS=y
+BR2_PACKAGE_TFTPD=y
+BR2_PACKAGE_TRACEROUTE=y
+BR2_PACKAGE_WIREGUARD_TOOLS=y
+BR2_PACKAGE_RESTORECOND=y
+BR2_PACKAGE_SELINUX_PYTHON=y
+BR2_PACKAGE_SELINUX_PYTHON_AUDIT2ALLOW=y
+BR2_PACKAGE_PARALLEL=y
+BR2_PACKAGE_TMUX=y
+BR2_PACKAGE_OPENSEACHEST=y
+BR2_PACKAGE_PROCPS_NG=y
+BR2_PACKAGE_RUNC=y
+BR2_PACKAGE_UTIL_LINUX_BINARIES=y
+BR2_PACKAGE_UTIL_LINUX_AGETTY=y
+BR2_PACKAGE_UTIL_LINUX_FSCK=y
+BR2_PACKAGE_UTIL_LINUX_LAST=y
+BR2_PACKAGE_UTIL_LINUX_LOGIN=y
+BR2_PACKAGE_UTIL_LINUX_MOUNT=y
+BR2_PACKAGE_UTIL_LINUX_MOUNTPOINT=y
+BR2_PACKAGE_UTIL_LINUX_PIVOT_ROOT=y
+BR2_PACKAGE_UTIL_LINUX_RFKILL=y
+BR2_PACKAGE_UTIL_LINUX_RUNUSER=y
+BR2_PACKAGE_UTIL_LINUX_SETTERM=y
+BR2_PACKAGE_UTIL_LINUX_SU=y
+BR2_PACKAGE_UTIL_LINUX_SULOGIN=y
+BR2_TARGET_ROOTFS_CPIO_LZMA=y
+BR2_TARGET_ROOTFS_INITRAMFS=y
+BR2_TARGET_ROOTFS_ISO9660=y
+BR2_TARGET_ROOTFS_ISO9660_BOTH=y
+BR2_TARGET_ROOTFS_ISO9660_ISOLINUX_BOOT_MENU="board/shredos/iso/isolinux.cfg"
+BR2_TARGET_ROOTFS_ISO9660_GRUB2_BOOT_MENU="board/shredos/iso/grub.cfg"
+BR2_TARGET_ROOTFS_ISO9660_GRUB2_EFI_BOOT_MENU="board/shredos/iso/efigrub.cfg"
+BR2_TARGET_ROOTFS_ISO9660_GRUB2_EFI_IDENT_FILE="/boot/shredos.id"
+BR2_TARGET_ROOTFS_ISO9660_HYBRID=y
+BR2_TARGET_ROOTFS_ISO9660_HYBRID_APPEND_PARTITION="extra.vfat"
+# BR2_TARGET_ROOTFS_TAR is not set
+BR2_TARGET_GRUB2=y
+BR2_TARGET_GRUB2_X86_64_EFI=y
+BR2_TARGET_GRUB2_BUILTIN_MODULES_EFI="boot linux ext2 fat squash4 part_msdos part_gpt normal progress efi_gop efi_uga all_video video_cirrus video_bochs net efinet tftp gzio test eval read true gfxterm gfxterm_menu gfxmenu gfxterm_background png usb usb_keyboard search configfile iso9660"
+BR2_TARGET_GRUB2_BUILTIN_CONFIG_EFI="board/shredos/embed/grub.cfg"
+BR2_TARGET_GRUB2_INSTALL_TOOLS=y
+BR2_TARGET_SYSLINUX=y
+BR2_PACKAGE_HOST_E2FSPROGS=y
+BR2_PACKAGE_HOST_GENIMAGE=y
+BR2_PACKAGE_HOST_PYTHON3=y
+BR2_PACKAGE_HOST_PYTHON3_BZIP2=y
+BR2_PACKAGE_HOST_PYTHON3_SSL=y
diff --git a/configs/shredos_iso_extra_i586_defconfig b/configs/shredos_iso_extra_i586_defconfig
new file mode 100644
index 0000000000..cabeef7d25
--- /dev/null
+++ b/configs/shredos_iso_extra_i586_defconfig
@@ -0,0 +1,185 @@
+BR2_PACKAGE_GLIBC_UTILS=y
+BR2_TOOLCHAIN_BUILDROOT_CXX=y
+BR2_TOOLCHAIN_GLIBC_GCONV_LIBS_COPY=y
+BR2_CPAN_MIRROR="http://cpan.metacpan.org"
+BR2_TARGET_GENERIC_HOSTNAME="shredos"
+BR2_TARGET_GENERIC_ISSUE="Welcome to ShredOS https://github.com/PartialVolume/shredos.x86_64"
+BR2_INIT_SYSV=y
+BR2_ROOTFS_MERGED_USR=y
+BR2_SYSTEM_BIN_SH_BASH=y
+BR2_SYSTEM_DEFAULT_PATH="/bin:/sbin:/usr/bin:/usr/sbin"
+# BR2_ENABLE_LOCALE_PURGE is not set
+BR2_GENERATE_LOCALE="en_US.UTF-8"
+BR2_SYSTEM_ENABLE_NLS=y
+BR2_TARGET_TZ_INFO=y
+BR2_ROOTFS_OVERLAY="board/shredos/fsoverlay"
+BR2_ROOTFS_POST_BUILD_SCRIPT="board/shredos/make_extra_partition.sh"
+BR2_ROOTFS_POST_IMAGE_SCRIPT="board/shredos/make_iso_file.sh"
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
+BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/shredos/kernel-6.6.22-defconfig.config"
+BR2_PACKAGE_LINUX_TOOLS_CPUPOWER=y
+BR2_PACKAGE_LINUX_TOOLS_PERF=y
+BR2_PACKAGE_LINUX_TOOLS_SELFTESTS=y
+# BR2_PACKAGE_BUSYBOX_SELINUX is not set
+BR2_PACKAGE_FFMPEG=y
+BR2_PACKAGE_FFMPEG_GPL=y
+BR2_PACKAGE_FFMPEG_NONFREE=y
+BR2_PACKAGE_FFMPEG_SWSCALE=y
+BR2_PACKAGE_BZIP2=y
+BR2_PACKAGE_GZIP=y
+BR2_PACKAGE_UNZIP=y
+BR2_PACKAGE_XZ=y
+BR2_PACKAGE_ZIP=y
+BR2_PACKAGE_HEXEDIT=y
+BR2_PACKAGE_BINUTILS=y
+BR2_PACKAGE_GETTEXT=y
+BR2_PACKAGE_GREP=y
+BR2_PACKAGE_LIBTOOL=y
+BR2_PACKAGE_SED=y
+BR2_PACKAGE_DOSFSTOOLS=y
+BR2_PACKAGE_DOSFSTOOLS_FATLABEL=y
+BR2_PACKAGE_DOSFSTOOLS_FSCK_FAT=y
+BR2_PACKAGE_DOSFSTOOLS_MKFS_FAT=y
+BR2_PACKAGE_E2FSPROGS=y
+BR2_PACKAGE_EXFATPROGS=y
+BR2_PACKAGE_ASCII_INVADERS=y
+BR2_PACKAGE_DIRECTFB=y
+BR2_PACKAGE_DIRECTFB_ATI128=y
+BR2_PACKAGE_DIRECTFB_MATROX=y
+BR2_PACKAGE_DIRECTFB_I830=y
+BR2_PACKAGE_FBDUMP=y
+BR2_PACKAGE_FBGRAB=y
+BR2_PACKAGE_FBSET=y
+BR2_PACKAGE_FBTERM=y
+BR2_PACKAGE_FBV=y
+BR2_PACKAGE_MESA3D=y
+BR2_PACKAGE_MESA3D_LLVM=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_CROCUS=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_ETNAVIV=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_I915=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_IRIS=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_LIMA=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_PANFROST=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_R300=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_R600=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_RADEONSI=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_SVGA=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_TEGRA=y
+BR2_PACKAGE_MESA3D_GALLIUM_DRIVER_VIRGL=y
+BR2_PACKAGE_MESA3D_VULKAN_DRIVER_INTEL=y
+BR2_PACKAGE_MESA3D_OSMESA_GALLIUM=y
+BR2_PACKAGE_MESA3D_OPENGL_ES=y
+BR2_PACKAGE_LINUX_FIRMWARE=y
+BR2_PACKAGE_LINUX_FIRMWARE_AMDGPU=y
+BR2_PACKAGE_LINUX_FIRMWARE_I915=y
+BR2_PACKAGE_LINUX_FIRMWARE_RADEON=y
+BR2_PACKAGE_LINUX_FIRMWARE_QCOM_VENUS=y
+BR2_PACKAGE_LINUX_FIRMWARE_QCOM_ADRENO=y
+BR2_PACKAGE_LINUX_FIRMWARE_MFC_V8=y
+BR2_PACKAGE_LINUX_FIRMWARE_QUALCOMM_6174=y
+BR2_PACKAGE_LINUX_FIRMWARE_BROADCOM_TIGON3=y
+BR2_PACKAGE_LINUX_FIRMWARE_BNX2X=y
+BR2_PACKAGE_LINUX_FIRMWARE_CXGB4_T4=y
+BR2_PACKAGE_LINUX_FIRMWARE_CXGB4_T5=y
+BR2_PACKAGE_LINUX_FIRMWARE_INTEL_E100=y
+BR2_PACKAGE_LINUX_FIRMWARE_INTEL_ICE=y
+BR2_PACKAGE_LINUX_FIRMWARE_MICROCHIP_VSC85XX_PHY=y
+BR2_PACKAGE_LINUX_FIRMWARE_QLOGIC_4X=y
+BR2_PACKAGE_LINUX_FIRMWARE_RTL_815X=y
+BR2_PACKAGE_LINUX_FIRMWARE_RTL_8169=y
+BR2_PACKAGE_LINUX_FIRMWARE_QLOGIC_2XXX=y
+BR2_PACKAGE_EDID_DECODE=y
+BR2_PACKAGE_HDPARM=y
+BR2_PACKAGE_KBD=y
+BR2_PACKAGE_LM_SENSORS=y
+BR2_PACKAGE_LSHW=y
+BR2_PACKAGE_LSSCSI=y
+BR2_PACKAGE_MINICOM=y
+BR2_PACKAGE_NVME=y
+BR2_PACKAGE_READ_EDID=y
+BR2_PACKAGE_SG3_UTILS=y
+BR2_PACKAGE_SG3_UTILS_PROGS=y
+BR2_PACKAGE_SMARTMONTOOLS=y
+BR2_PACKAGE_SYSSTAT=y
+BR2_PACKAGE_TRIGGERHAPPY=y
+BR2_PACKAGE_PERL=y
+BR2_PACKAGE_PYTHON_PYASN1_MODULES=y
+BR2_PACKAGE_PYTHON_PYBIND=y
+BR2_PACKAGE_PYTHON_PYNDIFF=y
+BR2_PACKAGE_PYTHON_SCAPY=y
+BR2_PACKAGE_LZ4=y
+BR2_PACKAGE_LIBGCRYPT=y
+BR2_PACKAGE_STB=y
+BR2_PACKAGE_LIBHID=y
+BR2_PACKAGE_JSON_GLIB=y
+BR2_PACKAGE_LIBCURL=y
+BR2_PACKAGE_LIBUPNP=y
+BR2_PACKAGE_KERNEL_CMDLINE_EXTRACTOR=y
+BR2_PACKAGE_LIBCAP=y
+BR2_PACKAGE_LIBSECCOMP=y
+BR2_PACKAGE_NWIPE=y
+BR2_PACKAGE_LIBFRIBIDI=y
+BR2_PACKAGE_NCURSES_WCHAR=y
+BR2_PACKAGE_UTF8PROC=y
+BR2_PACKAGE_HEIRLOOM_MAILX=y
+BR2_PACKAGE_COLLECTD=y
+BR2_PACKAGE_COLLECTD_NTPD=y
+BR2_PACKAGE_XUTIL_UTIL_MACROS=y
+BR2_PACKAGE_IPTABLES=y
+BR2_PACKAGE_LFTP=y
+BR2_PACKAGE_LFTP_PROTO_SFTP=y
+BR2_PACKAGE_NMAP=y
+BR2_PACKAGE_NTP=y
+BR2_PACKAGE_NTP_NTPDATE=y
+BR2_PACKAGE_NTP_NTPTIME=y
+BR2_PACKAGE_OPENSSH=y
+# BR2_PACKAGE_OPENSSH_SERVER is not set
+BR2_PACKAGE_RPCBIND=y
+BR2_PACKAGE_SNMPCLITOOLS=y
+BR2_PACKAGE_TFTPD=y
+BR2_PACKAGE_TRACEROUTE=y
+BR2_PACKAGE_WIREGUARD_TOOLS=y
+BR2_PACKAGE_RESTORECOND=y
+BR2_PACKAGE_SELINUX_PYTHON=y
+BR2_PACKAGE_SELINUX_PYTHON_AUDIT2ALLOW=y
+BR2_PACKAGE_PARALLEL=y
+BR2_PACKAGE_TMUX=y
+BR2_PACKAGE_OPENSEACHEST=y
+BR2_PACKAGE_PROCPS_NG=y
+BR2_PACKAGE_RUNC=y
+BR2_PACKAGE_UTIL_LINUX_BINARIES=y
+BR2_PACKAGE_UTIL_LINUX_AGETTY=y
+BR2_PACKAGE_UTIL_LINUX_FSCK=y
+BR2_PACKAGE_UTIL_LINUX_LAST=y
+BR2_PACKAGE_UTIL_LINUX_LOGIN=y
+BR2_PACKAGE_UTIL_LINUX_MOUNT=y
+BR2_PACKAGE_UTIL_LINUX_MOUNTPOINT=y
+BR2_PACKAGE_UTIL_LINUX_PIVOT_ROOT=y
+BR2_PACKAGE_UTIL_LINUX_RFKILL=y
+BR2_PACKAGE_UTIL_LINUX_RUNUSER=y
+BR2_PACKAGE_UTIL_LINUX_SETTERM=y
+BR2_PACKAGE_UTIL_LINUX_SU=y
+BR2_PACKAGE_UTIL_LINUX_SULOGIN=y
+BR2_TARGET_ROOTFS_CPIO_LZMA=y
+BR2_TARGET_ROOTFS_INITRAMFS=y
+BR2_TARGET_ROOTFS_ISO9660=y
+BR2_TARGET_ROOTFS_ISO9660_BOTH=y
+BR2_TARGET_ROOTFS_ISO9660_ISOLINUX_BOOT_MENU="board/shredos/iso/isolinux.cfg"
+BR2_TARGET_ROOTFS_ISO9660_GRUB2_BOOT_MENU="board/shredos/iso/grub.cfg"
+BR2_TARGET_ROOTFS_ISO9660_GRUB2_EFI_BOOT_MENU="board/shredos/iso/efigrub.cfg"
+BR2_TARGET_ROOTFS_ISO9660_GRUB2_EFI_IDENT_FILE="/boot/shredos.id"
+BR2_TARGET_ROOTFS_ISO9660_HYBRID=y
+BR2_TARGET_ROOTFS_ISO9660_HYBRID_APPEND_PARTITION="extra.vfat"
+# BR2_TARGET_ROOTFS_TAR is not set
+BR2_TARGET_GRUB2=y
+BR2_TARGET_GRUB2_I386_EFI=y
+BR2_TARGET_GRUB2_BUILTIN_MODULES_EFI="boot linux ext2 fat squash4 part_msdos part_gpt normal progress efi_gop efi_uga all_video video_cirrus video_bochs net efinet tftp gzio test eval read true gfxterm gfxterm_menu gfxmenu gfxterm_background png usb usb_keyboard search configfile iso9660"
+BR2_TARGET_GRUB2_BUILTIN_CONFIG_EFI="board/shredos/embed/grub.cfg"
+BR2_TARGET_GRUB2_INSTALL_TOOLS=y
+BR2_TARGET_SYSLINUX=y
+BR2_PACKAGE_HOST_E2FSPROGS=y
+BR2_PACKAGE_HOST_GENIMAGE=y
+BR2_PACKAGE_HOST_PYTHON3=y
+BR2_PACKAGE_HOST_PYTHON3_BZIP2=y
+BR2_PACKAGE_HOST_PYTHON3_SSL=y
diff --git a/fs/iso9660/Config.in b/fs/iso9660/Config.in
index 5f30f5c9a2..c66367ce35 100644
--- a/fs/iso9660/Config.in
+++ b/fs/iso9660/Config.in
@@ -176,6 +176,21 @@ config BR2_TARGET_ROOTFS_ISO9660_HYBRID
 	  that can either be burned to CD/DVD-ROM or flashed onto a device
 	  which the BIOS considers as HDD/removable device (e.g. USB stick)
 
+config BR2_TARGET_ROOTFS_ISO9660_HYBRID_APPEND_PARTITION
+	string "Append hybrid partition image"
+	depends on BR2_TARGET_ROOTFS_ISO9660_BOTH \
+		&& BR2_TARGET_ROOTFS_ISO9660_HYBRID
+	default ""
+	help
+	  Enable this option to append a prepared FAT16 filesystem
+	  image to the hybrid image, useful when needing a writeable
+	  data partition for USBs - should be considered EXPERIMENTAL.
+
+	  The path is expected to be relative to folder "output/images/".
+
+	  You can use e.g. a BR2_ROOTFS_POST_BUILD_SCRIPT for preparing
+	  the respective filesystem image for your target configuration.
+
 endif
 
 comment "iso image needs a Linux kernel and either grub2 or isolinux to be built"
diff --git a/fs/iso9660/iso9660.mk b/fs/iso9660/iso9660.mk
index 14f13af88c..5feea015a4 100644
--- a/fs/iso9660/iso9660.mk
+++ b/fs/iso9660/iso9660.mk
@@ -34,6 +34,7 @@ ROOTFS_ISO9660_GRUB2_EFI_BOOT_MENU = $(call qstrip,$(BR2_TARGET_ROOTFS_ISO9660_G
 ROOTFS_ISO9660_GRUB2_EFI_PARTITION_SIZE = $(call qstrip,$(BR2_TARGET_ROOTFS_ISO9660_GRUB2_EFI_PARTITION_SIZE))
 ROOTFS_ISO9660_GRUB2_EFI_IDENT_FILE = $(call qstrip,$(BR2_TARGET_ROOTFS_ISO9660_GRUB2_EFI_IDENT_FILE))
 ROOTFS_ISO9660_ISOLINUX_BOOT_MENU = $(call qstrip,$(BR2_TARGET_ROOTFS_ISO9660_ISOLINUX_BOOT_MENU))
+ROOTFS_ISO9660_HYBRID_APPEND_PARTITION = $(call qstrip,$(BR2_TARGET_ROOTFS_ISO9660_HYBRID_APPEND_PARTITION))
 
 ################################################################################
 # Architecture-specific variables
@@ -428,6 +429,12 @@ ROOTFS_ISO9660_OPTS += \
 	$(ROOTFS_ISO9660_OPTS_BIOS) \
 	-eltorito-alt-boot \
 	$(ROOTFS_ISO9660_OPTS_EFI)
+# Append an extra FAT16 partition image (if one was provided, for hybrid mode)
+ifneq ($(ROOTFS_ISO9660_HYBRID_APPEND_PARTITION),)
+ROOTFS_ISO9660_OPTS += \
+	-append_partition 3 0x0e $(BINARIES_DIR)/$(ROOTFS_ISO9660_HYBRID_APPEND_PARTITION) \
+	-partition_cyl_align all
+endif
 
 else ifeq ($(BR2_TARGET_ROOTFS_ISO9660_BIOS_BOOTLOADER),y)
 # BIOS