zfsbootmenu/bin/firmware-setup: new utility

reboots to UEFI firmware setup if supported

fixes #423

zfsbootmenu/bin/firmware-setup

@@ -0,0 +1,44 @@
+#!/bin/bash
+
+source /lib/zfsbootmenu-core.sh >/dev/null 2>&1 || exit 1
+
+if ! is_efi_system; then
+    zdebug "efivarfs unsupported"
+    return 1
+elif [ ! -r /sys/firmware/efi/efivars/OsIndicationsSupported-8be4df61-93ca-11d2-aa0d-00e098032b8c ]; then
+    zdebug "OsIndicationsSupported unsupported"
+    return 1
+elif [ ! -r /sys/firmware/efi/efivars/OsIndications-8be4df61-93ca-11d2-aa0d-00e098032b8c ]; then
+    zdebug "OsIndications unsupported"
+    return 1
+fi
+
+# Check if the EFI_OS_INDICATIONS_BOOT_TO_FW_UI = 0x01 bit is set
+if ! (( $(od -An -t u1 -j4 -N1 \
+    /sys/firmware/efi/efivars/OsIndicationsSupported-8be4df61-93ca-11d2-aa0d-00e098032b8c \
+    | tr -dc '0-9') & 1 )); then
+    zdebug "EFI reboot to firmware UI unsupported"
+    return 1
+fi
+
+mount_efivarfs rw
+if [ ! -w /sys/firmware/efi/efivars/OsIndications-8be4df61-93ca-11d2-aa0d-00e098032b8c ]; then
+    zdebug "OsIndications not writable"
+    return 1
+fi
+
+mapfile -t osindications < <(od -An -t x1 -v -w1 \
+    /sys/firmware/efi/efivars/OsIndications-8be4df61-93ca-11d2-aa0d-00e098032b8c | tr -dc '[:alnum:]\n')
+
+# set the required flags:
+# EFI_VARIABLE_NON_VOLATILE = 0x01
+# EFI_VARIABLE_BOOTSERVICE_ACCESS = 0x02
+# EFI_VARIABLE_RUNTIME_ACCESS = 0x04
+osindications[0]=$(( 0x"${osindications[0]}" | 0x07 ))
+
+# Set the EFI_OS_INDICATIONS_BOOT_TO_FW_UI = 0x01 bit
+osindications[4]=$(( 0x"${osindications[4]}" | 0x01 ))
+
+printf "$(printf '\\x%02x' "${osindications[@]}")" > /sys/firmware/efi/efivars/OsIndications-8be4df61-93ca-11d2-aa0d-00e098032b8c
+
+reboot