8 files changed, 613 insertions, 0 deletions
diff --git a/repo/system/syslinux/0018-prevent-pow-optimization.patch b/repo/system/syslinux/0018-prevent-pow-optimization.patch
new file mode 100644
index 0000000..0c42c7b
--- /dev/null
+++ b/repo/system/syslinux/0018-prevent-pow-optimization.patch
@@ -0,0 +1,36 @@
+From: Lukas Schwaighofer <lukas@schwaighofer.name>
+Date: Tue, 26 Feb 2019 23:13:58 +0100
+Subject: Prevent optimizing the pow() function
+
+With the current GCC 8.2.0 from Debian, a section of code calling pow() in
+zzjson_parse.c is turned into a sequence calling exp(). Since no exp()
+implementation is available in syslinux those optimizations need to be
+disabled.
+---
+ com32/gpllib/zzjson/zzjson_parse.c | 6 +++++-
+ 1 file changed, 5 insertions(+), 1 deletion(-)
+
+diff --git a/com32/gpllib/zzjson/zzjson_parse.c b/com32/gpllib/zzjson/zzjson_parse.c
+index ecb6f61..e66a9d8 100644
+--- a/com32/gpllib/zzjson/zzjson_parse.c
++++ b/com32/gpllib/zzjson/zzjson_parse.c
+@@ -138,6 +138,10 @@ static ZZJSON *parse_string2(ZZJSON_CONFIG *config) {
+     return zzjson;
+ }
+ 
++static double __attribute__((optimize("O0"))) pow_noopt(double x, double y) {
++	return pow(x, y);
++}
++
+ static ZZJSON *parse_number(ZZJSON_CONFIG *config) {
+     ZZJSON *zzjson;
+     unsigned long long ival = 0, expo = 0;
+@@ -213,7 +217,7 @@ skipexpo:
+     if (dbl) {
+         dval = sign * (long long) ival;
+         dval += sign * frac;
+-        dval *= pow(10.0, (double) signexpo * expo);
++        dval *= pow_noopt(10.0, (double) signexpo * expo);
+     }
+ 
+     zzjson = config->calloc(1, sizeof(ZZJSON));
diff --git a/repo/system/syslinux/fix-sysmacros.patch b/repo/system/syslinux/fix-sysmacros.patch
new file mode 100644
index 0000000..dd622e8
--- /dev/null
+++ b/repo/system/syslinux/fix-sysmacros.patch
@@ -0,0 +1,12 @@
+diff --git a/extlinux/main.c b/extlinux/main.c
+index a7ebd49..69bb164 100644
+--- a/extlinux/main.c
++++ b/extlinux/main.c
+@@ -41,6 +41,7 @@
+ #include <sys/types.h>
+ #include <sys/mount.h>
+ #include <sys/vfs.h>
++#include <sys/sysmacros.h>
+ 
+ #include "linuxioctl.h"
+ 
diff --git a/repo/system/syslinux/gcc-10.patch b/repo/system/syslinux/gcc-10.patch
new file mode 100644
index 0000000..b5bbad0
--- /dev/null
+++ b/repo/system/syslinux/gcc-10.patch
@@ -0,0 +1,109 @@
+From 951928f2cad5682c2844e6bd0f7201236c5d9b66 Mon Sep 17 00:00:00 2001
+From: Merlin Mathesius <mmathesi@redhat.com>
+Date: Wed, 13 May 2020 08:02:27 -0500
+Subject: [PATCH] Workaround multiple definition of symbol errors
+
+---
+ com32/cmenu/Makefile           | 2 +-
+ com32/elflink/ldlinux/Makefile | 2 +-
+ com32/gpllib/Makefile          | 2 +-
+ com32/hdt/Makefile             | 2 +-
+ core/Makefile                  | 2 +-
+ dos/Makefile                   | 2 +-
+ efi/Makefile                   | 2 +-
+ 7 files changed, 7 insertions(+), 7 deletions(-)
+
+diff --git a/com32/cmenu/Makefile b/com32/cmenu/Makefile
+index b81b68ed..2ae989c4 100644
+--- a/com32/cmenu/Makefile
++++ b/com32/cmenu/Makefile
+@@ -49,7 +49,7 @@ makeoutputdirs:
+ 	@mkdir -p $(OBJ)/libmenu
+ 
+ libmenu/libmenu.elf: $(LIBMENU)
+-	$(LD) -shared $(LDFLAGS) -soname $(patsubst %.elf,%.c32,$(@F)) \
++	$(LD) -shared $(LDFLAGS) -z muldefs -soname $(patsubst %.elf,%.c32,$(@F)) \
+ 		-o $@ $^
+ 
+ tidy dist:
+diff --git a/com32/elflink/ldlinux/Makefile b/com32/elflink/ldlinux/Makefile
+index 87c0d362..2be2a01a 100644
+--- a/com32/elflink/ldlinux/Makefile
++++ b/com32/elflink/ldlinux/Makefile
+@@ -33,7 +33,7 @@ endif
+ all: $(BTARGET) ldlinux_lnx.a
+ 
+ ldlinux.elf : $(OBJS)
+-	$(LD) $(LDFLAGS) -soname $(SONAME) -o $@ $^ $(LIBS)
++	$(LD) $(LDFLAGS) -z muldefs -soname $(SONAME) -o $@ $^ $(LIBS)
+ 
+ LNXCFLAGS += -D__export='__attribute__((visibility("default")))'
+ LNXLIBOBJS = get_key.lo
+diff --git a/com32/gpllib/Makefile b/com32/gpllib/Makefile
+index 1fec9145..2d764d0b 100644
+--- a/com32/gpllib/Makefile
++++ b/com32/gpllib/Makefile
+@@ -24,7 +24,7 @@ makeoutputdirs:
+ 		$(addprefix $(OBJ),$(sort $(dir $(LIBOBJS)))),$(b))
+ 
+ libgpl.elf : $(LIBOBJS)
+-	$(LD) -shared $(LDFLAGS) -soname $(patsubst %.elf,%.c32,$(@F)) -o $@ $^
++	$(LD) -shared $(LDFLAGS) -z muldefs -soname $(patsubst %.elf,%.c32,$(@F)) -o $@ $^
+ 
+ tidy dist clean:
+ 	find . \( -name \*.o -o -name .\*.d -o -name \*.tmp \) -print0 | \
+diff --git a/com32/hdt/Makefile b/com32/hdt/Makefile
+index 61736d05..1d947857 100644
+--- a/com32/hdt/Makefile
++++ b/com32/hdt/Makefile
+@@ -52,7 +52,7 @@ QEMU			?= qemu-kvm
+ all: $(MODULES) $(TESTFILES)
+ 
+ hdt.elf : $(OBJS) $(LIBS) $(C_LIBS)
+-	$(LD) $(LDFLAGS) -o $@ $^
++	$(LD) $(LDFLAGS) -z muldefs -o $@ $^
+ 
+ memtest:
+ 	-[ ! -f $(FLOPPY_DIR)/$(MEMTEST) ] && $(WGET) $(MEMTEST_URL) -O $(FLOPPY_DIR)/$(MEMTEST)
+diff --git a/core/Makefile b/core/Makefile
+index 46cb037c..f0cfcbe9 100644
+--- a/core/Makefile
++++ b/core/Makefile
+@@ -156,7 +156,7 @@ LDSCRIPT = $(SRC)/$(ARCH)/syslinux.ld
+ NASM_ELF = elf
+ 
+ %.elf: %.o $(LIBDEP) $(LDSCRIPT) $(AUXLIBS)
+-	$(LD) $(LDFLAGS) -pie -Bsymbolic \
++	$(LD) $(LDFLAGS) -z muldefs -pie -Bsymbolic \
+ 		-T $(LDSCRIPT) \
+ 		--unresolved-symbols=report-all \
+ 		-E --hash-style=gnu -M -o $@ $< \
+diff --git a/dos/Makefile b/dos/Makefile
+index 4c930d19..5d1c72ca 100644
+--- a/dos/Makefile
++++ b/dos/Makefile
+@@ -19,7 +19,7 @@ include $(MAKEDIR)/embedded.mk
+ CFLAGS	+= -D__MSDOS__ -mregparm=3 -DREGPARM=3
+ # CFLAGS  += -DDEBUG
+ 
+-LDFLAGS	 = -T $(SRC)/dosexe.ld
++LDFLAGS	 = -T $(SRC)/dosexe.ld -z muldefs
+ OPTFLAGS = -g
+ INCLUDES = -include code16.h -nostdinc -iwithprefix include \
+ 	   -I$(SRC) -I$(SRC)/.. -I$(SRC)/../libfat \
+diff --git a/efi/Makefile b/efi/Makefile
+index bbf23f24..3dd922d5 100644
+--- a/efi/Makefile
++++ b/efi/Makefile
+@@ -69,7 +69,7 @@ $(OBJS): | $(OBJ)/$(ARCH)
+ BTARGET  = syslinux.efi
+ 
+ syslinux.so: $(OBJS) $(CORE_OBJS) $(LIB_OBJS)
+-	$(LD) $(LDFLAGS) --strip-debug -o $@ $^ -lgnuefi -lefi
++	$(LD) $(LDFLAGS) -z muldefs --strip-debug -o $@ $^ -lgnuefi -lefi
+ 
+ # We need to rename the .hash section because the EFI firmware
+ # linker really doesn't like it.
+-- 
+2.25.1
+
diff --git a/repo/system/syslinux/syslinux.post-upgrade b/repo/system/syslinux/syslinux.post-upgrade
new file mode 100644
index 0000000..9038866
--- /dev/null
+++ b/repo/system/syslinux/syslinux.post-upgrade
@@ -0,0 +1,61 @@
+#!/bin/sh
+
+# find given append opt
+get_append_opt() {
+	awk -v search="$1" '
+		$1 == "append" || $1 == "APPEND" {
+		        split($0, a);
+		        for (i in a) {
+		                if (index(a[i], search) == 1) {
+	        	                print a[i];
+				}	
+			}
+		}' /boot/extlinux.conf | sort | uniq
+}
+
+# print default kernel options
+get_default_opts() {
+	awk '
+		$1 == "append" || $1 == "APPEND" {
+			opts="";
+			space="";
+		        split($0, a);
+		        for (i in a) {
+		                if (i != 1 \
+				    && (index(a[i], "root=") != 1) \
+				    && (index(a[i], "initrd=") != 1) \
+				    && (index(a[i], "modules=") != 1)) {
+	        	                opts = opts space a[i];
+					space = " ";
+				}
+			}
+			print opts;
+		}
+		' /boot/extlinux.conf | sort | uniq
+}
+
+if ! [ -f /boot/extlinux.conf ]; then
+	exit 0
+fi
+
+# check if we already have a generated extlinux.conf
+if grep -q '^# Generated by update-extlinux' /boot/extlinux.conf; then
+	exit 0
+fi
+
+# try fish out the kernel opts from extlinuix.conf's append line
+root=$(get_append_opt 'root=' | head -n 1)
+modules=$(get_append_opt 'modules=' | head -n 1)
+opts=$(get_default_opts | head -n 1)
+
+# populate update-extlinux.conf with the info we know
+if [ -n "$root" ]; then
+	sed -i -e "/^root=/s|.*|$root|g" /etc/update-extlinux.conf
+fi
+if [ -n "$modules" ]; then
+	sed -i -e "/^modules=/s|.*|$modules|g" /etc/update-extlinux.conf
+fi
+if [ -n "$opts" ]; then
+	sed -i -e "/^default_kernel_opts=/s|.*|default_kernel_opts=\"$opts\"|g" /etc/update-extlinux.conf
+fi
+
diff --git a/repo/system/syslinux/syslinux.trigger b/repo/system/syslinux/syslinux.trigger
new file mode 100644
index 0000000..fe91f43
--- /dev/null
+++ b/repo/system/syslinux/syslinux.trigger
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+update-extlinux --warn-only
diff --git a/repo/system/syslinux/syslinux.xibuild b/repo/system/syslinux/syslinux.xibuild
new file mode 100644
index 0000000..19edc66
--- /dev/null
+++ b/repo/system/syslinux/syslinux.xibuild
@@ -0,0 +1,34 @@
+#!/bin/sh
+
+MAKEDEPS="make "
+DEPS="util-linux sbase musl"
+
+PKG_VER=6.03
+SOURCE=https://mirrors.edge.kernel.org/pub/linux/utils/boot/syslinux/${PKG_VER%.*}.xx/syslinux-$PKG_VER.tar.xz
+ADDITIONAL="
+	update-extlinux.conf
+	update-extlinux
+	0018-prevent-pow-optimization.patch
+	fix-sysmacros.patch
+    "
+DESC="Boot loader for the Linux operating system"
+
+prepare () {
+    apply_patches
+}
+
+build () {
+    make efi64 installer
+}
+
+package () {
+    make -j1 INSTALLROOT="$PKG_DEST" MANDIR=/usr/share/man \
+    bios efi64 install
+
+	mkdir -p "$PKG_DEST"/etc/update-extlinux.d
+	cp update-extlinux.conf "$PKG_DEST"/etc/
+	sed "/^version=/s/=.*/=$PKG_VER/" update-extlinux \
+		> "$PKG_DEST"/sbin/update-extlinux
+	chmod 755 "$PKG_DEST"/sbin/update-extlinux
+}
+
diff --git a/repo/system/syslinux/update-extlinux b/repo/system/syslinux/update-extlinux
new file mode 100644
index 0000000..4799cd3
--- /dev/null
+++ b/repo/system/syslinux/update-extlinux
@@ -0,0 +1,284 @@
+#!/bin/sh
+
+version=
+default=0
+timeout=5
+verbose=0
+
+conf=/boot/extlinux.conf
+myconf=/etc/update-extlinux.conf
+
+# read in extlinux settings
+if [ -f "$myconf" ]; then
+	. $myconf
+fi
+
+everbose() {
+	if [ "$verbose" = "0" ]; then
+		return
+	fi
+
+	echo $*
+}
+
+ewarn() {
+	echo "WARNING:" $@ >&2
+}
+
+eerror() {
+	echo "ERROR:" $@ >&2
+	return 1
+}
+
+usage() {
+	echo "usage: $0 [-v|--verbose] [--warn-only]"
+}
+
+while [ $# -gt 0 ]; do
+	opt="$1"
+	shift
+	case "$opt" in
+	-v|--verbose)
+		verbose=1
+		;;
+	--warn-only)
+		warn_only=1
+		;;
+	--)
+		break
+		;;
+	-*)
+		usage
+		exit 1
+		;;
+	esac
+done
+
+everbose "Updating extlinux configuration."
+
+if [ "x$root" = "x" ]; then
+	ewarn "Root device is not specified in $myconf."
+	blkid_export=$(blkid -o export /dev/root)
+	if [ -n "$blkid_export" ]; then
+		export $blkid_export
+	fi
+	if [ -z "$UUID" ]; then
+		# try parse /proc/mount for mounted /
+		dev=$(awk '$2 == "/" {dev=$1} END {print dev}' /proc/mounts)
+		if [ -n "$dev" ]; then
+			blkid_export=$(blkid -o export $dev)
+			if [ -n "$blkid_export" ]; then
+				export "$blkid_export"
+			fi
+		fi
+	fi
+	if [ -z "$UUID" ]; then
+		if [ -z "$dev" ]; then
+			if [ -n "$warn_only" ]; then
+				ewarn "Failed to detect root device. extlinux.conf is not updated"
+				exit 0
+			else
+				eerror "Failed to detect root device"
+				exit 1
+			fi
+		else
+			root=$dev
+		fi
+	else
+		root=UUID=$UUID
+	fi
+	everbose "Root device is: $root"
+fi
+
+rtimeout=$(( ${timeout} * 10 ))
+syslinux_menu=menu.c32
+menu_hidden=
+
+# vesa menu has been requested?
+if [ "$vesa_menu" = "1" ]; then
+	syslinux_menu=vesamenu.c32
+fi
+
+umask 0022
+rm -f $conf.new
+echo "# Generated by update-extlinux $version" > $conf.new
+if [ -n "$serial_port" ]; then
+	echo "SERIAL $serial_port ${serial_baud:-115200}" >> $conf.new
+fi
+echo "DEFAULT $syslinux_menu" >> $conf.new
+echo "PROMPT 0" >> $conf.new
+echo "MENU TITLE XiLinux/$(uname -s) Boot Menu" >> $conf.new
+if [ "$hidden" = "1" ]; then
+	echo "MENU HIDDEN" >> $conf.new
+fi
+echo "MENU AUTOBOOT XiLinux will be booted automatically in # seconds." >> $conf.new
+echo "TIMEOUT $rtimeout" >> $conf.new
+
+lst=0
+if [ -f "/boot/xen.gz" ]; then
+	for kernel in $(find /boot -name "vmlinuz-*" -type f); do
+		tag=$(basename $kernel | cut -b9-)
+		everbose "Found Xen hypervisor: /boot/xen.gz, kernel: $kernel"
+
+		if [ -f "/boot/initramfs-$tag" ]; then
+			everbose "Found initramfs: /boot/initramfs-$tag"
+			initramfs="initramfs-$tag"
+		else
+			initramfs=
+		fi
+		initramfs_stage="${initramfs:+---} $initramfs"
+
+		if [ -f "/boot/amd-ucode.img" ]; then
+			everbose "Found microcode for AMD CPUs: /boot/amd-ucode.img"
+			ucode_image_amd="amd-ucode.img"
+			case "$xen_opts" in
+				*ucode=scan* ) ;;
+				* ) xen_opts="$xen_opts ucode=scan" ;;
+			esac
+		fi
+		if [ -f "/boot/intel-ucode.img" ]; then
+			everbose "Found microcode for Intel CPUs: /boot/intel-ucode.img"
+			ucode_image_intel="intel-ucode.img"
+			case "$xen_opts" in
+				*ucode=scan* ) ;;
+				* ) xen_opts="$xen_opts ucode=scan" ;;
+			esac
+		fi
+		ucode_image_stage="${ucode_image_amd:+---} $ucode_image_amd ${ucode_image_intel:+---} $ucode_image_intel"
+
+		label=xen-$(grep -w -l $tag /usr/share/kernel/*/kernel.release \
+				| cut -d/ -f5)
+		if [ "$label" = "xen-" ]; then
+			label=xen-$lst
+		fi
+
+		dom0_kernel_stage="--- $(basename $kernel) root=$root modules=${modules}${TYPE:+,$TYPE} $default_kernel_opts"
+
+		echo "LABEL $label" >> $conf.new
+		if [ "$label" = "$default" ]; then
+			echo "  MENU DEFAULT" >> $conf.new
+		fi
+		echo "  MENU LABEL Xen + Linux $tag" >> $conf.new
+		echo "  COM32 mboot.c32" >> $conf.new
+		echo "  APPEND xen.gz $xen_opts $dom0_kernel_stage $initramfs_stage $ucode_image_stage" >> $conf.new
+		echo "" >> $conf.new
+		lst=$(($lst + 1))
+	done
+fi
+
+for kernel in $(find /boot -name "vmlinuz*" -type f); do
+	case $kernel in
+	*vmlinuz) tag=vanilla;;
+	*vmlinuz-*)  tag=$(basename $kernel | cut -b9-);;
+	*) continue;;
+	esac
+	everbose "Found kernel: $kernel"
+	label=$(grep -w -l $tag /usr/share/kernel/*/kernel.release | cut -d/ -f5)
+	if [ -z "$label" ]; then
+		if [ "$tag" = vanilla ]; then
+			label="vanilla"
+		else
+			label=$lst
+		fi
+	fi
+	echo "LABEL $label" >> $conf.new
+	if [ "$label" = "$default" ]; then
+		echo "  MENU DEFAULT" >> $conf.new
+	fi
+	echo "  MENU LABEL Linux $tag" >> $conf.new
+	echo "  LINUX $(basename $kernel)" >> $conf.new
+	initrd=
+	if [ -f "/boot/initramfs-$tag" ]; then
+		everbose "Found initramfs: /boot/initramfs-$tag"
+		initrd="initramfs-$tag"
+	fi
+	if [ -f "/boot/amd-ucode.img" ]; then
+		everbose "Found microcode for AMD CPUs: /boot/amd-ucode.img"
+		initrd="amd-ucode.img${initrd:+,}${initrd}"
+	fi
+	if [ -f "/boot/intel-ucode.img" ]; then
+		everbose "Found microcode for Intel CPUs: /boot/intel-ucode.img"
+		initrd="intel-ucode.img${initrd:+,}${initrd}"
+	fi
+	echo "  INITRD ${initrd}" >> $conf.new
+	echo "  APPEND root=$root modules=${modules}${TYPE:+,$TYPE} $default_kernel_opts" >> $conf.new
+	echo "" >> $conf.new
+	lst=$(($lst + 1))
+done
+
+if [ -n "$password" ]; then
+	echo "NOESCAPE 1" >> $conf.new
+	echo "MENU MASTER PASSWD $password" >> $conf.new
+	echo "" >> $conf.new
+	chmod o-r $conf.new
+fi
+
+everbose "$lst entries found."
+
+for entry in /etc/update-extlinux.d/*; do
+	[ -f "$entry" ] && { cat $entry; echo ""; } >> $conf.new
+done
+
+echo "MENU SEPARATOR" >> $conf.new
+echo "" >> $conf.new
+
+if [ -f "/boot/hdt.c32" ]; then
+	everbose "Found Hardware Detection Tool: /boot/hdt.c32"
+	echo "LABEL hdt" >> $conf.new
+	echo "  MENU LABEL Hardware info" >> $conf.new
+	if [ -n "$password" ]; then
+		echo "  MENU PASSWD" >> $conf.new
+	fi
+	echo "  COM32 hdt.c32" >> $conf.new
+	if [ -f "/boot/memtest" ]; then
+		everbose "Found memtest86+: /boot/memtest"
+		echo "  APPEND memtest=memtest" >> $conf.new
+	fi
+	echo "" >> $conf.new
+elif [ -f "/boot/memtest" ]; then
+	everbose "Found memtest86+: /boot/memtest"
+	echo "LABEL memtest" >> $conf.new
+	echo "  MENU LABEL Memtest86+" >> $conf.new
+        echo "  KERNEL memtest" >> $conf.new
+	echo "" >> $conf.new
+fi
+
+for i in reboot poweroff; do
+	[ -f "/boot/$i.c32" ] || continue
+	everbose "Found $i"
+	# make first char capital
+	cap=$( echo $i | awk '{sub(".", substr(toupper($0),1,1), $0); print}' )
+	echo "LABEL $i" >> $conf.new
+	echo "  MENU LABEL $cap" >> $conf.new
+        echo "  COM32 $i.c32" >> $conf.new
+	echo "" >> $conf.new
+done
+
+if cmp -s $conf.new $conf; then
+	everbose "Configuration unchanged."
+	rm $conf.new
+fi
+
+if [ "$overwrite" != "1" ]; then
+	exit 0
+elif [ -f "$conf.new" ]; then
+	# keep a backup just in case
+	if [ -f "$conf" ]; then
+		mv $conf $conf.old
+	fi
+
+	mv $conf.new $conf
+fi
+
+everbose "Installing libutil.c32 libcom32.c32 mboot.c32 menu.c32 vesamenu.c32 to /boot."
+cp /usr/share/syslinux/libutil.c32 \
+	/usr/share/syslinux/libcom32.c32 \
+	/usr/share/syslinux/mboot.c32 \
+	/usr/share/syslinux/menu.c32 \
+	/usr/share/syslinux/vesamenu.c32 \
+	/boot
+
+case "$(findmnt -n -o FSTYPE -T /boot)" in
+ext*) extlinux --update /boot || [ -n "$warn_only" ];;
+esac
+
diff --git a/repo/system/syslinux/update-extlinux.conf b/repo/system/syslinux/update-extlinux.conf
new file mode 100644
index 0000000..1dddff2
--- /dev/null
+++ b/repo/system/syslinux/update-extlinux.conf
@@ -0,0 +1,74 @@
+# configuration for extlinux config builder
+
+# overwrite
+# Overwrite current /boot/extlinux.conf. If this is not '1' we will only
+# write to /boot/extlinux.conf.new
+overwrite=1
+
+# vesa_menu
+# use fancy vesa menu (vesamenu.c32) menus, won't work with serial
+vesa_menu=0
+
+# default_kernel_opts
+# default kernel options
+default_kernel_opts=quiet
+
+# modules
+# modules which should be loaded before pivot_root
+modules=sd-mod,usb-storage,ext4
+
+# root
+# root device - if not specified, will be guessed using
+# blkid -o export /dev/root
+root=
+
+# verbose
+# if set to non-zero, update-extlinux will be a lot more verbose.
+verbose=0
+
+# hidden
+# if set to non-zero, the boot menu will be hidden by default.
+hidden=1
+
+# timeout
+# number of seconds to wait before booting default
+timeout=3
+
+# default
+# default kernel to boot
+default=lts
+
+# serial_port
+# serial port number - if not specified, serial console will be disabled
+serial_port=
+
+# serial_baud
+# the baudrate for the serial port. Will use 115200 if unset
+serial_baud=115200
+
+# xen_opts
+# options to hand to xen hypervisor, useful ones are:
+#    dom0_mem=384M (give domain-0 environment 384M ram)
+xen_opts=dom0_mem=384M
+
+# if you copy /usr/share/syslinux/reboot.c32 to /boot/, a menu entry
+# will be auto-generated for it
+
+# if you copy hdt.c32, libgpl.c32, and libmenu.c32 from /usr/share/syslinux/
+# to /boot/, a menu entry will be auto-generated for HDT
+
+# if you download and install /boot/memtest, then if HDT is present it
+# will use it, else a separate menu entry will be auto-generated for
+# memtest
+
+# optional password
+# you can generate a SHA512 password using: mkpasswd
+#
+# if you assign a password, you should make this file world-unreadable
+#
+# if a password is assigned, the menu entries can't be edited at boot
+# time, and HDT if present is password-protected
+#
+# you can also include "MENU PASSWD" in any custom entries you have in
+# /etc/update-extlinux.d/
+password=''