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authordavidovski <david@davidovski.xyz>2022-03-20 00:00:54 +0000
committerdavidovski <david@davidovski.xyz>2022-03-20 00:00:54 +0000
commit19b9a12a93a45cc02b31de9b40c45029fbf3c569 (patch)
treec2c415813d63b7773fa2a533789a1753b9fee724 /extra/syslinux
parent1daf71c2980b1920bbdc2f07af669ebf6f0f82d6 (diff)
changed the linux kernel configs
Diffstat (limited to 'extra/syslinux')
-rw-r--r--extra/syslinux/0018-prevent-pow-optimization.patch36
-rw-r--r--extra/syslinux/fix-sysmacros.patch12
-rw-r--r--extra/syslinux/gcc-10.patch109
-rw-r--r--extra/syslinux/syslinux.post-upgrade61
-rw-r--r--extra/syslinux/syslinux.trigger3
-rw-r--r--extra/syslinux/update-extlinux284
-rw-r--r--extra/syslinux/update-extlinux.conf74
7 files changed, 579 insertions, 0 deletions
diff --git a/extra/syslinux/0018-prevent-pow-optimization.patch b/extra/syslinux/0018-prevent-pow-optimization.patch
new file mode 100644
index 0000000..0c42c7b
--- /dev/null
+++ b/extra/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/extra/syslinux/fix-sysmacros.patch b/extra/syslinux/fix-sysmacros.patch
new file mode 100644
index 0000000..dd622e8
--- /dev/null
+++ b/extra/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/extra/syslinux/gcc-10.patch b/extra/syslinux/gcc-10.patch
new file mode 100644
index 0000000..b5bbad0
--- /dev/null
+++ b/extra/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/extra/syslinux/syslinux.post-upgrade b/extra/syslinux/syslinux.post-upgrade
new file mode 100644
index 0000000..9038866
--- /dev/null
+++ b/extra/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/extra/syslinux/syslinux.trigger b/extra/syslinux/syslinux.trigger
new file mode 100644
index 0000000..fe91f43
--- /dev/null
+++ b/extra/syslinux/syslinux.trigger
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+update-extlinux --warn-only
diff --git a/extra/syslinux/update-extlinux b/extra/syslinux/update-extlinux
new file mode 100644
index 0000000..4799cd3
--- /dev/null
+++ b/extra/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/extra/syslinux/update-extlinux.conf b/extra/syslinux/update-extlinux.conf
new file mode 100644
index 0000000..1dddff2
--- /dev/null
+++ b/extra/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=''