harvey/util/SYSLINUX

qemu-img create -f qcow2 harvey.qcow2 3G
sudo modprobe nbd max_part=63
sudo qemu-nbd -c /dev/nbd0 harvey.qcow2
sudo fdisk /dev/nbd0
[Create an ext2 partition]
sudo extlinux -i /dev/nbd0p1
sudo mount /dev/nbd0p1 disk/
sudo cp ../sys/src/9/amd64/harvey.32bit disk/harvey

cd disk/

$ ls -l
total 5964
-rwxr-xr-x 1 root root 5884264 jun  8 02:16 harvey
-r--r--r-- 1 root root  116624 jun  7 02:12 ldlinux.c32
-r--r--r-- 1 root root   61440 jun  7 02:12 ldlinux.sys
drwx------ 2 root root   16384 jun  7 02:10 lost+found
drwxr-xr-x 2 root root    4096 jun  8 02:25 syslinux
$ ls -l syslinux/
total 280
-rw-r--r-- 1 root root 182552 jun  7 02:34 libcom32.c32
-rw-r--r-- 1 root root  23480 jun  7 02:34 libutil.c32
-rw-r--r-- 1 root root  10172 jun  8 01:29 mboot.c32
-rw-r--r-- 1 root root  25668 jun  7 02:34 menu.c32
-rw-r--r-- 1 root root    727 jun  8 02:05 syslinux.cfg
-rw-r--r-- 1 root root  26188 jun  7 02:25 vesamenu.c32

[modules are into /usr/lib/syslinux/modules/bios/ so copy it from there]

$ cat syslinux/syslinux.cfg 
# syslinux.cfg
#TIMEOUT = Time to wait to autoboot in 1/10 secs. zero (0) disables the timeout 
#PROMPT = one (1) displays the prompt only, zero (0) will not display the prompt
#ONTIMEOUT = The default menu label to automatically boot at timeout (selected after timeout)
#DISPLAY = Optional menu text if not using LABEL Entries

TIMEOUT 1000
DEFAULT vesamenu.c32
#MENU BACKGROUND /backgroundimages/your_image_here.png
MENU TITLE Harvey OS
PROMPT 0
ONTIMEOUT 1
#DISPLAY Menu.txt

#Display help text when F1 pressed on Syslinux Menu
F1 help.txt

LABEL 0
MENU LABEL Reboot
TEXT HELP
Restart the computer
ENDTEXT
COM32 reboot.c32

LABEL 1
TEXT HELP
Boot Harvey kernel
ENDTEXT
MENU LABEL Harvey OS
KERNEL mboot.c32
APPEND ../harvey

sudo umount disk/

[Run qemu]

qemu-system-x86_64 --enable-kvm -s -cpu core2duo -smp 2 -m 2048 -monitor stdio -serial /dev/pts/4 --machine pc -net nic,model=rtl8139 -net user,hostfwd=tcp::5555-:23 -drive file=/media/backup1/source/plan9/harvey/util/harvey.qcow2,media=disk,index=0,cache=writeback