Linux for the Sega MegaDrive

Linux for the Sega MegaDrive

No

• A Sega Megadrive
• Mega EverDrive Core or Pro (pro is untested) (See: https://krikzz.com/our-products/cartridges/)
• USB cable between the EverDrive and your PC
• Time to burn

Probably not, the emulator would need to emulate the EverDrive's special SSF2

mapper that gives us 4MB of RAM, the EverDrive's protocol that allows the MegaDrive to load files from the SD card and the timer register the EverDrive provides.

A QEMU fork that emulates enough of the MegaDrive and the EverDrive to play with this without the real hardware is included. Note that this doesn't really emulate the feel of the real thing, QEMU emulates the CPU way too fast.

Run

./buildtoolchain.sh

to build a toolchain. This uses buildroot but we do not build a root filesystem with it. buildroot is the least painful way to get a m68k-linux toolchain that can produce usable binaries for 68000. - Run

./builduboot.sh

to use the toolchain to build u-boot. - Run

./buildmedtool.sh

to buildmedtool

to interact with the everdrive for serial console. - Run

./buildlinux.sh

to build the linux kernel image. - Run

./buildrootfs.sh

to build the rootfs erofs image.

Run

./buildqemu.sh

to build QEMU - Run

./runqemu.sh

to run QEMU and boot.

Copy

u-boot/u-boot.bin

,linux/vmlinux.lz4

,smolutils/m68k.erofs

to your EverDrive SD card - Power up the Megadrive

Connect the USB cable to your PC (It might be OK to connect it while the Megadrive is off but I had issues with it)

Check your dmesg to make sure the EverDrive is detected. You should see something like this:

[1135618.045606] usb 3-2: new full-speed USB device number 5 using xhci_hcd
[1135618.255415] usb 3-2: New USB device found, idVendor=0483, idProduct=5740, bcdDevice= 2.00
[1135618.255428] usb 3-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[1135618.255430] usb 3-2: Product: Mega EverDrive
[1135618.255432] usb 3-2: Manufacturer: STMicroelectronics
[1135618.255434] usb 3-2: SerialNumber: 00000000001A
[1135618.307393] cdc_acm 3-2:1.0: ttyACM0: USB ACM device
[1135618.307472] usbcore: registered new interface driver cdc_acm
[1135618.307475] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters

• Connect medtool

to your EverDrive interminal

mode:

./medtool/medtool -p /dev/ttyACM0 -m terminal
Opened serial port /dev/ttyACM0
data out, 4 bytes -->
0x2b 0xd4 0x40 0xbf
<-- data in, 4 bytes
0x5a 0x05 0x25 0x00
core
Creating socket and waiting for connection (minicom -D unix#/tmp/medtool)

Do what it told you and start

minicom

with it connecting to the unix socket formedtool

In the EverDrive menu select

u-boot.bin

hit a button, and then hitstart game

• Wait a little while and you should see u-boot appear on in minicom:

Welcome to minicom 2.10
OPTIONS: I18n
Port unix#/tmp/medtool [?]
Press CTRL-A Z for help on special keys
md
!
a
b
c
U-Boot 2026.01-00675-g9da66c43e96b-dirty (Jun 24 2026 - 20:10:31 +0900)
DRAM: 3.8 MiB
SR is 0x2700
copy from 00000000 to 00398000, 0x27f70 bytes (reloc_off 0x00398000)
copied from 00000000 to 00398000, 0x27f70 bytes (reloc_off 0x00398000)
clearing new bss from 003bd000 to 003bff70
Doing relocation
Relocation point of no return, new SP 0x003368d0, jump to 0x003a0370
Core: 5 devices, 5 uclasses, devicetree: embed
Loading Environment from NVRAM... *** Warning - bad CRC, using default environment
In: serial
Out: serial,vidconsole
Err: serial
Hit any key to stop autoboot: 0
status; 0xa500
status; 0xa500
Loading vmlinux.lz4, 744178 bytes
status; 0xa500
Done
Uncompressed size: 1270696 = 0x1363A8
ELF overwrites reserved memory: 0x00000000 -> 0x0013ff35: -22
new fdt 003392a8
L
s
KLinux version 7.1.0-rc6-00250-g29f5b5b8fc12-dirty (daniel@kinako) (m68k-linux-gcc.br_real (Buildroot -gdb75a8eea0bd) 15.2.0, GNU ld (GNU Binutils) 2.46.0.20260210) #374 Wed Jun 24 22:12:37 JST 2026
Flat model support (C) 1998,1999 Kenneth Albanowski, D. Jeff Dionne
Generic DT Machine (C) 2024 Daniel Palmer <[email protected]>
OF: reserved mem: Reserved memory: No reserved-memory node in the DT
Zone ranges:
DMA [mem 0x0000000000000000-0x00000000003fffff]
Normal empty
Movable zone start for each node
Early memory node ranges
node 0: [mem 0x0000000000000000-0x00000000003fffff]
Initmem setup node 0 [mem 0x0000000000000000-0x00000000003fffff]
Kernel command line: console=ttyVDP0 console=ttyED0 root=/dev/edblk -- smolinit.getty=/dev/ttyED0 smolinit.getty=/dev/ttyVDP0 smolinit.hostname=md
printk: log buffer data + meta data: 4096 + 8704 = 12800 bytes
Dentry cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
Inode-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
Built 1 zonelists, mobility grouping off. Total pages: 1024
mem auto-init: stack:all(zero), heap alloc:off, heap free:off
SLUB: HWalign=16, Order=0-1, MinObjects=0, CPUs=1, Nodes=1
NR_IRQS: 32
clocksource: everdrive-timer: mask: 0xffff max_cycles: 0xffff, max_idle_ns: 29163075000 ns
printk: console [ttyVDP0] enabled
printk: console [ttyED0] enabled
Calibrating delay loop... 0.72 BogoMIPS (lpj=5984)
pid_max: default: 4096 minimum: 301
Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
VFS: Finished mounting rootfs on nullfs
everdrive fifo thread started
Memory: 2532K/4096K available (1002K kernel code, 54K rwdata, 108K rodata, 72K init, 39K bss, 1368K reserved, 0K cma-reserved)
devtmpfs: initialized
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 31854341414376613 ns
clocksource: Switched to clocksource everdrive-timer
workingset: timestamp_bits=30 (anon: 26) max_order=10 bucket_order=0 (anon: 0)
status 0xa500
status 0xa500
status 0xa500
everdrive-blk everdrive-blk@0: Everdrive blk created for m68k.erofs, size is 90112
erofs (device edblk): mounted with root inode @ nid 36.
VFS: Mounted root (erofs filesystem) readonly on device 259:0.
devtmpfs: mounted
VFS: Pivoted into new rootfs
Freeing unused kernel image (initmem) memory: 72K
This architecture does not have kernel memory protection.
Run /sbin/init as init process
smolutils init (Jun 20 2026, 22:01:47)
cmdline args:
smolinit.getty=/dev/ttyED0
Will start getty on TTY /dev/ttyED0
smolinit.getty=/dev/ttyVDP0
Will start getty on TTY /dev/ttyVDP0
smolinit.hostname=md
Hostname will be md
environment variables
HOME=/
TERM=linux
mounting filesystems...
mounted sysfs(sysfs) on /sys
mounted proc(proc) on /proc
mounted tmp(tmpfs) on /tmp
mounted run(tmpfs) on /run
Starting getty on /dev/ttyED0 with shell /bin/smolsh
Starting getty on /dev/ttyVDP0 with shell /bin/smolsh
smolsh / > ls -l
random: crng init done
dr-xr-xr-x 2 root root 447 bin
drwxr-xr-x 2 root root 0 dev
dr-xr-xr-x 61 root root 0 proc
drwxr-xr-x 2 root root 0 run
dr-x------ 2 root root 112 sbin
dr-xr-xr-x 11 root root 0 sys
drwxr-xr-x 2 root root 0 tmp
smolsh / > ps
USER PID CMD
root 1 init
root 2 kthreadd
root 3 pool_workqueue_release
root 4 kworker/R-slub_flushwq
root 5 kworker/0:0-events
root 8 kworker/R-mm_percpu_wq
root 9 everdrive_fifo
root 10 ksoftirqd/0
root 11 pr/ttyED0
root 12 pr/ttyVDP0
root 13 kworker/0:1
root 14 kdevtmpfs
root 15 kworker/R-writeback
root 16 kworker/R-kblockd
root 17 kswapd0
root 18 kworker/u5:0
root 19 kworker/u4:1-ttyED-ttyED
root 20 kworker/u4:2-ttyED-ttyED
root 21 kworker/0:1H-kblockd
root 24 getty
root 25 getty
root 26 smolsh
root 27 smolsh
root 29 kworker/u4:3-ttyED-ttyED
root 30 ps
root 31 kworker/0:0H
root 32 kworker/u4:0-ttyED-ttyED
smolsh / >

Loading and decompressing the kernel will take some time. Wait!

Note that is insanely slow right now. A 12MHz 68000 system I have is way more usable than the megadrive is right now. This needs a bit of optimization. Interacting with the EverDrive fifo is pretty slow.

Well, there is a fancy console using the MegaDrive's video output. It even has nice scrolling..

• In the top right corner there is a green box, t