gdb for m68k has to be built from source
tar xf gdb-8.1.tar.xz
cd gdb-8.1
mkdir build
cd build
../configure --target=m68k-linux-elf
make -j4
cp gdb/gdb ~/c/gdb-m68k-elf

This has the guy's gdb server as reference
https://github.com/dashxdr/umdkv2


This is what gdbserver claims it can do:

augmented-libraries-svr4-read+;
BreakpointCommands+;
ConditionalBreakpoints+;
ConditionalTracepoints+;
DisconnectedTracing+;
EnableDisableTracepoints+;
exec-events+;
FastTracepoints+;
fork-events+;
hwbreak+;
InstallInTrace+;
multiprocess+;
no-resumed+
PacketSize=3fff;
QAgent+;
QCatchSyscalls+;
QDisableRandomization+;
QEnvironmentHexEncoded+;
QEnvironmentReset+;
QEnvironmentUnset+;
QNonStop+;
QPassSignals+;
QProgramSignals+;
QSetWorkingDir+;
QStartNoAckMode+;
QStartupWithShell+;
QTBuffer:size+;
QThreadEvents+;
qXfer:auxv:read+;
qXfer:exec-file:read+;
qXfer:features:read+;
qXfer:libraries-svr4:read+;
qXfer:osdata:read+;
qXfer:siginfo:read+;
qXfer:siginfo:write+;
qXfer:spu:read+;
qXfer:spu:write+;
qXfer:statictrace:read+;
qXfer:threads:read+;
qXfer:traceframe-info:read+;
StaticTracepoints+;
swbreak+;
tracenz+;
TracepointSource+;
TraceStateVariables+;
vContSupported+;
vfork-events+;