usb target disk mode equivalent on running system

Is there anyway that you can expose local partition or disk image through your computer usb to another computer to appear like external drive on mac/linux/bsd system ?

I'm trying to play with something like kernel development and I need one system for开发者_JAVA百科 compiling and other for restarting/testing.

With USB: Not a chance. USB is unidirectional, and your development system has no way of emulating a mass storage device, or any kind of other USB device.

With Firewire: Theoretically. (This is what Apple's target disk mode is using.) However, I can't find a readily available solution for that.

I'd advice you to try either virtualization or network boot. VirtualBox is free and open software, and has a variety of command line options, which means it can be scripted. Network boot takes a little effort to set up, but can work really well.

Yet another option, is to use a minimal Linux distribution as a bootstrap which sets up the environment you want, and then uses kexec to launch your kernel, possibly with GRUB as an intermediary step.

What kind of kernel are you fiddling with? If it's your own code, will the kernel operate in real or protected mode? Do you strictly need disk access, or do you just want to boot the actual kernel?