My brain isn't in the right place for SDL hacking right now. It seems pretty doable, but I'm bored. I keep thinking about filesystems, so thats where I'm going to focus my efforts for the moment.
Regardless of whether DOS packets or IO win the day as the filesystem interface of choice, something I am going to need is some sort of virtual disk device so I can use real filesystem under hosted. This idea is the same as what's used in virtualisation software everywhere - you have a big opaque chunk of disk that the virtual machine treats as a real piece of hardware.
This one doesn't look too hard to implement. All devices are roughly the same, so most of what I learned from
tap.device should apply here. The initial goal is to mount a CD-ROM image using
cdrom.handler - only read magic required :)