blk@mitre.org (Brian L. Kahn) (03/23/90)
I am interested in running DOS and standard programs on a Virtual DOS system using a 386 base. The goal is a sort of augmented and paranoid access control over the disk (and maybe network); rather than go into that let me say for argument that I want detailed statistics on any and all peripherals while running standard programs such as Lotus, Word, WordPerfect, dBase, etc. I want to tally all writes to screen memory, all disk accesses, any bypass of BIOS such as controller or timer reprogramming, and so on. Can anyone offer insight into such an enterprise? Yes I know that performance will suffer, and a drop of 50% is OK! I have read about one or two virtual DOS's whose main goal is to switch between environs, but I want to stick in a review mechanism between the software (DOS + application) and the hardware. ADthanksVANCE -- B< Brian Kahn blk@security.mitre.org "may the farce be with you"
dhinds@portia.Stanford.EDU (David Hinds) (03/23/90)
In article <BLK.90Mar22132317@vanity.mitre.org>, blk@mitre.org (Brian L. Kahn) writes: > > I am interested in running DOS and standard programs on a Virtual DOS > system using a 386 base. The goal is a sort of augmented and paranoid > access control over the disk (and maybe network); rather than go into > that let me say for argument that I want detailed statistics on any > and all peripherals while running standard programs such as Lotus, > Word, WordPerfect, dBase, etc. I want to tally all writes to screen > memory, all disk accesses, any bypass of BIOS such as controller or > timer reprogramming, and so on. > > Can anyone offer insight into such an enterprise? Yes I know that > performance will suffer, and a drop of 50% is OK! I have read about > one or two virtual DOS's whose main goal is to switch between > environs, but I want to stick in a review mechanism between the > software (DOS + application) and the hardware. > It sounds like you would be better off writing your own virtual 86 supervisor. This is easier than it sounds, actually. I have a book on the 80386 ("80386 Technical Reference", I don't remember the author) that gives the skeleton of a supervisor for DOS in an appendix. There isn't much to this - it just sets up all the protected-mode interrupt handlers to bounce a virtual-mode interrupt back to the appropriate virtual-mode DOS or BIOS handler. You would need to set up a bunch of counters, and just add a little bit of code to these handlers to keep track of each call before passing control on to DOS. You can also trap I/O instructions in a similar fashion - I don't know if the example does this, though. The review mechanism should be absolutely, positively transparent. -David Hinds dhinds@popserver.stanford.edu