Re: Just my 2 penny worth..

[Julian Reschke-FJR010 <Julian_Reschke-FJR010@email.mot.com>]

Stephen.Usher@earth.ox.ac.uk%INTERNET wrote:
>...
> And on the subject of using the old disk drivers.. if the system has
> basically been re-initialised with a fully virtual addressing system, the
> old drivers will not be able to interact with the new programs trying to
> access them as the new programs would be passing virtual addresses and
> wouldn't have direct access to the driver anyway as it would not appear in
> their memory map anyway.

This can be handled by the virtual memory code which can control the
Rwabs calls. See Outside.



> 
> >> Senario 2..
> >>
> >>      Program attempts to access a DMA device in a way in which it has
> >>      been deemed illegal (eg. a virus tries to write to the boot sector
> >>      of a SCSI disk).
> >>
> >>      The kernel gets the DMA request.. sees that it's something which is
> >>      not permitted and does a pre-defined action.. either giving the
> >>      program an error or killing it.
> >
> >This can be done just now - every disk acces goes through the kernel (how
> >about XHDI? The kernel could easily wrap these) - no need for modifications
> >on the driver side.
> 
> See above.. the old driver couldn't really work properly as it would be in a
> ROM-TOS environment which would disappear from under it once MiNT got into
> the full swing of things, unless you made some unholy kludge. The only way
> to use it would be to somehow reload the driver after MiNT had started,
> giving it special privilages to access the hardware and locking the pages
> into contiguous memory, making the virtual addresses the same as the
> physical.. and even then I'm not sure how other programs could access it
> other than by the kernel forwarding on the requests. Remember, by this time,
> all you know about TOS memory management has totally gone out of the window,
> you're in a totally different mode of operation, ALL programs but the OS are
> seeing an illusion of what the system state is.
> 
> The only way around the kludge would be to ask one of the developers nicely
> if we could include a modified version of their code into the kernel, or
> borrow drivers from elsewhere or write them from scratch.
> 
> As for the XHDI interface, there's no problem with giving the user processes
> the same interface as that all helps with compatibility with old programs.
> 
> >Actually, HDDriver can do just this: write-protect the boot/rootsectors.
> 
> Maybe, but a user program can always subvert this by going straight for the
> hardware and doing all its disk access directly.

No, they can't if you turn on the latest MiNT security features.

Regards, jr