Re: oskit-mach/libstore breakage

[Thomas Bushnell, BSG]

Roland McGrath <roland@frob.com> writes:

> > libstore uses device_map with size and offset being null.  
> 
> Urmph.  To my mind, this just illustrates that the current io_map interface
> model is really wrong and that an io_map call that takes offset and size
> parameters is the way to go (as is already my plan for large-file mapping).

There is just no effecient way to implement that on Mach.  If you
expect to allow users to give their own offsets, then the filesystem
will have to manage N different memory objects, and the won't be able
to share.

Worse yet, if users give non-page-aligned offsets, then you have to
play copy-and-invalidate games with the data.

Thomas