MAXPHYS in md(4)

[Chris Torek]

>Why?  GEOM modules are written on the assumption that no IO larger
>than MAXPHYS will ever be seen...  They allocate arrays of structures
>or other items based upon MAXPHYS, and will smash the stack/crash//do
>bad things if it receives an IO larger than MAXPHYS...
>
>The change would not break anything that isn't already broken (or
>working by luck)...
>
>Now if you're talking about wanting to increase MAXPHYS, there are many
>threads talking about what needs to be done about it, but that is
>completely different than this issue...

Yes, I was thinking of the latter.  It's not *completely*
different as it would be nice to let devices crank down the I/O
size if they have various address and/or byte-count limits.
(Not that I know of any *modern* devices with such limits.  I
see this is mentioned in old freebsd-arch discussions...)

Chris