Re: Tonight's tradeoff

On Thu, 7 Mar 2024 16:02:45 -0500, Robert Finch <robfi680@gmail.com>
wrote:

A page marked RWE=000 is an unusable page. Perhaps to signal bad memory. Or perhaps as a hidden data page full of comments or remarks. If its not readable-writeable or executable what is it? Nothing should be able to access it, except maybe the machine/debug operating mode.

The ability to change (at least data) pages between "untouchable" and
RW is required for MMU assisted incremental GC.  If the GC also
handles code, then it must be able to mark pages executable as well.
If an "untouchable" page can't be manipulated by user software, then
you've disallowed an entire class of GC systems.