Comment 6 for bug 579347

more generally implemented, watchpoints could not only be specified with an address offset but also a size in bits or bytes, so that any read/write accesses to arbitrarily large types/data structures could be tracked just by defining the start of the data in memory and its size in bits/bytes.

This would not only facilitate watching statically defined data, but also dynamically created data structures that may simply not be available during the assembly process.

From an implementation point of view, there could be optional callbacks registered for read/writes and if the callbacks pointer is not NULL, it could be invoked in order to trigger the watchpoint

http://www.cs.dal.ca/studentservices/refcards/gdbref.pdf
http://www.delorie.com/gnu/docs/gdb/gdb_30.html
http://www.unknownroad.com/rtfm/gdbtut/gdbwatch.html