explain some differences from the previous project

README.md

@@ -13,6 +13,26 @@ will be custom integration and other hardening features. The glibc support will
 be limited to replacing the malloc implementation because musl is a much more
 robust and cleaner base to build on and can cover the same use cases.
 
+This allocator is intended as a successor to a previous implementation based on
+extending OpenBSD malloc with various additional security features. It's still
+heavily based on the OpenBSD malloc design, albeit with only a few bits of the
+original code. The main differences in the design are that it's solely focused
+on hardening rather than finding bugs, uses finer-grained size classes based on
+jemalloc with slab sizes going beyond 4k, it doesn't rely on the kernel having
+fine-grained mmap randomization and it only targets 64-bit to make aggressive
+use of the large address space. There are lots of smaller differences in the
+implementation approach. It incorporates the previous extensions made to
+OpenBSD malloc including adding padding to allocations for canaries (distinct
+from the current OpenBSD malloc canaries), write-after-free detection tied to
+the existing clearing on free, queues alongside the existing randomized arrays
+for quarantining allocations and proper double-free detection for quarantined
+allocations. The per-size-class memory regions with their own random bases were
+loosely inspired by the size and type-based partitioning in PartitionAlloc. The
+planned changes to OpenBSD malloc ended up being too extensive and invasive so
+this project was started as a fresh implementation better able to accomplish
+the goals. For 32-bit, a port of OpenBSD malloc with small extensions can be
+used instead as this allocator fundamentally doesn't support that environment.
+
 # Dependencies
 
 Debian stable determines the most ancient set of supported dependencies: