Kernel Public Heaps

The kernel has 7 heaps for general use by itself, device drivers and file system drivers. They have the following object id mnemonics:

vmkshro

Swappable read-only heap
vmkshrw
Swappable read/write heap
vmkrhro
Resident read-only heap
vmkrhrw
Resident read/write heap
krhro1m
Resident read-only < 1Mb heap
krhrw1m
Resident read/write < 1Mb heap
kbdsym
Resident kernel debugger symbol heap

Not all heaps are always built. Note in particular:

hdbsym is not present under the RETAIL kernel.

vmkshrw is used for the krhro1m, krhrw1m, vmkshrw and vmkshro heaps under the RETAIL kernel.

vmkrhrw is used for both vmkrhrw and vmkrhro under the RETAIL kernel.

Notice that each of the heaps is either resident or swappable.

Each heap is partitioned into blocks.

Swappable heap blocks have an 8 byte prefix followed by the block data.

Resident heap blocks have two forms:

Regular: for smaller allocation. These have a 4 byte prefix.

Attributed or extended: These use a 4 byte prefix and an 8 byte suffix.

---

[Back: Blocking on the Address of a Resource]
[Next: Swappable Heap Blocks]