posixcompat: sbrk: add comment about using a memobj_append.
@@ -90,6 +90,7 @@ void *sbrk(intptr_t increment)
errval_t err;
size_t orig_offset;
+ /* we're using an append memobj for sbrk */
if (!memobj) { // Initialize
err = vspace_map_append_nomalloc(&base, &memobj_, &vregion_,
SBRK_REGION_BYTES, NULL,
