diff --git a/experimental/rocm/rocm_device.c b/experimental/rocm/rocm_device.c
index a79438359a2a..e0074f131cf4 100644
--- a/experimental/rocm/rocm_device.c
+++ b/experimental/rocm/rocm_device.c
@@ -258,7 +258,7 @@ static iree_status_t iree_hal_rocm_device_queue_alloca(
     iree_hal_device_t* base_device, iree_hal_queue_affinity_t queue_affinity,
     const iree_hal_semaphore_list_t wait_semaphore_list,
     const iree_hal_semaphore_list_t signal_semaphore_list,
-    iree_hal_allocator_pool_id_t pool_id, iree_hal_buffer_params_t params,
+    iree_hal_allocator_pool_t pool, iree_hal_buffer_params_t params,
     iree_device_size_t allocation_size,
     iree_hal_buffer_t** IREE_RESTRICT out_buffer) {
   // TODO: queue-ordered allocations.
diff --git a/runtime/src/iree/hal/allocator.h b/runtime/src/iree/hal/allocator.h
index c8883e2736fb..4c58fc10f0bc 100644
--- a/runtime/src/iree/hal/allocator.h
+++ b/runtime/src/iree/hal/allocator.h
@@ -39,7 +39,13 @@ typedef uint64_t iree_hal_queue_affinity_t;
 #define IREE_HAL_QUEUE_AFFINITY_ANY ((iree_hal_queue_affinity_t)(-1))
 
 // TBD: placeholder for reserving unique pools.
-typedef uint32_t iree_hal_allocator_pool_id_t;
+// The intent is that semantically meaningful pools can be defined like
+// "transient" "variable" "constant" "external" (matching what we use in the
+// compiler) such that allocators don't need to infer based on usage flags.
+enum iree_hal_allocator_pool_bits_t {
+  IREE_HAL_ALLOCATOR_POOL_DEFAULT = 0u,
+};
+typedef uint32_t iree_hal_allocator_pool_t;
 
 // Parameters defining how a buffer should be allocated.
 //
diff --git a/runtime/src/iree/hal/device.c b/runtime/src/iree/hal/device.c
index 1aa24cbbe07a..27330102a2a4 100644
--- a/runtime/src/iree/hal/device.c
+++ b/runtime/src/iree/hal/device.c
@@ -156,7 +156,7 @@ IREE_API_EXPORT iree_status_t iree_hal_device_queue_alloca(
     iree_hal_device_t* device, iree_hal_queue_affinity_t queue_affinity,
     const iree_hal_semaphore_list_t wait_semaphore_list,
     const iree_hal_semaphore_list_t signal_semaphore_list,
-    iree_hal_allocator_pool_id_t pool_id, iree_hal_buffer_params_t params,
+    iree_hal_allocator_pool_t pool, iree_hal_buffer_params_t params,
     iree_device_size_t allocation_size,
     iree_hal_buffer_t** IREE_RESTRICT out_buffer) {
   IREE_ASSERT_ARGUMENT(device);
@@ -170,8 +170,8 @@ IREE_API_EXPORT iree_status_t iree_hal_device_queue_alloca(
   *out_buffer = NULL;
   IREE_TRACE_ZONE_BEGIN(z0);
   iree_status_t status = _VTABLE_DISPATCH(device, queue_alloca)(
-      device, queue_affinity, wait_semaphore_list, signal_semaphore_list,
-      pool_id, params, allocation_size, out_buffer);
+      device, queue_affinity, wait_semaphore_list, signal_semaphore_list, pool,
+      params, allocation_size, out_buffer);
   IREE_TRACE_ZONE_END(z0);
   return status;
 }
diff --git a/runtime/src/iree/hal/device.h b/runtime/src/iree/hal/device.h
index b9ff9304f30e..6c2d581d5ca0 100644
--- a/runtime/src/iree/hal/device.h
+++ b/runtime/src/iree/hal/device.h
@@ -308,7 +308,7 @@ IREE_API_EXPORT iree_status_t iree_hal_device_queue_alloca(
     iree_hal_device_t* device, iree_hal_queue_affinity_t queue_affinity,
     const iree_hal_semaphore_list_t wait_semaphore_list,
     const iree_hal_semaphore_list_t signal_semaphore_list,
-    iree_hal_allocator_pool_id_t pool_id, iree_hal_buffer_params_t params,
+    iree_hal_allocator_pool_t pool, iree_hal_buffer_params_t params,
     iree_device_size_t allocation_size,
     iree_hal_buffer_t** IREE_RESTRICT out_buffer);
 
@@ -453,7 +453,7 @@ typedef struct iree_hal_device_vtable_t {
       iree_hal_device_t* device, iree_hal_queue_affinity_t queue_affinity,
       const iree_hal_semaphore_list_t wait_semaphore_list,
       const iree_hal_semaphore_list_t signal_semaphore_list,
-      iree_hal_allocator_pool_id_t pool_id, iree_hal_buffer_params_t params,
+      iree_hal_allocator_pool_t pool, iree_hal_buffer_params_t params,
       iree_device_size_t allocation_size,
       iree_hal_buffer_t** IREE_RESTRICT out_buffer);
 
diff --git a/runtime/src/iree/hal/drivers/cuda/cuda_device.c b/runtime/src/iree/hal/drivers/cuda/cuda_device.c
index 68c0ed635dea..4ffd897cc8b5 100644
--- a/runtime/src/iree/hal/drivers/cuda/cuda_device.c
+++ b/runtime/src/iree/hal/drivers/cuda/cuda_device.c
@@ -333,7 +333,7 @@ static iree_status_t iree_hal_cuda_device_queue_alloca(
     iree_hal_device_t* base_device, iree_hal_queue_affinity_t queue_affinity,
     const iree_hal_semaphore_list_t wait_semaphore_list,
     const iree_hal_semaphore_list_t signal_semaphore_list,
-    iree_hal_allocator_pool_id_t pool_id, iree_hal_buffer_params_t params,
+    iree_hal_allocator_pool_t pool, iree_hal_buffer_params_t params,
     iree_device_size_t allocation_size,
     iree_hal_buffer_t** IREE_RESTRICT out_buffer) {
   // TODO(benvanik): queue-ordered allocations.
diff --git a/runtime/src/iree/hal/drivers/local_sync/sync_device.c b/runtime/src/iree/hal/drivers/local_sync/sync_device.c
index d5cc8c4121c2..1a222fd6084b 100644
--- a/runtime/src/iree/hal/drivers/local_sync/sync_device.c
+++ b/runtime/src/iree/hal/drivers/local_sync/sync_device.c
@@ -273,7 +273,7 @@ static iree_status_t iree_hal_sync_device_queue_alloca(
     iree_hal_device_t* base_device, iree_hal_queue_affinity_t queue_affinity,
     const iree_hal_semaphore_list_t wait_semaphore_list,
     const iree_hal_semaphore_list_t signal_semaphore_list,
-    iree_hal_allocator_pool_id_t pool_id, iree_hal_buffer_params_t params,
+    iree_hal_allocator_pool_t pool, iree_hal_buffer_params_t params,
     iree_device_size_t allocation_size,
     iree_hal_buffer_t** IREE_RESTRICT out_buffer) {
   // TODO(benvanik): queue-ordered allocations.
diff --git a/runtime/src/iree/hal/drivers/local_task/task_device.c b/runtime/src/iree/hal/drivers/local_task/task_device.c
index 5e9d94eadda9..c30645770cb4 100644
--- a/runtime/src/iree/hal/drivers/local_task/task_device.c
+++ b/runtime/src/iree/hal/drivers/local_task/task_device.c
@@ -323,7 +323,7 @@ static iree_status_t iree_hal_task_device_queue_alloca(
     iree_hal_device_t* base_device, iree_hal_queue_affinity_t queue_affinity,
     const iree_hal_semaphore_list_t wait_semaphore_list,
     const iree_hal_semaphore_list_t signal_semaphore_list,
-    iree_hal_allocator_pool_id_t pool_id, iree_hal_buffer_params_t params,
+    iree_hal_allocator_pool_t pool, iree_hal_buffer_params_t params,
     iree_device_size_t allocation_size,
     iree_hal_buffer_t** IREE_RESTRICT out_buffer) {
   // TODO(benvanik): queue-ordered allocations.
diff --git a/runtime/src/iree/hal/drivers/vulkan/vulkan_device.cc b/runtime/src/iree/hal/drivers/vulkan/vulkan_device.cc
index e614a42ee3b0..118ebac1533a 100644
--- a/runtime/src/iree/hal/drivers/vulkan/vulkan_device.cc
+++ b/runtime/src/iree/hal/drivers/vulkan/vulkan_device.cc
@@ -1080,7 +1080,7 @@ static iree_status_t iree_hal_vulkan_device_queue_alloca(
     iree_hal_device_t* base_device, iree_hal_queue_affinity_t queue_affinity,
     const iree_hal_semaphore_list_t wait_semaphore_list,
     const iree_hal_semaphore_list_t signal_semaphore_list,
-    iree_hal_allocator_pool_id_t pool_id, iree_hal_buffer_params_t params,
+    iree_hal_allocator_pool_t pool, iree_hal_buffer_params_t params,
     iree_device_size_t allocation_size,
     iree_hal_buffer_t** IREE_RESTRICT out_buffer) {
   // TODO(benvanik): queue-ordered allocations.
diff --git a/runtime/src/iree/modules/hal/module.c b/runtime/src/iree/modules/hal/module.c
index 395d0566d611..8871249be761 100644
--- a/runtime/src/iree/modules/hal/module.c
+++ b/runtime/src/iree/modules/hal/module.c
@@ -854,7 +854,7 @@ IREE_VM_ABI_EXPORT(iree_hal_module_device_queue_alloca,  //
       (iree_hal_queue_affinity_t)args->i1;
   iree_hal_fence_t* wait_fence = iree_hal_fence_deref(args->r2);
   iree_hal_fence_t* signal_fence = iree_hal_fence_deref(args->r3);
-  iree_hal_allocator_pool_id_t pool_id = (iree_hal_allocator_pool_id_t)args->i4;
+  iree_hal_allocator_pool_t pool = (iree_hal_allocator_pool_t)args->i4;
   iree_hal_memory_type_t memory_types = (iree_hal_memory_type_t)args->i5;
   iree_hal_buffer_usage_t buffer_usage = (iree_hal_buffer_usage_t)args->i6;
   iree_device_size_t allocation_size = iree_hal_cast_device_size(args->i7);
@@ -866,7 +866,7 @@ IREE_VM_ABI_EXPORT(iree_hal_module_device_queue_alloca,  //
   iree_hal_buffer_t* buffer = NULL;
   IREE_RETURN_IF_ERROR(iree_hal_device_queue_alloca(
       device, queue_affinity, iree_hal_fence_semaphore_list(wait_fence),
-      iree_hal_fence_semaphore_list(signal_fence), pool_id, params,
+      iree_hal_fence_semaphore_list(signal_fence), pool, params,
       allocation_size, &buffer));
 
   rets->r0 = iree_hal_buffer_move_ref(buffer);