diff --git a/sys/denali/ahci/ahci_driver.cpp b/sys/denali/ahci/ahci_driver.cpp
index 28bd709..658b9ee 100644
--- a/sys/denali/ahci/ahci_driver.cpp
+++ b/sys/denali/ahci/ahci_driver.cpp
@@ -8,8 +8,6 @@
 
 namespace {
 
-const uint64_t kPciSize = 0x1000;
-
 const uint64_t kGhc_InteruptEnable = 0x2;
 
 void interrupt_thread(void* void_driver) {
@@ -20,18 +18,11 @@ void interrupt_thread(void* void_driver) {
   crash("Driver returned from interrupt loop", glcr::INTERNAL);
 }
 
-PciDeviceHeader* LoadPciDeviceHeader(uint64_t ahci_phys) {
-  MappedMemoryRegion pci_region =
-      MappedMemoryRegion::DirectPhysical(ahci_phys, kPciSize);
-  return reinterpret_cast<PciDeviceHeader*>(pci_region.vaddr());
-}
-
 }  // namespace
 
 glcr::ErrorOr<glcr::UniquePtr<AhciDriver>> AhciDriver::Init(
-    uint64_t ahci_phys) {
-  PciDeviceHeader* header = LoadPciDeviceHeader(ahci_phys);
-  glcr::UniquePtr<AhciDriver> driver(new AhciDriver(header));
+    MappedMemoryRegion pci_region) {
+  glcr::UniquePtr<AhciDriver> driver(new AhciDriver(pci_region));
   // RET_ERR(driver->LoadCapabilities());
   RET_ERR(driver->LoadHbaRegisters());
   RET_ERR(driver->LoadDevices());
diff --git a/sys/denali/ahci/ahci_driver.h b/sys/denali/ahci/ahci_driver.h
index 936f6dd..410ee5d 100644
--- a/sys/denali/ahci/ahci_driver.h
+++ b/sys/denali/ahci/ahci_driver.h
@@ -10,7 +10,8 @@
 
 class AhciDriver {
  public:
-  static glcr::ErrorOr<glcr::UniquePtr<AhciDriver>> Init(uint64_t ahci_phys);
+  static glcr::ErrorOr<glcr::UniquePtr<AhciDriver>> Init(
+      MappedMemoryRegion ahci_phys);
   glcr::ErrorCode RegisterIrq();
 
   void InterruptLoop();
@@ -21,6 +22,7 @@ class AhciDriver {
   void DumpPorts();
 
  private:
+  MappedMemoryRegion pci_region_;
   PciDeviceHeader* pci_device_header_ = nullptr;
   MappedMemoryRegion ahci_region_;
   AhciHba* ahci_hba_ = nullptr;
@@ -38,6 +40,8 @@ class AhciDriver {
   glcr::ErrorCode LoadHbaRegisters();
   glcr::ErrorCode LoadDevices();
 
-  AhciDriver(PciDeviceHeader* device_header)
-      : pci_device_header_(device_header) {}
+  AhciDriver(MappedMemoryRegion pci_region)
+      : pci_region_(pci_region),
+        pci_device_header_(
+            reinterpret_cast<PciDeviceHeader*>(pci_region_.vaddr())) {}
 };
diff --git a/sys/denali/denali.cpp b/sys/denali/denali.cpp
index f3e75f7..106020d 100644
--- a/sys/denali/denali.cpp
+++ b/sys/denali/denali.cpp
@@ -5,6 +5,7 @@
 #include <mammoth/port_client.h>
 #include <stdint.h>
 #include <yellowstone.h>
+#include <yellowstone_stub.h>
 
 #include "ahci/ahci_driver.h"
 #include "denali_server.h"
@@ -13,18 +14,10 @@ uint64_t main(uint64_t init_port_cap) {
   check(ParseInitPort(init_port_cap));
   glcr::UniquePtr<EndpointClient> yellowstone =
       EndpointClient::AdoptEndpoint(gInitEndpointCap);
-  YellowstoneGetReq ahci_req{
-      .type = kYellowstoneGetAhci,
-  };
-  auto resp_or =
-      yellowstone->CallEndpoint<YellowstoneGetReq, YellowstoneGetAhciResp>(
-          ahci_req);
-  if (!resp_or.ok()) {
-    check(resp_or.error());
-  }
 
-  uint64_t ahci_addr = resp_or.value().ahci_phys_offset;
-  ASSIGN_OR_RETURN(auto driver, AhciDriver::Init(ahci_addr));
+  YellowstoneStub stub(gInitEndpointCap);
+  ASSIGN_OR_RETURN(MappedMemoryRegion ahci_region, stub.GetAhciConfig());
+  ASSIGN_OR_RETURN(auto driver, AhciDriver::Init(ahci_region));
 
   YellowstoneGetReq req{
       .type = kYellowstoneGetRegistration,
diff --git a/sys/yellowstone/CMakeLists.txt b/sys/yellowstone/CMakeLists.txt
index fe1082f..ac35d6c 100644
--- a/sys/yellowstone/CMakeLists.txt
+++ b/sys/yellowstone/CMakeLists.txt
@@ -4,7 +4,8 @@ add_executable(yellowstone
   yellowstone.cpp
   yellowstone_server.cpp
   )
- target_include_directories(yellowstone
+
+target_include_directories(yellowstone
    PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
 
 target_link_libraries(yellowstone
@@ -27,6 +28,10 @@ target_include_directories(yellowstone_stub
    PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
    PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/include")
 
+target_link_libraries(yellowstone_stub
+  mammoth
+  )
+
 set_target_properties(yellowstone_stub PROPERTIES
   COMPILE_FLAGS "${CMAKE_CXX_FLAGS} ${BASE_COMPILE_FLAGS}"
   LINK_FLAGS "${CMAKE_EXE_LINK_FLAGS} ${BASE_LINK_FLAGS}"
diff --git a/sys/yellowstone/include/yellowstone_stub.h b/sys/yellowstone/include/yellowstone_stub.h
new file mode 100644
index 0000000..b665c22
--- /dev/null
+++ b/sys/yellowstone/include/yellowstone_stub.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include <mammoth/endpoint_client.h>
+#include <mammoth/memory_region.h>
+#include <ztypes.h>
+
+class YellowstoneStub {
+ public:
+  explicit YellowstoneStub(z_cap_t yellowstone_cap);
+
+  glcr::ErrorOr<MappedMemoryRegion> GetAhciConfig();
+
+ private:
+  glcr::UniquePtr<EndpointClient> yellowstone_stub_;
+};
diff --git a/sys/yellowstone/stub/yellowstone_stub.cpp b/sys/yellowstone/stub/yellowstone_stub.cpp
index 85a0b90..d05ecb7 100644
--- a/sys/yellowstone/stub/yellowstone_stub.cpp
+++ b/sys/yellowstone/stub/yellowstone_stub.cpp
@@ -1,3 +1,23 @@
-// PLACEHOLDER
-#include <stdint.h>
-uint64_t a = 0;
+#include "include/yellowstone_stub.h"
+
+#include "include/yellowstone.h"
+
+namespace {
+
+const uint64_t kPciSize = 0x1000;
+
+}  // namespace
+
+YellowstoneStub::YellowstoneStub(z_cap_t yellowstone_cap)
+    : yellowstone_stub_(EndpointClient::AdoptEndpoint(yellowstone_cap)) {}
+
+glcr::ErrorOr<MappedMemoryRegion> YellowstoneStub::GetAhciConfig() {
+  YellowstoneGetReq req{
+      .type = kYellowstoneGetAhci,
+  };
+  ASSIGN_OR_RETURN(
+      YellowstoneGetAhciResp resp,
+      (yellowstone_stub_
+           ->CallEndpoint<YellowstoneGetReq, YellowstoneGetAhciResp>(req)));
+  return MappedMemoryRegion::DirectPhysical(resp.ahci_phys_offset, kPciSize);
+}