diff --git a/rust/lib/mammoth/Cargo.toml b/rust/lib/mammoth/Cargo.toml
index 5caf191..4577b56 100644
--- a/rust/lib/mammoth/Cargo.toml
+++ b/rust/lib/mammoth/Cargo.toml
@@ -3,6 +3,9 @@ name = "mammoth"
 version = "0.1.0"
 edition = "2021"
 
+[lib]
+name = "mammoth"
+
 [dependencies]
 
 [build-dependencies]
diff --git a/rust/lib/mammoth/src/bindings.rs b/rust/lib/mammoth/src/bindings.rs
index 24556e8..31568ef 100644
--- a/rust/lib/mammoth/src/bindings.rs
+++ b/rust/lib/mammoth/src/bindings.rs
@@ -1,5 +1,7 @@
 /* automatically generated by rust-bindgen 0.69.4 */
 
+pub type zcap = u64;
+
 pub const _STDINT_H: u32 = 1;
 pub const _FEATURES_H: u32 = 1;
 pub const _ISOC95_SOURCE: u32 = 1;
diff --git a/rust/lib/mammoth/src/lib.rs b/rust/lib/mammoth/src/lib.rs
index be5f1e6..863d06d 100644
--- a/rust/lib/mammoth/src/lib.rs
+++ b/rust/lib/mammoth/src/lib.rs
@@ -8,13 +8,14 @@ use core::panic::PanicInfo;
 
 include!("bindings.rs");
 
-fn syscall<T>(id: u64, req: &T) -> u64 {
+pub fn syscall<T>(id: u64, req: &T) -> u64 {
     unsafe { SysCall1(id, req as *const T as *const c_void) }
 }
 
 #[panic_handler]
 fn panic(_info: &PanicInfo) -> ! {
-    let req = ZProcessExitReq { code: 1 };
+    // Internal error.
+    let req = ZProcessExitReq { code: 0x100 };
     syscall(kZionProcessExit, &req);
     unreachable!()
 }
@@ -26,3 +27,60 @@ pub fn debug(msg: &str) {
     };
     syscall(kZionDebug, &req);
 }
+
+// From /zion/include/ztypes.h
+const Z_INIT_SELF_PROC: u64 = 0x4000_0000;
+const Z_INIT_SELF_VMAS: u64 = 0x4000_0001;
+const Z_INIT_ENDPOINT: u64 = 0x4100_0000;
+
+static mut SELF_PROC_CAP: zcap = 0;
+static mut SELF_VMAS_CAP: zcap = 0;
+static mut INIT_ENDPOINT: zcap = 0;
+
+pub fn parse_init_port(port_cap: zcap) {
+    loop {
+        let mut num_bytes: u64 = 8;
+        let mut init_sig: u64 = 0;
+        let mut caps: [u64; 1] = [0];
+        let mut num_caps: u64 = 1;
+
+        let req = ZPortPollReq {
+            port_cap,
+            num_bytes: &mut num_bytes as *mut u64,
+            data: &mut init_sig as *mut u64 as *mut c_void,
+            caps: &mut caps as *mut u64,
+            num_caps: &mut num_caps as *mut u64,
+        };
+        let resp = syscall(kZionPortPoll, &req);
+        if resp != 0 {
+            break;
+        }
+        unsafe {
+            match init_sig {
+                Z_INIT_SELF_PROC => SELF_PROC_CAP = caps[0],
+                Z_INIT_SELF_VMAS => SELF_VMAS_CAP = caps[0],
+                Z_INIT_ENDPOINT => INIT_ENDPOINT = caps[0],
+                _ => debug("Unknown Cap in Init"),
+            }
+        }
+    }
+}
+
+#[macro_export]
+macro_rules! define_entry {
+    () => {
+        #[no_mangle]
+        pub extern "C" fn _start(init_port: mammoth::zcap) -> ! {
+            extern "C" {
+                fn main() -> z_err_t;
+            }
+            mammoth::parse_init_port(init_port);
+            unsafe {
+                let err = main();
+                let req = mammoth::ZProcessExitReq { code: err };
+                mammoth::syscall(mammoth::kZionProcessExit, &req);
+            }
+            unreachable!()
+        }
+    };
+}
diff --git a/rust/usr/testbed/src/main.rs b/rust/usr/testbed/src/main.rs
index e06f819..53a54fe 100644
--- a/rust/usr/testbed/src/main.rs
+++ b/rust/usr/testbed/src/main.rs
@@ -2,9 +2,13 @@
 #![no_main]
 
 use mammoth::debug;
+use mammoth::define_entry;
+use mammoth::z_err_t;
+
+define_entry!();
 
 #[no_mangle]
-pub extern "C" fn _start() -> ! {
-    debug("Test!");
-    panic!()
+pub extern "C" fn main() -> z_err_t {
+    debug("Testing!");
+    0
 }
diff --git a/sys/yellowstone/hw/gpt.cpp b/sys/yellowstone/hw/gpt.cpp
index 43704cd..a7b2bb3 100644
--- a/sys/yellowstone/hw/gpt.cpp
+++ b/sys/yellowstone/hw/gpt.cpp
@@ -72,9 +72,10 @@ glcr::Status GptReader::ParsePartitionTables() {
   }
   MbrPartition* first_partition =
       reinterpret_cast<MbrPartition*>(lba_1_and_2.vaddr() + 0x1BE);
+
   if (first_partition->boot_indicator != 0) {
-    return glcr::FailedPrecondition(glcr::StrFormat(
-        "Boot indicator set: {}", first_partition->boot_indicator));
+    // FIXME: This shouldn't be set but I can't figure out why it is.
+    dbgln("WARN: Boot indicator set: {}", first_partition->boot_indicator);
   }
   if (first_partition->os_type != 0xEE) {
     return glcr::FailedPrecondition(