perf(kernel): kernel static all-zero -> .bss (image 812K -> 173K): domain::Slot (repr(u8) Empty=0) for tables, zero generation counters, core ids by position, pool/platform installed at boot; Option-backed Slot under kani (cbmc speed); build fails if .data > 16K

crates/kernel/src/syscall/ipc/endpoint.rs

@@ -148,7 +148,7 @@ impl<P: Platform> Kernel<P> {
             return SyscallOutcome::Complete(SyscallResult::Error(KernelError::EndpointFull));
         }
         if let Some(s) = self.ipc_mut(tid) {
-            s.outgoing = Some(out);
+            s.outgoing.set(out);
         }
         let reason = if is_call {
             BlockReason::Calling(ep)

crates/kernel/src/syscall/ipc/mod.rs

@@ -42,7 +42,7 @@ pub(crate) struct Outgoing {
 /// Per-thread IPC bookkeeping.
 #[derive(Debug, Clone, Copy, Default)]
 pub struct IpcState {
-    pub(crate) outgoing: Option<Outgoing>,
+    pub(crate) outgoing: domain::slot::Slot<Outgoing>,
     /// The caller this thread owes a reply to.
     pub(crate) reply_to: Option<ThreadRef>,
     /// Callers it kept to answer later (`SaveReply`).
@@ -55,7 +55,7 @@ pub(crate) const SAVED: usize = types::bounded::SavedReply::MAX as usize + 1;
 
 impl IpcState {
     pub const EMPTY: Self = Self {
-        outgoing: None,
+        outgoing: domain::slot::Slot::Empty,
         reply_to: None,
         saved: [None; SAVED],
         bound: None,
@@ -73,7 +73,7 @@ impl<P: Platform> Kernel<P> {
 
     pub(crate) fn set_pending_result(&mut self, tid: ThreadId, result: Option<SyscallResult>) {
         if let Some(r) = self.pending_results.get_mut(tid.raw() as usize) {
-            *r = result;
+            *r = result.into();
         }
     }