From d79b33f5be78839a0b6b9b616d5fbb33ea8838c7 Mon Sep 17 00:00:00 2001
From: "Chloe M." <chloe@mensia.org>
Date: Wed, 15 Jul 2026 23:10:04 +0000
Subject: [PATCH] ptos/amd64: mp: Add MP bootstrap stub / groundwork

Signed-off-by: Chloe M. <chloe@mensia.org>
---
 service/ptos/arch/amd64/cpu/mp.c | 82 ++++++++++++++++++++++++++++++++
 service/ptos/head/hal/mp.h       | 20 ++++++++
 service/ptos/ke/init.c           |  4 ++
 3 files changed, 106 insertions(+)
 create mode 100644 service/ptos/arch/amd64/cpu/mp.c
 create mode 100644 service/ptos/head/hal/mp.h

diff --git a/service/ptos/arch/amd64/cpu/mp.c b/service/ptos/arch/amd64/cpu/mp.c
new file mode 100644
index 0000000..eb78e24
--- /dev/null
+++ b/service/ptos/arch/amd64/cpu/mp.c
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Multi-processing
+ * Author:      Chloe M.
+ */
+
+#include <ptdef.h>
+#include <ex/trace.h>
+#include <drivers/acpi/acpi.h>
+#include <drivers/acpi/tables.h>
+#include <ke/bugcheck.h>
+#include <machine/lapic.h>
+
+/* Max processors to bootstrap */
+#define CPU_MAX 64
+
+#define DTRACE(Fmt, ...) \
+    TRACE("[ MP ]: " Fmt, ##__VA_ARGS__)
+
+/* Number of processor cores */
+static USHORT CoreCount = 0;
+
+/*
+ * Bootstrap a single core
+ *
+ * @LocalApic: Local APIC descriptor of core to bootstrap
+ *
+ * TODO: This is a stub
+ */
+static VOID
+BootstrapCore(ACPI_LOCAL_APIC *LocalApic)
+{
+    if (LocalApic == NULL) {
+        return;
+    }
+
+    ++CoreCount;
+}
+
+static VOID
+MpBootstrap(VOID)
+{
+    ACPI_MADT *Madt;
+    UCHAR *Ptr, *EndPtr;
+    ACPI_APIC_HEADER *Header;
+    ACPI_LOCAL_APIC *LocalApic;
+
+    Madt = AcpiQuery("APIC");
+    if (Madt == NULL) {
+        KeBugCheck(
+            BUGCHECK_MISC,
+            "unable to detect ACPI MADT table\n"
+        );
+    }
+
+    Ptr = PTR_OFFSET(Madt, sizeof(ACPI_MADT));
+    EndPtr = PTR_OFFSET(Ptr, Madt->Header.Length);
+
+    /* Iterate every interrupt controller entry */
+    while (Ptr < EndPtr) {
+        Header = (ACPI_APIC_HEADER *)Ptr;
+
+        switch (Header->Type) {
+        case APIC_TYPE_LOCAL_APIC:
+            LocalApic = (ACPI_LOCAL_APIC *)Header;
+            BootstrapCore(LocalApic);
+            break;
+        }
+
+        Ptr = PTR_OFFSET(Ptr, Header->Length);
+    }
+
+    DTRACE("detected %d processor core(s)\n", CoreCount);
+}
+
+VOID
+HalMpBootstrap(VOID)
+{
+    MpBootstrap();
+}
diff --git a/service/ptos/head/hal/mp.h b/service/ptos/head/hal/mp.h
new file mode 100644
index 0000000..8aef8b5
--- /dev/null
+++ b/service/ptos/head/hal/mp.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Multi-processing HAL layer
+ * Author:      Chloe M.
+ */
+
+#ifndef _HAL_MP_H_
+#define _HAL_MP_H_ 1
+
+#include <ptdef.h>
+
+/*
+ * Bring up all application processors on a multicore
+ * system.
+ */
+VOID HalMpBootstrap(VOID);
+
+#endif  /* !_HAL_MP_H_ */
diff --git a/service/ptos/ke/init.c b/service/ptos/ke/init.c
index b93e238..2a42434 100644
--- a/service/ptos/ke/init.c
+++ b/service/ptos/ke/init.c
@@ -21,6 +21,7 @@
 #include <hal/serial.h>
 #include <hal/thread.h>
 #include <hal/kpcr.h>
+#include <hal/mp.h>
 #include <drivers/bootvid/fbio.h>
 #include <drivers/acpi/acpi.h>
 #include <string.h>
@@ -144,6 +145,9 @@ KiKernelInit(VOID)
     /* Initialize the root process */
     InitializeRootProcess();
 
+    /* Bootstrap all other cores */
+    HalMpBootstrap();
+
     /* Prime the scheduler timer */
     HalPrimeThreadTimer(SCHED_MIN_QUANTUM);