From d8d686352d57ce31b2b53af86cbd9b98e4c4df4d Mon Sep 17 00:00:00 2001
From: "Chloe M." <chloe@yiffware.org>
Date: Fri, 10 Jul 2026 05:09:53 +0000
Subject: [PATCH] ptos: ke: Add BPAL layer groundwork

Signed-off-by: Chloe M. <chloe@yiffware.org>
---
 service/dev/build.env               |  1 +
 service/dev/bvars.env               |  1 +
 service/ptos/head/ke/bpal.h         | 40 +++++++++++++++++++++++++
 service/ptos/ke/Makefile            |  1 +
 service/ptos/ke/bpal/bpal.c         | 46 +++++++++++++++++++++++++++++
 service/ptos/ke/bpal/proto/limine.c | 28 ++++++++++++++++++
 service/ptos/ke/init.c              |  4 +++
 7 files changed, 121 insertions(+)
 create mode 100644 service/ptos/head/ke/bpal.h
 create mode 100644 service/ptos/ke/bpal/bpal.c
 create mode 100644 service/ptos/ke/bpal/proto/limine.c

diff --git a/service/dev/build.env b/service/dev/build.env
index 1add698..3defa49 100644
--- a/service/dev/build.env
+++ b/service/dev/build.env
@@ -12,6 +12,7 @@
 # Export envs
 export PT_PROJECT_ROOT=$PT_PROJECT_ROOT
 export PT_TARGET_ARCH=$PT_TARGET_ARCH
+export PT_BOOT_PROTO=$PT_BOOT_PROTO
 
 if [ "$PT_BUILD_SOURCED" != "1" ]
 then
diff --git a/service/dev/bvars.env b/service/dev/bvars.env
index fd120b4..af2f356 100644
--- a/service/dev/bvars.env
+++ b/service/dev/bvars.env
@@ -8,3 +8,4 @@
 
 PT_PROJECT_ROOT=$(pwd)
 PT_TARGET_ARCH=amd64
+PT_BOOT_PROTO=limine
diff --git a/service/ptos/head/ke/bpal.h b/service/ptos/head/ke/bpal.h
new file mode 100644
index 0000000..3e715f6
--- /dev/null
+++ b/service/ptos/head/ke/bpal.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Boot protocol abstraction layer
+ * Author:      Chloe M.
+ */
+
+#ifndef _KE_BPAL_H_
+#define _KE_BPAL_H_ 1
+
+#include <ptapi/status.h>
+#include <ptdef.h>
+
+/*
+ * Represents a handle for the boot protocol abstraction
+ * layer containing data filled in by the bootloader.
+ *
+ * @KernelBase: Represents the kernel load base
+ */
+typedef struct {
+    UPTR KernelBase;
+} BPAL_HANDLE;
+
+/*
+ * Initialize the boot protocol abstraction layer
+ */
+VOID KeBpalInit(VOID);
+
+/*
+ * Obtain the BPAL handle
+ *
+ * @Result: Result is written here
+ */
+PT_STATUS KeBpalGetHandle(BPAL_HANDLE *Result);
+
+/* Backend protocol init */
+VOID KeBpalLimineInit(BPAL_HANDLE *Result);
+
+#endif  /* !_KE_BPAL_H_ */
diff --git a/service/ptos/ke/Makefile b/service/ptos/ke/Makefile
index dd8d496..46bd715 100644
--- a/service/ptos/ke/Makefile
+++ b/service/ptos/ke/Makefile
@@ -19,6 +19,7 @@ CFLAGS =							   \
 	-D_KERNEL						   \
 	-DPRINTF_DISABLE_SUPPORT_PTRDIFF_T \
 	-DPRINTF_DISABLE_SUPPORT_FLOAT	   \
+	-D_BOOT_PROTO="\"$(PT_BOOT_PROTO)\"" \
 	-I../xt/flanterm/src			   \
 	-I../head						   \
 	-I../target						   \
diff --git a/service/ptos/ke/bpal/bpal.c b/service/ptos/ke/bpal/bpal.c
new file mode 100644
index 0000000..c32e70e
--- /dev/null
+++ b/service/ptos/ke/bpal/bpal.c
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: BPAL init logic
+ * Author:      Chloe M.
+ */
+
+#include <ke/bpal.h>
+#include <string.h>
+
+#ifndef _BOOT_PROTO
+#error "Boot protocol is undefined"
+#else
+#define BOOT_PROTO _BOOT_PROTO
+#endif  /* !_BOOT_PROTO */
+
+/* Globals */
+static BPAL_HANDLE BpalHandle;
+
+PT_STATUS
+KeBpalGetHandle(BPAL_HANDLE *Result)
+{
+    if (Result == NULL) {
+        return STATUS_INVALID_PARAM;
+    }
+
+    *Result = BpalHandle;
+    return STATUS_SUCCESS;
+}
+
+VOID
+KeBpalInit(VOID)
+{
+    const CHAR *BootProto = BOOT_PROTO;
+
+    switch (*BootProto) {
+    case 'l':
+        if (RtlStrEq(BootProto, "limine")) {
+            KeBpalLimineInit(&BpalHandle);
+            return;
+        }
+    }
+
+    /* TODO: Bugcheck here */
+}
diff --git a/service/ptos/ke/bpal/proto/limine.c b/service/ptos/ke/bpal/proto/limine.c
new file mode 100644
index 0000000..273d1ee
--- /dev/null
+++ b/service/ptos/ke/bpal/proto/limine.c
@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Limine backend
+ * Author:      Chloe M.
+ */
+
+#include <ke/bpal.h>
+#include <lib/limine.h>
+
+/* HHDM request */
+static struct limine_hhdm_response *HHDMResp = NULL;
+static volatile struct limine_hhdm_request HHDMReq = {
+    .id = LIMINE_HHDM_REQUEST_ID,
+    .revision = 0
+};
+
+VOID
+KeBpalLimineInit(BPAL_HANDLE *Result)
+{
+    if (Result == NULL) {
+        return;
+    }
+
+    HHDMResp = HHDMReq.response;
+    Result->KernelBase = HHDMResp->offset;
+}
diff --git a/service/ptos/ke/init.c b/service/ptos/ke/init.c
index 456241f..7567459 100644
--- a/service/ptos/ke/init.c
+++ b/service/ptos/ke/init.c
@@ -7,6 +7,8 @@
  */
 
 #include <ptdef.h>
+#include <ke/bpal.h>
+#include <string.h>
 
 /*
  * Starting here is where the world is brought up and system
@@ -15,4 +17,6 @@
 VOID
 KiKernelInit(VOID)
 {
+    /* Initialize the boot protocol abstraction layer */
+    KeBpalInit();
 }