From 704fd15f7b210307f0ff5c5b15a6a6a41b4829b5 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Tue, 15 Mar 2022 23:58:37 -0400
Subject: [PATCH] Get memory map; remove heap

---
 src/hel/heap.d            | 19 ----------------
 src/hel/hel.d             | 46 ++++++++++++++++++++++++++++++++++-----
 src/kernel/hos/bootinfo.d |  5 +++--
 3 files changed, 43 insertions(+), 27 deletions(-)
 delete mode 100644 src/hel/heap.d

diff --git a/src/hel/heap.d b/src/hel/heap.d
deleted file mode 100644
index b0b5fe2..0000000
--- a/src/hel/heap.d
+++ /dev/null
@@ -1,19 +0,0 @@
-private __gshared align(4096) ubyte[512 * 1024] g_heap;
-private __gshared size_t g_heap_index;
-
-ubyte * heap_base()
-{
-    return &g_heap[g_heap_index];
-}
-
-size_t heap_free()
-{
-    return g_heap.sizeof - g_heap_index;
-}
-
-ubyte * heap_consume(size_t size)
-{
-    ubyte * rv = &g_heap[g_heap_index];
-    g_heap_index += (size + 4095u) & 0xFFFFFFFFFFFFF000u;
-    return rv;
-}
diff --git a/src/hel/hel.d b/src/hel/hel.d
index 75503b2..78d03af 100644
--- a/src/hel/hel.d
+++ b/src/hel/hel.d
@@ -1,10 +1,11 @@
 import uefi;
 import output;
-import heap;
 import hos.bootinfo;
 
 __gshared EFI_SYSTEM_TABLE * st;
-__gshared BootInfo * bootinfo;
+__gshared BootInfo bootinfo;
+__gshared ubyte[512 * 1024] scratch;
+__gshared UINTN memory_map_key;
 
 private void wait_key()
 {
@@ -30,9 +31,9 @@ private bool in_qemu()
 private bool set_graphics_mode()
 {
     uint max_horizontal_resolution = in_qemu() ? 1920u : 0xFFFFFFFFu;
-    UINTN buffer_size = heap_free();
+    UINTN buffer_size = scratch.sizeof;
     EFI_GUID gop_guid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
-    EFI_HANDLE * handles = cast(EFI_HANDLE *)heap_base();
+    EFI_HANDLE * handles = cast(EFI_HANDLE *)&scratch;
     EFI_STATUS status = st.BootServices.LocateHandle(ByProtocol,
             &gop_guid, null, &buffer_size, handles);
     if (status != EFI_SUCCESS)
@@ -84,6 +85,39 @@ private bool set_graphics_mode()
     return true;
 }
 
+private bool get_memory_map()
+{
+    UINTN memory_map_size = scratch.sizeof;
+    UINTN descriptor_size;
+    UINT32 descriptor_version;
+    UINTN status = st.BootServices.GetMemoryMap(
+            &memory_map_size,
+            cast(EFI_MEMORY_DESCRIPTOR *)&scratch,
+            &memory_map_key,
+            &descriptor_size,
+            &descriptor_version);
+    if (status != EFI_SUCCESS)
+    {
+        return false;
+    }
+    size_t n_entries = memory_map_size / descriptor_size;
+    size_t di;
+    for (size_t i = 0u; i < n_entries; i++)
+    {
+        EFI_MEMORY_DESCRIPTOR * descriptor = cast(EFI_MEMORY_DESCRIPTOR *)&scratch[i * descriptor_size];
+        if ((descriptor.Type == EfiConventionalMemory) ||
+            (descriptor.Type == EfiBootServicesCode) ||
+            (descriptor.Type == EfiBootServicesData))
+        {
+            bootinfo.memory_map[di].base = cast(void *)descriptor.PhysicalStart;
+            bootinfo.memory_map[di].size = descriptor.NumberOfPages * 4096u;
+            di++;
+        }
+    }
+    bootinfo.memory_map_count = di;
+    return true;
+}
+
 extern (C) EFI_STATUS efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE * st)
 {
     .st = st;
@@ -93,14 +127,14 @@ extern (C) EFI_STATUS efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE * st)
     writeln("HOS EFI loader");
     writeln("Firmware vendor: '%S', version: 0x%x", st.FirmwareVendor, st.FirmwareVendor);
 
-    bootinfo = cast(BootInfo *)heap_consume(BootInfo.sizeof);
-
     if (!set_graphics_mode())
     {
         wait_key();
         return EFI_SUCCESS;
     }
 
+    get_memory_map();
+
     wait_key();
 
     return EFI_SUCCESS;
diff --git a/src/kernel/hos/bootinfo.d b/src/kernel/hos/bootinfo.d
index 68cda2d..8da62cf 100644
--- a/src/kernel/hos/bootinfo.d
+++ b/src/kernel/hos/bootinfo.d
@@ -13,7 +13,8 @@ struct BootInfo
         uint stride;
         uint format;
     }
+
     Framebuffer fb;
-    MemoryRegion * memory_map;
-    uint memory_map_size;
+    MemoryRegion[500] memory_map;
+    size_t memory_map_count;
 }