From 090e4148b8596674fde96e52842740556ad9750d Mon Sep 17 00:00:00 2001
From: Gabriel <gabscoarnec@gmail.com>
Date: Sat, 15 Feb 2025 22:18:49 +0100
Subject: [PATCH] core: Reserve physical page 0

In the kernel's early stages we access physical memory identity-mapped, so it's not very good for us to allocate that frame and then try to use it.
---
 core/src/pmm.zig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/core/src/pmm.zig b/core/src/pmm.zig
index 6d0fd5a..3a195b9 100644
--- a/core/src/pmm.zig
+++ b/core/src/pmm.zig
@@ -99,5 +99,8 @@ pub fn initializeFrameAllocator(tag: *easyboot.multiboot_tag_mmap_t) !FrameAlloc
     const frames_to_lock = try std.math.divCeil(usize, bitmap_size, platform.PAGE_SIZE);
     try lockFrames(&allocator, @intFromPtr(bitmap_base_address), frames_to_lock);
 
+    // Avoid causing trouble.
+    try lockFrame(&allocator, 0);
+
     return allocator;
 }