From 13acb13c8f02aa004ae3182524f91e412496adfd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Kr=C3=B6ning?=
 <martin.kroening@eonerc.rwth-aachen.de>
Date: Sat, 16 Nov 2024 12:28:59 +0100
Subject: [PATCH] refactor(multiboot): use shared `Fdt` builder
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Signed-off-by: Martin Kröning <martin.kroening@eonerc.rwth-aachen.de>
---
 src/arch/x86_64/multiboot.rs | 32 ++++++--------------------------
 src/fdt.rs                   | 29 +++++++++++++++++++++++++++++
 src/main.rs                  |  2 +-
 3 files changed, 36 insertions(+), 27 deletions(-)

diff --git a/src/arch/x86_64/multiboot.rs b/src/arch/x86_64/multiboot.rs
index 5e83136..a97f3a8 100644
--- a/src/arch/x86_64/multiboot.rs
+++ b/src/arch/x86_64/multiboot.rs
@@ -1,4 +1,3 @@
-use alloc::format;
 use core::ptr::write_bytes;
 use core::{mem, ptr, slice};
 
@@ -8,14 +7,15 @@ use hermit_entry::boot_info::{
 };
 use hermit_entry::elf::LoadedKernel;
 use log::info;
-use multiboot::information::{MemoryManagement, MemoryType, Multiboot, PAddr};
+use multiboot::information::{MemoryManagement, Multiboot, PAddr};
 use sptr::Strict;
-use vm_fdt::{FdtWriter, FdtWriterResult};
+use vm_fdt::FdtWriterResult;
 use x86_64::structures::paging::{PageSize, PageTableFlags, Size2MiB, Size4KiB};
 
 use super::paging;
 use super::physicalmem::PhysAlloc;
 use crate::arch::x86_64::{KERNEL_STACK_SIZE, SERIAL_IO_PORT};
+use crate::fdt::Fdt;
 use crate::BootInfoExt;
 
 extern "C" {
@@ -55,36 +55,16 @@ impl DeviceTree {
 		let mut mem = Mem;
 		let multiboot = unsafe { Multiboot::from_ptr(mb_info as u64, &mut mem).unwrap() };
 
-		let all_regions = multiboot
+		let memory_regions = multiboot
 			.memory_regions()
 			.expect("Could not find a memory map in the Multiboot information");
-		let ram_regions = all_regions.filter(|m| m.memory_type() == MemoryType::Available);
 
-		let mut fdt = FdtWriter::new()?;
-
-		let root_node = fdt.begin_node("")?;
-		fdt.property_string("compatible", "linux,dummy-virt")?;
-		fdt.property_u32("#address-cells", 0x2)?;
-		fdt.property_u32("#size-cells", 0x2)?;
+		let mut fdt = Fdt::new("multiboot")?.memory_regions(memory_regions)?;
 
 		if let Some(cmdline) = multiboot.command_line() {
-			let chosen_node = fdt.begin_node("chosen")?;
-			fdt.property_string("bootargs", cmdline)?;
-			fdt.end_node(chosen_node)?;
+			fdt = fdt.bootargs(cmdline)?;
 		}
 
-		for m in ram_regions {
-			let start_address = m.base_address();
-			let length = m.length();
-
-			let memory_node = fdt.begin_node(format!("memory@{:x}", start_address).as_str())?;
-			fdt.property_string("device_type", "memory")?;
-			fdt.property_array_u64("reg", &[start_address, length])?;
-			fdt.end_node(memory_node)?;
-		}
-
-		fdt.end_node(root_node)?;
-
 		let fdt = fdt.finish()?;
 
 		Ok(fdt.leak())
diff --git a/src/fdt.rs b/src/fdt.rs
index b2dc6df..1248b06 100644
--- a/src/fdt.rs
+++ b/src/fdt.rs
@@ -48,6 +48,10 @@ impl<'a> Fdt<'a> {
 		Ok(self)
 	}
 
+	#[cfg_attr(
+		all(target_arch = "x86_64", not(target_os = "uefi"), not(feature = "fc")),
+		expect(unused)
+	)]
 	pub fn rsdp(mut self, rsdp: u64) -> FdtWriterResult<Self> {
 		let rsdp_node = self.writer.begin_node(&format!("hermit,rsdp@{rsdp:x}"))?;
 		self.writer.property_array_u64("reg", &[rsdp, 1])?;
@@ -69,6 +73,31 @@ impl<'a> Fdt<'a> {
 	}
 }
 
+#[cfg(all(target_arch = "x86_64", not(target_os = "uefi"), not(feature = "fc")))]
+mod x86_64 {
+	use multiboot::information::{MemoryMapIter, MemoryType};
+	use vm_fdt::FdtWriterResult;
+
+	impl super::Fdt<'_> {
+		pub fn memory_regions(
+			mut self,
+			memory_regions: MemoryMapIter<'_, '_>,
+		) -> FdtWriterResult<Self> {
+			let memory_regions =
+				memory_regions.filter(|m| m.memory_type() == MemoryType::Available);
+
+			for memory_region in memory_regions {
+				self = self.memory(
+					memory_region.base_address()
+						..memory_region.base_address() + memory_region.length(),
+				)?;
+			}
+
+			Ok(self)
+		}
+	}
+}
+
 #[cfg(target_os = "uefi")]
 mod uefi {
 	use core::fmt;
diff --git a/src/main.rs b/src/main.rs
index a082fcd..89f8d77 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -13,7 +13,7 @@ mod macros;
 
 mod arch;
 mod bump_allocator;
-#[cfg(target_os = "uefi")]
+#[cfg(any(target_os = "uefi", all(target_arch = "x86_64", not(feature = "fc"))))]
 mod fdt;
 mod log;
 mod os;