1 files changed, 101 insertions, 0 deletions
diff --git a/crates/kernel/src/lib.rs b/crates/kernel/src/lib.rs
new file mode 100644
index 0000000..eff6d36
--- /dev/null
+++ b/crates/kernel/src/lib.rs
@@ -0,0 +1,101 @@
+//! The static library that forms the core of the kernel.
+#![no_std]
+
+use crate::arch::{sleep_forever, PAGE_SIZE};
+use log::{debug, info, warn};
+use vernos_alloc_physmem_free_list::FreeListAllocator;
+use vernos_device_tree::FlattenedDeviceTree;
+use vernos_utils::dbg;
+
+#[cfg(target_os = "none")]
+mod panic;
+
+pub mod arch;
+
+/// The entrypoint to the kernel. This should be executed by hart0 alone. It performs some early
+/// boot tasks, then wakes up any other harts.
+///
+/// # Safety
+///
+/// - The `device_tree` pointer must be a valid pointer into physical memory. See
+///   `device_tree::FlattenedDeviceTree::from_ptr` for the precise requirements.
+/// - This must be called in supervisor mode with paging and traps disabled, but with all traps
+///   delegated to supervisor mode.
+/// - Any other harts must not be running concurrently with us. TODO: Define their state.
+#[no_mangle]
+pub unsafe extern "C" fn hart0_boot(device_tree: *const u8) -> ! {
+    // Set up the logger.
+    //
+    // TODO: This should really be named something better than console.
+    // console::init();
+
+    // Parse the DeviceTree.
+    let flattened_device_tree =
+        unsafe { FlattenedDeviceTree::from_ptr(device_tree) }.expect("invalid DeviceTree");
+
+    // Find the available physical memory areas and initialize the physical memory
+    // free-list.
+    let mut physical_memory_free_list = FreeListAllocator::<PAGE_SIZE>::new();
+    dbg!(physical_memory_free_list);
+
+    /*
+    flattened_device_tree
+        .for_each_node(|node| {
+            if node.is_unit(&["", "memory"]) {
+                // Get the memory ranges.
+                let Some(reg) = node.get_reg_usize() else {
+                    warn!("{}reg was not valid", node.name());
+                    return Ok(());
+                };
+
+                for (addr, size) in reg {
+                    physical_memory_free_list.add_range(addr..addr + size);
+                }
+            }
+            Ok(())
+        })
+        .unwrap_or_else(|err| void::unreachable(err));
+
+    // Log the physical memory we found.
+    debug!(
+        "found {} usable regions of physical memory{}",
+        physical_memory_free_list.len(),
+        if physical_memory_free_list.is_empty() {
+            ""
+        } else {
+            ":"
+        }
+    );
+    for region in physical_memory_free_list.drain() {
+        debug!(
+            "{:p}..{:p} ({} byte{})",
+            region.start as *const u8,
+            region.end as *const u8,
+            region.len(),
+            if region.len() == 1 { "" } else { "s" }
+        )
+    }
+    */
+
+    // After this point, everything else is for debugging.
+    #[cfg(target_arch = "riscv64")]
+    {
+        flattened_device_tree
+            .for_each_node(|node| {
+                if node.is_unit(&["", "cpus"]) {
+                    if let Some(timebase_frequency) = node.get_prop_u32("timebase-frequency") {
+                        // SAFETY: Other harts are not concurrently running, so they can't be
+                        // concurrently accessing or modifying this.
+                        unsafe {
+                            vernos_driver_riscv_timer::TIMEBASE_FREQUENCY = timebase_frequency;
+                        }
+                    }
+                }
+                Ok(())
+            })
+            .unwrap_or_else(|err| void::unreachable(err));
+        arch::interrupts::example_timer();
+    }
+    info!("sleeping forever...");
+    sleep_forever();
+}