bastion: initial implementation

ready project skeleton
dual-arch build system with Linux-config style configuration
UEFI EFI stub loader (PE32+) for x86_64 and AArch64
ELF64 kernel parser
Temporary framebuffer console
freestanding string and c++ abi stubs

For now, kernel boots, prints banner, memory map and go halt

1 files changed, 29 insertions, 0 deletions

diff --git a/boot/x86_64/entry.cpp b/boot/x86_64/entry.cpp
new file mode 100644
index 0000000..b9f710d
--- /dev/null
+++ b/boot/x86_64/entry.cpp
@@ -0,0 +1,29 @@
+// ============================================================================
+// x86_64/entry.cpp - UEFI entry point for x86_64
+//
+// Kernel entry: extern "C" [[noreturn]] void kernel_main(BootInfo*);
+// ============================================================================
+
+#include <boot/efi.h>
+#include <boot/boot_info.h>
+
+extern bool efi_loader_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE* system_table, BootInfo* boot_info);
+
+static BootInfo g_boot_info{};
+
+typedef void (*KernelEntry)(BootInfo*);
+
+extern "C" EFI_STATUS EFIAPI efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE* system_table) {
+    if (!efi_loader_main(image_handle, system_table, &g_boot_info)) {
+        return EFI_LOAD_ERROR;
+    }
+
+    // Post-ExitBootServices: compute physical entry and jump
+    uint64_t entry_offset = g_boot_info.kernel_entry_point - g_boot_info.kernel_virt_base;
+    uint64_t phys_entry   = g_boot_info.kernel_phys_base + entry_offset;
+
+    auto kernel_entry = reinterpret_cast<KernelEntry>(phys_entry);
+    kernel_entry(&g_boot_info);  // RDI = &g_boot_info (System V ABI)
+
+    for (;;) asm volatile("hlt");
+}