[boot] Load programs in boot, not kernel

Remove ELF and initrd loading from the kernel. The bootloader now loads
the initial programs, as it does with the kernel. Other files that were
in the initrd are now on the ESP, and non-program files are just passed
as modules.

src/boot/loader.h

@@ -5,18 +5,36 @@
 #include <uefi/boot_services.h>
 
 #include "kernel_args.h"
+#include "memory.h"
+#include "types.h"
 
 namespace boot {
+
+namespace fs { class file; }
+
 namespace loader {
 
+/// Load a file from disk into memory.
+/// \arg disk  The opened UEFI filesystem to load from
+/// \arg name  Name of the module (informational only)
+/// \arg path  Path on `disk` of the file to load
+/// \arg type  Memory type to use for allocation
+buffer
+load_file(
+	fs::file &disk,
+	const wchar_t *name,
+	const wchar_t *path,
+	uefi::memory_type type = uefi::memory_type::loader_data);
+
 /// Parse and load an ELF file in memory into a loaded image.
-/// \arg data  The start of the ELF file in memory
-/// \arg size  The size of the ELF file in memory
-/// \arg args  The kernel args, used for modifying page tables
-/// \returns   A descriptor defining the loaded image
-kernel::entrypoint load(
-	const void *data, size_t size,
-	kernel::args::header *args,
+/// \arg program  The program structure to fill
+/// \arg data     Buffer of the ELF file in memory
+/// \arg bs       Boot services
+void
+load_program(
+	kernel::args::program &program,
+	const wchar_t *name,
+	buffer data,
 	uefi::boot_services *bs);
 
 } // namespace loader