Allow debug option to be communicated at boot

src/boot/guids.inc

@@ -6,4 +6,6 @@ GUID(0x964e5b22,0x6459,0x11d2,0x8e,0x39,0x00,0xa0,0xc9,0x69,0x72,0x3b, guid_simp
 GUID(0x09576e91,0x6d3f,0x11d2,0x8e,0x39,0x00,0xa0,0xc9,0x69,0x72,0x3b, guid_device_path);
 GUID(0x8b843e20,0x8132,0x4852,0x90,0xcc,0x55,0x1a,0x4e,0x4a,0x7f,0x1c, guid_device_path_to_text);
 
+GUID(0x10d0669c,0x9ec6,0x4268,0xbc,0x48,0xff,0x74,0x75,0x21,0xfe,0x07, guid_popcorn_vendor);
+
 // vim: ft=c

src/boot/loader.cpp

@@ -143,7 +143,7 @@ loader_load_elf(
 		header.machine != 0x3e)
 		CHECK_EFI_STATUS_OR_RETURN(EFI_LOAD_ERROR, L"ELF load error: wrong machine architecture");
 
-	con_debug(L"ELF is valid, entrypoint %lu\r\n", header.entrypoint);
+	con_debug(L"ELF is valid, entrypoint %lx\r\n", header.entrypoint);
 
 	data->kernel_entry = (void *)header.entrypoint;
 

src/boot/main.cpp

@@ -5,7 +5,7 @@
 
 #include "console.h"
 #include "guids.h"
-#include "kernel_data.h"
+#include "kernel_args.h"
 #include "loader.h"
 #include "memory.h"
 #include "utility.h"
@@ -34,7 +34,51 @@ struct kernel_header {
 };
 #pragma pack(pop)
 
-using kernel_entry = void (*)(popcorn_data *);
+using kernel_entry = void (*)(kernel_args *);
+
+static void
+type_to_wchar(wchar_t *into, uint32_t type)
+{
+	for (int j=0; j<4; ++j)
+		into[j] = static_cast<wchar_t>(reinterpret_cast<char *>(&type)[j]);
+}
+
+EFI_STATUS
+detect_debug_mode(EFI_RUNTIME_SERVICES *run, kernel_args *header) {
+	wchar_t var_name[] = L"debug";
+
+	EFI_STATUS status;
+	uint8_t debug = 0;
+	UINTN var_size = sizeof(debug);
+
+#ifdef __POPCORN_SET_DEBUG_UEFI_VAR__
+	debug = __POPCORN_SET_DEBUG_UEFI_VAR__;
+	uint32_t attrs =
+		EFI_VARIABLE_NON_VOLATILE |
+		EFI_VARIABLE_BOOTSERVICE_ACCESS |
+		EFI_VARIABLE_RUNTIME_ACCESS;
+	status = run->SetVariable(
+			var_name,
+			&guid_popcorn_vendor,
+			attrs,
+			var_size,
+			&debug);
+	CHECK_EFI_STATUS_OR_RETURN(status, "detect_debug_mode::SetVariable");
+#endif
+
+	status = run->GetVariable(
+			var_name,
+			&guid_popcorn_vendor,
+			nullptr,
+			&var_size,
+			&debug);
+	CHECK_EFI_STATUS_OR_RETURN(status, "detect_debug_mode::GetVariable");
+
+	if (debug)
+		header->flags |= POPCORN_FLAG_DEBUG;
+
+	return EFI_SUCCESS;
+}
 
 extern "C" EFI_STATUS
 efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE *system_table)
@@ -73,14 +117,13 @@ efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE *system_table)
 	status = memory_get_map_length(bootsvc, &data_length);
 	CHECK_EFI_STATUS_OR_FAIL(status);
 
-	size_t header_size = sizeof(popcorn_data);
-	const size_t header_align = alignof(popcorn_data);
+	size_t header_size = sizeof(kernel_args);
+	const size_t header_align = alignof(kernel_args);
 	if (header_size % header_align)
 		header_size += header_align - (header_size % header_align);
 
 	data_length += header_size;
 
-
 	// Load the kernel image from disk and check it
 	//
 	console::print(L"Loading kernel into memory...\r\n");
@@ -111,12 +154,12 @@ efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE *system_table)
 
 	// Set up the kernel data pages to pass to the kernel
 	//
-	struct popcorn_data *data_header = (struct popcorn_data *)load.data; 
+	struct kernel_args *data_header = (struct kernel_args *)load.data;
 	memory_mark_pointer_fixup((void **)&data_header);
 
 	data_header->magic = DATA_HEADER_MAGIC;
 	data_header->version = DATA_HEADER_VERSION;
-	data_header->length = sizeof(struct popcorn_data);
+	data_header->length = sizeof(struct kernel_args);
 
 	data_header->scratch_pages = SCRATCH_PAGES;
 	data_header->flags = 0;
@@ -168,6 +211,8 @@ efi_main(EFI_HANDLE image_handle, EFI_SYSTEM_TABLE *system_table)
 	data_header->memory_map_length = map.length;
 	data_header->memory_map_desc_size = map.size;
 
+	detect_debug_mode(runsvc, data_header);
+
 	// bootsvc->Stall(5000000);
 
 	status = bootsvc->ExitBootServices(image_handle, map.key);

src/include/kernel_args.h

@@ -7,8 +7,10 @@
 #define DATA_HEADER_MAGIC     0x600dda7a
 #define DATA_HEADER_VERSION   1
 
+#define POPCORN_FLAG_DEBUG    0x00000001
+
 #pragma pack(push, 1)
-struct popcorn_data {
+struct kernel_args {
 	uint32_t magic;
 	uint16_t version;
 	uint16_t length;

src/kernel/assert.cpp

@@ -18,9 +18,3 @@ __kernel_assert(const char *file, unsigned line, const char *message)
 	__asm__ ( "int $0e7h" );
 	while (1) __asm__ ("hlt");
 }
-
-extern "C" [[noreturn]] void
-__assert_fail(const char *message, const char *file, unsigned int line, const char *function)
-{
-	__kernel_assert(file, line, message);
-}

src/kernel/main.cpp

@@ -11,7 +11,7 @@
 #include "gdt.h"
 #include "interrupts.h"
 #include "io.h"
-#include "kernel_data.h"
+#include "kernel_args.h"
 #include "log.h"
 #include "page_manager.h"
 #include "scheduler.h"
@@ -20,7 +20,7 @@
 #include "syscall.h"
 
 extern "C" {
-	void kernel_main(popcorn_data *header);
+	void kernel_main(kernel_args *header);
 	void *__bss_start, *__bss_end;
 }
 
@@ -39,28 +39,21 @@ init_console()
 
 	log::init(cons);
 	log::enable(logs::apic, log::level::info);
-	log::enable(logs::device, log::level::info);
+	log::enable(logs::device, log::level::debug);
+	log::enable(logs::paging, log::level::info);
 
 	log::enable(logs::driver, log::level::debug);
 	log::enable(logs::memory, log::level::debug);
 	log::enable(logs::fs, log::level::debug);
 	log::enable(logs::task, log::level::debug);
 	log::enable(logs::boot, log::level::debug);
-	log::enable(logs::paging, log::level::debug);
 }
 
 void
-kernel_main(popcorn_data *header)
+kernel_main(kernel_args *header)
 {
-#ifdef DEBUG
-	// Run `waf configure --debug` to enable compiling with DEBUG turned on.
-	// Then attach to QEMU's gdb server and `set waiting = false` to start
-	// the kernel. This compensates for GDB's poor handling of QEMU going
-	// through the x86 PC startup and switching to 64 bit mode when you
-	// attach to qemu with the -S option.
-	bool waiting = true;
+	bool waiting = header && (header->flags && POPCORN_FLAG_DEBUG);
 	while (waiting);
-#endif
 
 	kutil::assert_set_callback(__kernel_assert);
 

src/libraries/kutil/frame_allocator.cpp

@@ -1,5 +1,3 @@
-#include <algorithm>
-
 #include "kutil/frame_allocator.h"
 
 namespace kutil {
@@ -81,7 +79,7 @@ frame_allocator::allocate(size_t count, uintptr_t *address)
 
 	auto *first = m_free.front();
 
-	unsigned n = std::min(count, static_cast<size_t>(first->count));
+	unsigned n = count < first->count ? count : first->count;
 	*address = first->address;
 
 	if (count >= first->count) {