EFI: Hand off bootloader log to the kernel.

Eventually, EFI should get support for the debug log ring_buffer
like bios_ia32 has for transparent handoffs, but this preserves
everything except for the pre-start MMU dump, which is an improvement.

Fixes #15455.

src/system/boot/platform/efi/debug.cpp

@@ -10,6 +10,7 @@
 #include <boot/stage2.h>
 #include <boot/stdio.h>
 
+#include "debug.h"
 #include "efi_platform.h"
 #include "serial.h"
 
@@ -70,6 +71,18 @@ panic(const char *format, ...)
 }
 
 
+void
+debug_cleanup(void)
+{
+	gKernelArgs.keep_debug_output_buffer = false;
+	gKernelArgs.debug_output = kernel_args_malloc(sBufferPosition);
+	if (gKernelArgs.debug_output != NULL) {
+		memcpy(gKernelArgs.debug_output, sBuffer, sBufferPosition);
+		gKernelArgs.debug_size = sBufferPosition;
+	}
+}
+
+
 char*
 platform_debug_get_log_buffer(size_t *_size)
 {

src/system/boot/platform/efi/debug.h

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2021, Haiku, Inc. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef DEBUG_H
+#define DEBUG_H
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void debug_cleanup(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif	// DEBUG_H

src/system/boot/platform/efi/start.cpp

@@ -25,6 +25,7 @@
 #include "acpi.h"
 #include "console.h"
 #include "cpu.h"
+#include "debug.h"
 #ifdef _BOOT_FDT_SUPPORT
 #include "dtb.h"
 #endif
@@ -186,6 +187,8 @@ platform_start_kernel(void)
 	dprintf("  data: %#" B_PRIx64 ", %#" B_PRIx64 "\n", dataRegion.start, dataRegion.size);
 	dprintf("  entry: %#lx\n", kernelEntry);
 
+	debug_cleanup();
+
 	arch_mmu_init();
 	convert_kernel_args();