Generating kernel_arg sizes per version

generate_kernel_arg_sizes.sh

	rm -f $(1)
	TEMPFILE=$(mktemp)
	OUTFILE=$(mktemp)
	GENERATORFILE=$(mktemp)
	COUNTER=1
	CONTINUE=1
	cat  <<EOF > $GENERATORFILE
#include <kernel_args.h>
#if CURRENT_KERNEL_ARGS_VERSION > MAX_KERNEL_ARGS_VERSION
#error "Unsupported version"
#endif
#include <stdio.h>
int main()
{
	printf("\t%lu,\n", sizeof(kernel_args));
	return 0;
}
EOF
	echo 'size_t kernel_arg_sizes[] = {' > $OUTFILE
	while [ $CONTINUE -eq 1 ]; do
		$(CC) -o $TEMPFILE $GENERATORFILE -DCURRENT_KERNEL_ARGS_VERSION=$COUNTER
		if [ $? -eq 0 ]; then
			$TEMPFILE >> $OUTFILE
			COUNTER=$((COUNTER + 1))
		else
			CONTINUE=0
		fi
	done
	echo '};' >> $OUTFILE
	rm -f $TEMPFILE $GENERATORFILE
	mv $OUTFILE $(1)

kernel_args-version.patch

From 0967250bbdfc95b3a17bc8b73d1c01e025d4b8b3 Mon Sep 17 00:00:00 2001
From: Jessica Hamilton <jessica.l.hamilton@gmail.com>
Date: Thu, 15 Sep 2016 19:29:26 +1200
Subject: [PATCH] kernel_args: support multiple versions

---
 headers/private/kernel/boot/kernel_args.h          |  8 ++++-
 .../boot/platform/bios_ia32/platform_kernel_args.h |  3 +-
 .../boot/platform/efi/platform_kernel_args.h       |  7 +++-
 src/system/kernel/arch/x86/arch_platform.cpp       | 38 ++++++++++++----------
 4 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/headers/private/kernel/boot/kernel_args.h b/headers/private/kernel/boot/kernel_args.h
index 9a6a455..45b07af 100644
--- a/headers/private/kernel/boot/kernel_args.h
+++ b/headers/private/kernel/boot/kernel_args.h
@@ -21,7 +21,10 @@
 #include <util/FixedWidthPointer.h>


-#define CURRENT_KERNEL_ARGS_VERSION    1
+#ifndef CURRENT_KERNEL_ARGS_VERSION
+#define CURRENT_KERNEL_ARGS_VERSION    2
+#endif
+#define MAX_KERNEL_ARGS_VERSION 2
 #define MAX_KERNEL_ARGS_RANGE          20

 // names of common boot_volume fields
@@ -33,6 +36,9 @@
 #define BOOT_VOLUME_PARTITION_OFFSET   "partition offset"
 #define BOOT_VOLUME_DISK_IDENTIFIER            "disk identifier"

+// needed for versioning the kernel_args
+extern size_t kernel_arg_sizes[MAX_KERNEL_ARGS_VERSION];
+
 // boot methods
 enum {
        BOOT_METHOD_HARD_DISK   = 0,
diff --git a/headers/private/kernel/boot/platform/bios_ia32/platform_kernel_args.h b/headers/private/kernel/boot/platform/bios_ia32/platform_kernel_args.h
index 7464468..df422b0 100644
--- a/headers/private/kernel/boot/platform/bios_ia32/platform_kernel_args.h
+++ b/headers/private/kernel/boot/platform/bios_ia32/platform_kernel_args.h
@@ -30,8 +30,9 @@ typedef struct {
                // this does not contain the boot drive

        apm_info        apm;
-
+#if CURRENT_KERNEL_ARGS_VERSION >= 2
        FixedWidthPointer<void> acpi_root;
+#endif
 } _PACKED platform_kernel_args;

 #endif /* KERNEL_BOOT_PLATFORM_BIOS_IA32_KERNEL_ARGS_H */
diff --git a/headers/private/kernel/boot/platform/efi/platform_kernel_args.h b/headers/private/kernel/boot/platform/efi/platform_kernel_args.h
index 2ded98e..e7ee0cc 100644
--- a/headers/private/kernel/boot/platform/efi/platform_kernel_args.h
+++ b/headers/private/kernel/boot/platform/efi/platform_kernel_args.h
@@ -10,6 +10,10 @@
 #      error This file is included from <boot/kernel_args.h> only
 #endif

+#if CURRENT_KERNEL_ARGS_VERSION < 2
+#error "require kernel args version > 2"
+#endif
+
 // currently the EFI loader pretends to be the bios_ia32 platform.
 // not quite right, as the kernel needs to be aware of efi runtime services

@@ -41,8 +45,9 @@ typedef struct {
        // seems to be ignored entirely?

        apm_info        apm;
-
+#if CURRENT_KERNEL_ARGS_VERSION >= 2
        FixedWidthPointer<void> acpi_root;
+#endif
 } _PACKED platform_kernel_args;


diff --git a/src/system/kernel/arch/x86/arch_platform.cpp b/src/system/kernel/arch/x86/arch_platform.cpp
index a1f3226..6c231e4 100644
--- a/src/system/kernel/arch/x86/arch_platform.cpp
+++ b/src/system/kernel/arch/x86/arch_platform.cpp
@@ -7,30 +7,32 @@
  *             Axel Dörfler, axeld@pinc-software.de
  */

-
-#include <arch/platform.h>
-#include <apm.h>
-#include <boot_item.h>
-#include <boot/stage2.h>
-
-
-status_t
+
+#include <arch/platform.h>
+#include <apm.h>
+#include <boot_item.h>
+#include <boot/stage2.h>
+
+
+status_t
 arch_platform_init(struct kernel_args *args)
 {
        return B_OK;
 }


-status_t
-arch_platform_init_post_vm(struct kernel_args *args)
-{
-       // Now we can add boot items; pass on the ACPI root pointer
-       add_boot_item("ACPI_ROOT_POINTER",
-               args->platform_args.acpi_root.Pointer(), sizeof(void*));
-
-       return B_OK;
-}
-
+status_t
+arch_platform_init_post_vm(struct kernel_args *args)
+{
+       if (args->version >= 2) {
+               // Now we can add boot items; pass on the ACPI root pointer
+               add_boot_item("ACPI_ROOT_POINTER",
+                       args->platform_args.acpi_root.Pointer(), sizeof(void*));
+       }
+
+       return B_OK;
+}
+

 status_t
 arch_platform_init_post_thread(struct kernel_args *args)
--
2.5.0