Factorize bootstub makefile
Bug: 19708986
This patch aims to remove the huge code duplications in Android.mk and
also add a new kind of bootstub target: ramdump, which is used to boot a
post-crash OS with different memory constraints.
Change-Id: I962b48290994b75a44eb2e47487e1c1a8293f4df
Signed-off-by: Sylvain Chouleur <sylvain.chouleur@intel.com>
diff --git a/2ndbootloader.lds b/2ndbootloader.lds
index 547692d..5189d98 100644
--- a/2ndbootloader.lds
+++ b/2ndbootloader.lds
@@ -3,7 +3,7 @@
ENTRY(_start)
SECTIONS
{
- . = 0x10F00000; /* bootstub entry in DRAM */
+ . = BOOTSTUB_ENTRY; /* bootstub entry in DRAM */
.text.head : {
_head = . ;
*(.text.head)
diff --git a/Android.mk b/Android.mk
index 8a70a83..5dab544 100644
--- a/Android.mk
+++ b/Android.mk
@@ -1,107 +1,28 @@
LOCAL_PATH := $(call my-dir)
-ifeq ($(TARGET_BOARD_PLATFORM),moorefield)
-
-CMDLINE_SIZE ?= 0x400
-BOOTSTUB_SIZE ?= 8192
-
-BOOTSTUB_SRC_FILES := bootstub.c sfi.c ssp-uart.c imr_toc.c spi-uart.c
-BOOTSTUB_SRC_FILES_x86 := head.S e820_bios.S
-
include $(CLEAR_VARS)
-
# bootstub.bin
-LOCAL_SRC_FILES := $(BOOTSTUB_SRC_FILES)
-LOCAL_SRC_FILES_x86 := $(BOOTSTUB_SRC_FILES_x86)
-ANDROID_TOOLCHAIN_FLAGS := -m32 -ffreestanding
-LOCAL_CFLAGS := $(ANDROID_TOOLCHAIN_FLAGS) -Wall -O1 -DCMDLINE_SIZE=${CMDLINE_SIZE}
-LOCAL_MODULE := bootstub.bin
-LOCAL_MODULE_TAGS := optional
-LOCAL_MODULE_PATH := $(PRODUCT_OUT)
-LOCAL_MODULE_CLASS := EXECUTABLES
-LOCAL_FORCE_STATIC_EXECUTABLE := true
+BOOTSTUB_BINARY := bootstub
+BOOTSTUB_AOSP_HEADER_ADDRESS := 0x10007800
+BOOTSTUB_CFLAGS :=
+BOOTSTUB_STACK_OFFSET := 0X10F00000
+BOOTSTUB_ENTRY := 0x1101000
+include $(LOCAL_PATH)/bootstub.mk
-
-include $(BUILD_SYSTEM)/binary.mk
-
-$(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_TARGET_GLOBAL_CFLAGS := $(LOCAL_CFLAGS)
-$(LOCAL_BUILT_MODULE) : PRIVATE_ELF_FILE := $(intermediates)/$(PRIVATE_MODULE).elf
-$(LOCAL_BUILT_MODULE) : PRIVATE_LINK_SCRIPT := $(LOCAL_PATH)/bootstub.lds
-$(LOCAL_BUILT_MODULE) : BOOTSTUB_OBJS := $(patsubst %.c, %.o , $(LOCAL_SRC_FILES))
-$(LOCAL_BUILT_MODULE) : BOOTSTUB_OBJS += $(patsubst %.S, %.o , $(LOCAL_SRC_FILES_x86))
-$(LOCAL_BUILT_MODULE) : BOOTSTUB_OBJS := $(addprefix $(intermediates)/, $(BOOTSTUB_OBJS))
-
-$(LOCAL_BUILT_MODULE): $(all_objects)
- @$(mkdir -p $(dir $@)
- @echo "Generating bootstub.bin: $@"
- $(hide) $(TARGET_LD) \
- -m elf_i386 \
- -T $(PRIVATE_LINK_SCRIPT) \
- $(BOOTSTUB_OBJS) \
- -o $(PRIVATE_ELF_FILE)
- $(hide) $(TARGET_OBJCOPY) -O binary -R .note -R .comment -S $(PRIVATE_ELF_FILE) $@
-
-# Then assemble the final bootstub file
-bootstub_bin := $(PRODUCT_OUT)/bootstub.bin
-bootstub_full := $(PRODUCT_OUT)/bootstub
-
-CHECK_BOOTSTUB_SIZE : $(bootstub_bin)
- $(hide) ACTUAL_SIZE=`$(call get-file-size,$(bootstub_bin))`; \
- if [ "$$ACTUAL_SIZE" -gt "$(BOOTSTUB_SIZE)" ]; then \
- echo "$(bootstub_bin): $$ACTUAL_SIZE exceeds size limit of $(BOOTSTUB_SIZE) bytes, aborting."; \
- exit 1; \
- fi
-
-$(bootstub_full) : CHECK_BOOTSTUB_SIZE
- @echo "Generating bootstub: $@"
- $(hide) cat $(bootstub_bin) /dev/zero | dd bs=$(BOOTSTUB_SIZE) count=1 > $@
-
-# build specific bootstub for GPT/AOSP image support
include $(CLEAR_VARS)
-
# 2ndbootloader.bin
-LOCAL_SRC_FILES := $(BOOTSTUB_SRC_FILES)
-LOCAL_SRC_FILES_x86 := $(BOOTSTUB_SRC_FILES_x86)
-ANDROID_TOOLCHAIN_FLAGS := -m32 -ffreestanding
-LOCAL_CFLAGS := $(ANDROID_TOOLCHAIN_FLAGS) -Wall -O1 -DCMDLINE_SIZE=${CMDLINE_SIZE} -DBUILD_RAMDUMP
-LOCAL_MODULE := 2ndbootloader.bin
-LOCAL_MODULE_TAGS := optional
-LOCAL_MODULE_PATH := $(PRODUCT_OUT)
-LOCAL_MODULE_CLASS := EXECUTABLES
-LOCAL_FORCE_STATIC_EXECUTABLE := true
+BOOTSTUB_BINARY := 2ndbootloader
+BOOTSTUB_AOSP_HEADER_ADDRESS := 0x10007800
+BOOTSTUB_CFLAGS :=
+BOOTSTUB_STACK_OFFSET := 0x10F00000
+BOOTSTUB_ENTRY := 0x10F00000
+include $(LOCAL_PATH)/bootstub.mk
-include $(BUILD_SYSTEM)/binary.mk
-
-$(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_TARGET_GLOBAL_CFLAGS := $(LOCAL_CFLAGS)
-$(LOCAL_BUILT_MODULE) : PRIVATE_ELF_FILE := $(intermediates)/$(PRIVATE_MODULE).elf
-$(LOCAL_BUILT_MODULE) : PRIVATE_LINK_SCRIPT := $(LOCAL_PATH)/2ndbootloader.lds
-$(LOCAL_BUILT_MODULE) : BOOTSTUB_OBJS := $(patsubst %.c, %.o , $(LOCAL_SRC_FILES))
-$(LOCAL_BUILT_MODULE) : BOOTSTUB_OBJS += $(patsubst %.S, %.o , $(LOCAL_SRC_FILES_x86))
-$(LOCAL_BUILT_MODULE) : BOOTSTUB_OBJS := $(addprefix $(intermediates)/, $(BOOTSTUB_OBJS))
-
-$(LOCAL_BUILT_MODULE): $(all_objects)
- @$(mkdir -p $(dir $@)
- @echo "Generating bootstub $@"
- $(hide) $(TARGET_LD) \
- -m elf_i386 \
- -T $(PRIVATE_LINK_SCRIPT) \
- $(BOOTSTUB_OBJS) \
- -o $(PRIVATE_ELF_FILE)
- $(hide) $(TARGET_OBJCOPY) -O binary -R .note -R .comment -S $(PRIVATE_ELF_FILE) $@
-
-# Then assemble the final 2ndbootloader file
-bootstub_aosp_bin := $(PRODUCT_OUT)/2ndbootloader.bin
-bootstub_aosp_full := $(PRODUCT_OUT)/2ndbootloader
-
-CHECK_BOOTSTUB_AOSP_SIZE : $(bootstub_aosp_bin)
- $(hide) ACTUAL_SIZE=`$(call get-file-size,$(bootstub_aosp_bin))`; \
- if [ "$$ACTUAL_SIZE" -gt "$(BOOTSTUB_SIZE)" ]; then \
- echo "$(bootstub_aosp_bin): $$ACTUAL_SIZE exceeds size limit of $(BOOTSTUB_SIZE) bytes, aborting."; \
- exit 1; \
- fi
-
-$(bootstub_aosp_full) : CHECK_BOOTSTUB_AOSP_SIZE
- @echo "Generating bootstub $@"
- $(hide) cat $(bootstub_aosp_bin) /dev/zero | dd bs=$(BOOTSTUB_SIZE) count=1 > $@
-
-endif #($(TARGET_BOARD_PLATFORM),moorefield)
+include $(CLEAR_VARS)
+# bootstub_ramdump.bin
+BOOTSTUB_BINARY := bootstub_ramdump
+BOOTSTUB_AOSP_HEADER_ADDRESS := 0x79000000
+BOOTSTUB_CFLAGS := -DBUILD_RAMDUMP
+BOOTSTUB_STACK_OFFSET := 0x78F00000
+BOOTSTUB_ENTRY := 0x78F00000
+include $(LOCAL_PATH)/bootstub.mk
diff --git a/bootimg.h b/bootimg.h
deleted file mode 100644
index 4c5d00c..0000000
--- a/bootimg.h
+++ /dev/null
@@ -1,96 +0,0 @@
-/*
- * Copyright (C) 2008 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * * Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#ifndef _BOOT_IMAGE_H_
-#define _BOOT_IMAGE_H_
-
-typedef struct boot_img_hdr boot_img_hdr;
-
-#define BOOT_MAGIC "ANDROID!"
-#define BOOT_MAGIC_SIZE 8
-#define BOOT_NAME_SIZE 16
-#define BOOT_ARGS_SIZE 512
-
-struct boot_img_hdr
-{
- unsigned char magic[BOOT_MAGIC_SIZE];
-
- unsigned kernel_size; /* size in bytes */
- unsigned kernel_addr; /* physical load addr */
-
- unsigned ramdisk_size; /* size in bytes */
- unsigned ramdisk_addr; /* physical load addr */
-
- unsigned second_size; /* size in bytes */
- unsigned second_addr; /* physical load addr */
-
- unsigned tags_addr; /* physical addr for kernel tags */
- unsigned page_size; /* flash page size we assume */
- unsigned unused[2]; /* future expansion: should be 0 */
-
- unsigned char name[BOOT_NAME_SIZE]; /* asciiz product name */
- unsigned char cmdline[BOOT_ARGS_SIZE];
-
- unsigned id[8]; /* timestamp / checksum / sha1 / etc */
-};
-
-/*
-** +-----------------+
-** | boot header | 1 page
-** +-----------------+
-** | kernel | n pages
-** +-----------------+
-** | ramdisk | m pages
-** +-----------------+
-** | second stage | o pages
-** +-----------------+
-**
-** n = (kernel_size + page_size - 1) / page_size
-** m = (ramdisk_size + page_size - 1) / page_size
-** o = (second_size + page_size - 1) / page_size
-**
-** 0. all entities are page_size aligned in flash
-** 1. kernel and ramdisk are required (size != 0)
-** 2. second is optional (second_size == 0 -> no second)
-** 3. load each element (kernel, ramdisk, second) at
-** the specified physical address (kernel_addr, etc)
-** 4. prepare tags at tag_addr. kernel_args[] is
-** appended to the kernel commandline in the tags.
-** 5. r0 = 0, r1 = MACHINE_TYPE, r2 = tags_addr
-** 6. if second_size != 0: jump to second_addr
-** else: jump to kernel_addr
-*/
-
-boot_img_hdr *mkbootimg(void *kernel, unsigned kernel_size,
- void *ramdisk, unsigned ramdisk_size,
- void *second, unsigned second_size,
- unsigned page_size,
- unsigned *bootimg_size);
-
-void bootimg_set_cmdline(boot_img_hdr *hdr, const char *cmdline);
-#endif
diff --git a/bootstub.c b/bootstub.c
index c968d04..7c3dc49 100644
--- a/bootstub.c
+++ b/bootstub.c
@@ -1,5 +1,5 @@
/*
- * bootstub 32 bit entry setting routings
+ * bootstub 32 bit entry setting routings
*
* Copyright (C) 2008-2010 Intel Corporation.
* Author: Alek Du <alek.du@intel.com>
@@ -14,7 +14,7 @@
* more details.
*
* You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc.,
+ * this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
@@ -26,7 +26,7 @@
#include "ssp-uart.h"
#include "mb.h"
#include "sfi.h"
-#include "bootimg.h"
+#include <bootimg.h>
#include <stdint.h>
#include <stddef.h>
@@ -84,14 +84,14 @@
char *xs = s;
size_t _count = count / 4;
unsigned long _c = c << 24 | c << 16 | c << 8 | c;
-
+
while (_count--) {
*(long *)xs = _c;
xs += 4;
}
count %= 4;
while (count--)
- *xs++ = c;
+ *xs++ = c;
return s;
}
@@ -150,19 +150,21 @@
{
void *cmdline = (void *)BOOT_CMDLINE_OFFSET;
struct boot_img_hdr *aosp = (struct boot_img_hdr *)AOSP_HEADER_ADDRESS;
- size_t cmdline_len;
+ size_t cmdline_len, extra_cmdline_len;
u8 *initramfs, *ptr;
if (is_image_aosp(aosp->magic)) {
ptr = (u8*)aosp->kernel_addr;
cmdline_len = strnlen((const char *)aosp->cmdline, sizeof(aosp->cmdline));
+ extra_cmdline_len = strnlen((const char *)aosp->extra_cmdline, sizeof(aosp->extra_cmdline));
/*
- * Copy the command line to be after bootparams so that it won't be
- * overwritten by the kernel executable.
+ * Copy the command + extra command line to be after bootparams
+ * so that it won't be overwritten by the kernel executable.
*/
- memset(cmdline, 0, sizeof(aosp->cmdline));
+ memset(cmdline, 0, sizeof(aosp->cmdline) + sizeof(aosp->extra_cmdline));
memcpy(cmdline, (const void *)aosp->cmdline, cmdline_len);
+ memcpy(cmdline + cmdline_len, (const void *)aosp->extra_cmdline, extra_cmdline_len);
bp->hdr.ramdisk_size = aosp->ramdisk_size;
@@ -184,6 +186,7 @@
bp->hdr.cmd_line_ptr = BOOT_CMDLINE_OFFSET;
bp->hdr.cmdline_size = cmdline_len;
+#ifndef BUILD_RAMDUMP
bp->hdr.ramdisk_image = (bp->alt_mem_k*1024 - bp->hdr.ramdisk_size) & 0xFFFFF000;
if (*initramfs) {
@@ -192,6 +195,9 @@
} else {
bs_printk("Won't relocate initramfs, are you in SLE?\n");
}
+#else
+ bp->hdr.ramdisk_image = (u32) initramfs;
+#endif
while (1){
if (*(u32 *)ptr == SETUP_SIGNATURE && *(u32 *)(ptr+4) == 0)
@@ -468,7 +474,8 @@
int nr_entries;
if (is_image_aosp(aosp->magic)) {
- sh = (struct setup_header *)((unsigned int)aosp->kernel_addr + 0x1F1);
+ sh = (struct setup_header *)((unsigned int)aosp->kernel_addr + \
+ (unsigned int)offsetof(struct boot_params,hdr));
/* disable the bs_printk through SPI/UART */
*(int *)SPI_UART_SUPPRESSION = 1;
*(int *)SPI_TYPE = SPI_2;
diff --git a/bootstub.h b/bootstub.h
index a109c09..799c1b3 100644
--- a/bootstub.h
+++ b/bootstub.h
@@ -1,4 +1,4 @@
-/* define bootstub constrains here, like memory map etc.
+/* define bootstub constrains here, like memory map etc.
*/
#ifndef _BOOT_STUB_HEAD
@@ -25,7 +25,6 @@
#define BZIMAGE_SIZE_OFFSET (CMDLINE_OFFSET + CMDLINE_SIZE)
#define INITRD_SIZE_OFFSET (BZIMAGE_SIZE_OFFSET + 4)
#define SPI_UART_SUPPRESSION (INITRD_SIZE_OFFSET + 4)
-#define AOSP_HEADER_ADDRESS 0x10007800
#define SPI_TYPE (SPI_UART_SUPPRESSION + 4) /*0:SPI0 1:SPI1*/
#define SPI_0 0
@@ -39,7 +38,7 @@
#define XEN_SIZE_OFFSET (SEC_PLAT_SVCS_SIZE_OFFSET + 4)
#define BOOTSTUB_OFFSET (BASE_ADDRESS + 0x1000)
-#define STACK_OFFSET 0x10f00000
+
#define BZIMAGE_OFFSET (BASE_ADDRESS + 0x3000)
#define SETUP_HEADER_OFFSET (BZIMAGE_OFFSET + 0x1F1)
diff --git a/bootstub.lds b/bootstub.lds
deleted file mode 100644
index 80c8771..0000000
--- a/bootstub.lds
+++ /dev/null
@@ -1,37 +0,0 @@
-OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
-OUTPUT_ARCH(i386)
-ENTRY(_start)
-SECTIONS
-{
- . = 0x1101000; /* bootstub entry in DRAM */
- .text.head : {
- _head = . ;
- *(.text.head)
- _ehead = . ;
- }
- .text : {
- _text = .; /* Text */
- *(.text)
- *(.text.*)
- _etext = . ;
- }
- .rodata : {
- _rodata = . ;
- *(.rodata) /* read-only data */
- *(.rodata.*)
- _erodata = . ;
- }
- .data : {
- _data = . ;
- *(.data)
- *(.data.*)
- _edata = . ;
- }
- .bss : {
- _bss = . ;
- *(.bss)
- *(.bss.*)
- *(COMMON)
- _end = . ;
- }
-}
diff --git a/bootstub.mk b/bootstub.mk
new file mode 100644
index 0000000..56adcfe
--- /dev/null
+++ b/bootstub.mk
@@ -0,0 +1,60 @@
+CMDLINE_SIZE ?= 0x400
+BOOTSTUB_SIZE ?= 8192
+
+BOOTSTUB_SRC_FILES := bootstub.c sfi.c ssp-uart.c imr_toc.c spi-uart.c
+BOOTSTUB_SRC_FILES_x86 := head.S e820_bios.S
+
+ifeq ($(TARGET_IS_64_BIT),true)
+BOOTSTUB_2ND_ARCH_VAR_PREFIX := $(TARGET_2ND_ARCH_VAR_PREFIX)
+else
+BOOTSTUB_2ND_ARCH_VAR_PREFIX :=
+endif
+
+LOCAL_SRC_FILES := $(BOOTSTUB_SRC_FILES)
+LOCAL_SRC_FILES_x86 := $(BOOTSTUB_SRC_FILES_x86)
+ANDROID_TOOLCHAIN_FLAGS := -m32 -ffreestanding
+LOCAL_CFLAGS := $(ANDROID_TOOLCHAIN_FLAGS) -Wall -O1 -DCMDLINE_SIZE=${CMDLINE_SIZE} -DAOSP_HEADER_ADDRESS=$(BOOTSTUB_AOSP_HEADER_ADDRESS) $(BOOTSTUB_CFLAGS)
+LOCAL_ASFLAGS := -DSTACK_OFFSET=$(BOOTSTUB_STACK_OFFSET)
+LOCAL_C_INCLUDES = system/core/mkbootimg
+LOCAL_MODULE := $(BOOTSTUB_BINARY).bin
+LOCAL_MODULE_TAGS := optional
+LOCAL_MULTILIB := 32
+LOCAL_MODULE_PATH := $(PRODUCT_OUT)
+LOCAL_MODULE_CLASS := EXECUTABLES
+LOCAL_FORCE_STATIC_EXECUTABLE := true
+LOCAL_2ND_ARCH_VAR_PREFIX := $(BOOTSTUB_2ND_ARCH_VAR_PREFIX)
+
+include $(BUILD_SYSTEM)/binary.mk
+
+$(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_TARGET_GLOBAL_CFLAGS := $(LOCAL_CFLAGS)
+$(LOCAL_BUILT_MODULE) : PRIVATE_ELF_FILE := $(intermediates)/$(PRIVATE_MODULE).elf
+$(LOCAL_BUILT_MODULE) : PRIVATE_LINK_SCRIPT := $(LOCAL_PATH)/2ndbootloader.lds
+$(LOCAL_BUILT_MODULE) : BOOTSTUB_OBJS := $(patsubst %.c, %.o , $(LOCAL_SRC_FILES))
+$(LOCAL_BUILT_MODULE) : BOOTSTUB_OBJS += $(patsubst %.S, %.o , $(LOCAL_SRC_FILES_x86))
+$(LOCAL_BUILT_MODULE) : BOOTSTUB_OBJS := $(addprefix $(intermediates)/, $(BOOTSTUB_OBJS))
+$(LOCAL_BUILT_MODULE) : BOOTSTUB_ENTRY := $(BOOTSTUB_ENTRY)
+
+$(LOCAL_BUILT_MODULE): $(all_objects)
+ $(hide) mkdir -p $(dir $@)
+ @echo "Generating bootstub.bin: $@"
+ $(hide) $(TARGET_LD) \
+ -m elf_i386 \
+ -T $(PRIVATE_LINK_SCRIPT) --defsym=BOOTSTUB_ENTRY=$(BOOTSTUB_ENTRY) \
+ $(BOOTSTUB_OBJS) \
+ -o $(PRIVATE_ELF_FILE)
+ $(hide) $(TARGET_OBJCOPY) -O binary -R .note -R .comment -S $(PRIVATE_ELF_FILE) $@
+
+# Then assemble the final bootstub file
+
+bootstub_full := $(PRODUCT_OUT)/$(BOOTSTUB_BINARY)
+$(BOOTSTUB_BINARY)_CHECK_BOOTSTUB_SIZE : $(LOCAL_BUILT_MODULE)
+ $(hide) ACTUAL_SIZE=`$(call get-file-size,$<)`; \
+ if [ "$$ACTUAL_SIZE" -gt "$(BOOTSTUB_SIZE)" ]; then \
+ echo "$<: $$ACTUAL_SIZE exceeds size limit of $(BOOTSTUB_SIZE) bytes, aborting."; \
+ exit 1; \
+ fi
+
+$(bootstub_full) : $(LOCAL_BUILT_MODULE) $(BOOTSTUB_BINARY)_CHECK_BOOTSTUB_SIZE
+ @echo "Generating bootstub: $@"
+ $(hide) cat $< /dev/zero | dd bs=$(BOOTSTUB_SIZE) count=1 > $@
+
