Commit 82782ca7 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'x86-kbuild-for-linus' of...

Merge branch 'x86-kbuild-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-kbuild-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (46 commits)
  x86, boot: add new generated files to the appropriate .gitignore files
  x86, boot: correct the calculation of ZO_INIT_SIZE
  x86-64: align __PHYSICAL_START, remove __KERNEL_ALIGN
  x86, boot: correct sanity checks in boot/compressed/misc.c
  x86: add extension fields for bootloader type and version
  x86, defconfig: update kernel position parameters
  x86, defconfig: update to current, no material changes
  x86: make CONFIG_RELOCATABLE the default
  x86: default CONFIG_PHYSICAL_START and CONFIG_PHYSICAL_ALIGN to 16 MB
  x86: document new bzImage fields
  x86, boot: make kernel_alignment adjustable; new bzImage fields
  x86, boot: remove dead code from boot/compressed/head_*.S
  x86, boot: use LOAD_PHYSICAL_ADDR on 64 bits
  x86, boot: make symbols from the main vmlinux available
  x86, boot: determine compressed code offset at compile time
  x86, boot: use appropriate rep string for move and clear
  x86, boot: zero EFLAGS on 32 bits
  x86, boot: set up the decompression stack as early as possible
  x86, boot: straighten out ranges to copy/zero in compressed/head*.S
  x86, boot: stylistic cleanups for boot/compressed/head_64.S
  ...

Fixed trivial conflict in arch/x86/configs/x86_64_defconfig manually
parents f0d5e12b 6799687a
......@@ -50,6 +50,10 @@ Protocol 2.08: (Kernel 2.6.26) Added crc32 checksum and ELF format
Protocol 2.09: (Kernel 2.6.26) Added a field of 64-bit physical
pointer to single linked list of struct setup_data.
Protocol 2.10: (Kernel 2.6.31) Added a protocol for relaxed alignment
beyond the kernel_alignment added, new init_size and
pref_address fields. Added extended boot loader IDs.
**** MEMORY LAYOUT
The traditional memory map for the kernel loader, used for Image or
......@@ -168,12 +172,13 @@ Offset Proto Name Meaning
021C/4 2.00+ ramdisk_size initrd size (set by boot loader)
0220/4 2.00+ bootsect_kludge DO NOT USE - for bootsect.S use only
0224/2 2.01+ heap_end_ptr Free memory after setup end
0226/2 N/A pad1 Unused
0226/1 2.02+(3 ext_loader_ver Extended boot loader version
0227/1 2.02+(3 ext_loader_type Extended boot loader ID
0228/4 2.02+ cmd_line_ptr 32-bit pointer to the kernel command line
022C/4 2.03+ ramdisk_max Highest legal initrd address
0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel
0234/1 2.05+ relocatable_kernel Whether kernel is relocatable or not
0235/1 N/A pad2 Unused
0235/1 2.10+ min_alignment Minimum alignment, as a power of two
0236/2 N/A pad3 Unused
0238/4 2.06+ cmdline_size Maximum size of the kernel command line
023C/4 2.07+ hardware_subarch Hardware subarchitecture
......@@ -182,6 +187,8 @@ Offset Proto Name Meaning
024C/4 2.08+ payload_length Length of kernel payload
0250/8 2.09+ setup_data 64-bit physical pointer to linked list
of struct setup_data
0258/8 2.10+ pref_address Preferred loading address
0260/4 2.10+ init_size Linear memory required during initialization
(1) For backwards compatibility, if the setup_sects field contains 0, the
real value is 4.
......@@ -190,6 +197,8 @@ Offset Proto Name Meaning
field are unusable, which means the size of a bzImage kernel
cannot be determined.
(3) Ignored, but safe to set, for boot protocols 2.02-2.09.
If the "HdrS" (0x53726448) magic number is not found at offset 0x202,
the boot protocol version is "old". Loading an old kernel, the
following parameters should be assumed:
......@@ -343,18 +352,32 @@ Protocol: 2.00+
0xTV here, where T is an identifier for the boot loader and V is
a version number. Otherwise, enter 0xFF here.
For boot loader IDs above T = 0xD, write T = 0xE to this field and
write the extended ID minus 0x10 to the ext_loader_type field.
Similarly, the ext_loader_ver field can be used to provide more than
four bits for the bootloader version.
For example, for T = 0x15, V = 0x234, write:
type_of_loader <- 0xE4
ext_loader_type <- 0x05
ext_loader_ver <- 0x23
Assigned boot loader ids:
0 LILO (0x00 reserved for pre-2.00 bootloader)
1 Loadlin
2 bootsect-loader (0x20, all other values reserved)
3 SYSLINUX
4 EtherBoot
3 Syslinux
4 Etherboot/gPXE
5 ELILO
7 GRUB
8 U-BOOT
8 U-Boot
9 Xen
A Gujin
B Qemu
C Arcturus Networks uCbootloader
E Extended (see ext_loader_type)
F Special (0xFF = undefined)
Please contact <hpa@zytor.com> if you need a bootloader ID
value assigned.
......@@ -453,6 +476,35 @@ Protocol: 2.01+
Set this field to the offset (from the beginning of the real-mode
code) of the end of the setup stack/heap, minus 0x0200.
Field name: ext_loader_ver
Type: write (optional)
Offset/size: 0x226/1
Protocol: 2.02+
This field is used as an extension of the version number in the
type_of_loader field. The total version number is considered to be
(type_of_loader & 0x0f) + (ext_loader_ver << 4).
The use of this field is boot loader specific. If not written, it
is zero.
Kernels prior to 2.6.31 did not recognize this field, but it is safe
to write for protocol version 2.02 or higher.
Field name: ext_loader_type
Type: write (obligatory if (type_of_loader & 0xf0) == 0xe0)
Offset/size: 0x227/1
Protocol: 2.02+
This field is used as an extension of the type number in
type_of_loader field. If the type in type_of_loader is 0xE, then
the actual type is (ext_loader_type + 0x10).
This field is ignored if the type in type_of_loader is not 0xE.
Kernels prior to 2.6.31 did not recognize this field, but it is safe
to write for protocol version 2.02 or higher.
Field name: cmd_line_ptr
Type: write (obligatory)
Offset/size: 0x228/4
......@@ -482,11 +534,19 @@ Protocol: 2.03+
0x37FFFFFF, you can start your ramdisk at 0x37FE0000.)
Field name: kernel_alignment
Type: read (reloc)
Type: read/modify (reloc)
Offset/size: 0x230/4
Protocol: 2.05+
Protocol: 2.05+ (read), 2.10+ (modify)
Alignment unit required by the kernel (if relocatable_kernel is
true.) A relocatable kernel that is loaded at an alignment
incompatible with the value in this field will be realigned during
kernel initialization.
Alignment unit required by the kernel (if relocatable_kernel is true.)
Starting with protocol version 2.10, this reflects the kernel
alignment preferred for optimal performance; it is possible for the
loader to modify this field to permit a lesser alignment. See the
min_alignment and pref_address field below.
Field name: relocatable_kernel
Type: read (reloc)
......@@ -498,6 +558,22 @@ Protocol: 2.05+
After loading, the boot loader must set the code32_start field to
point to the loaded code, or to a boot loader hook.
Field name: min_alignment
Type: read (reloc)
Offset/size: 0x235/1
Protocol: 2.10+
This field, if nonzero, indicates as a power of two the minimum
alignment required, as opposed to preferred, by the kernel to boot.
If a boot loader makes use of this field, it should update the
kernel_alignment field with the alignment unit desired; typically:
kernel_alignment = 1 << min_alignment
There may be a considerable performance cost with an excessively
misaligned kernel. Therefore, a loader should typically try each
power-of-two alignment from kernel_alignment down to this alignment.
Field name: cmdline_size
Type: read
Offset/size: 0x238/4
......@@ -582,6 +658,36 @@ Protocol: 2.09+
sure to consider the case where the linked list already contains
entries.
Field name: pref_address
Type: read (reloc)
Offset/size: 0x258/8
Protocol: 2.10+
This field, if nonzero, represents a preferred load address for the
kernel. A relocating bootloader should attempt to load at this
address if possible.
A non-relocatable kernel will unconditionally move itself and to run
at this address.
Field name: init_size
Type: read
Offset/size: 0x25c/4
This field indicates the amount of linear contiguous memory starting
at the kernel runtime start address that the kernel needs before it
is capable of examining its memory map. This is not the same thing
as the total amount of memory the kernel needs to boot, but it can
be used by a relocating boot loader to help select a safe load
address for the kernel.
The kernel runtime start address is determined by the following algorithm:
if (relocatable_kernel)
runtime_start = align_up(load_address, kernel_alignment)
else
runtime_start = pref_address
**** THE IMAGE CHECKSUM
......
obj-$(CONFIG_KVM) += kvm/
# Xen paravirtualization support
obj-$(CONFIG_XEN) += xen/
# lguest paravirtualization support
obj-$(CONFIG_LGUEST_GUEST) += lguest/
obj-y += kernel/
obj-y += mm/
obj-y += crypto/
obj-y += vdso/
obj-$(CONFIG_IA32_EMULATION) += ia32/
......@@ -47,6 +47,11 @@ config X86
select HAVE_KERNEL_BZIP2
select HAVE_KERNEL_LZMA
config OUTPUT_FORMAT
string
default "elf32-i386" if X86_32
default "elf64-x86-64" if X86_64
config ARCH_DEFCONFIG
string
default "arch/x86/configs/i386_defconfig" if X86_32
......@@ -1460,9 +1465,7 @@ config KEXEC_JUMP
config PHYSICAL_START
hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
default "0x1000000" if X86_NUMAQ
default "0x200000" if X86_64
default "0x100000"
default "0x1000000"
---help---
This gives the physical address where the kernel is loaded.
......@@ -1481,15 +1484,15 @@ config PHYSICAL_START
to be specifically compiled to run from a specific memory area
(normally a reserved region) and this option comes handy.
So if you are using bzImage for capturing the crash dump, leave
the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
Otherwise if you plan to use vmlinux for capturing the crash dump
change this value to start of the reserved region (Typically 16MB
0x1000000). In other words, it can be set based on the "X" value as
specified in the "crashkernel=YM@XM" command line boot parameter
passed to the panic-ed kernel. Typically this parameter is set as
crashkernel=64M@16M. Please take a look at
Documentation/kdump/kdump.txt for more details about crash dumps.
So if you are using bzImage for capturing the crash dump,
leave the value here unchanged to 0x1000000 and set
CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
for capturing the crash dump change this value to start of
the reserved region. In other words, it can be set based on
the "X" value as specified in the "crashkernel=YM@XM"
command line boot parameter passed to the panic-ed
kernel. Please take a look at Documentation/kdump/kdump.txt
for more details about crash dumps.
Usage of bzImage for capturing the crash dump is recommended as
one does not have to build two kernels. Same kernel can be used
......@@ -1502,8 +1505,8 @@ config PHYSICAL_START
Don't change this unless you know what you are doing.
config RELOCATABLE
bool "Build a relocatable kernel (EXPERIMENTAL)"
depends on EXPERIMENTAL
bool "Build a relocatable kernel"
default y
---help---
This builds a kernel image that retains relocation information
so it can be loaded someplace besides the default 1MB.
......@@ -1518,12 +1521,16 @@ config RELOCATABLE
it has been loaded at and the compile time physical address
(CONFIG_PHYSICAL_START) is ignored.
# Relocation on x86-32 needs some additional build support
config X86_NEED_RELOCS
def_bool y
depends on X86_32 && RELOCATABLE
config PHYSICAL_ALIGN
hex
prompt "Alignment value to which kernel should be aligned" if X86_32
default "0x100000" if X86_32
default "0x200000" if X86_64
range 0x2000 0x400000
default "0x1000000"
range 0x2000 0x1000000
---help---
This value puts the alignment restrictions on physical address
where kernel is loaded and run from. Kernel is compiled for an
......
......@@ -7,8 +7,6 @@ else
KBUILD_DEFCONFIG := $(ARCH)_defconfig
endif
core-$(CONFIG_KVM) += arch/x86/kvm/
# BITS is used as extension for files which are available in a 32 bit
# and a 64 bit version to simplify shared Makefiles.
# e.g.: obj-y += foo_$(BITS).o
......@@ -118,21 +116,8 @@ head-y += arch/x86/kernel/init_task.o
libs-y += arch/x86/lib/
# Sub architecture files that needs linking first
core-y += $(fcore-y)
# Xen paravirtualization support
core-$(CONFIG_XEN) += arch/x86/xen/
# lguest paravirtualization support
core-$(CONFIG_LGUEST_GUEST) += arch/x86/lguest/
core-y += arch/x86/kernel/
core-y += arch/x86/mm/
core-y += arch/x86/crypto/
core-y += arch/x86/vdso/
core-$(CONFIG_IA32_EMULATION) += arch/x86/ia32/
# See arch/x86/Kbuild for content of core part of the kernel
core-y += arch/x86/
# drivers-y are linked after core-y
drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/
......
......@@ -3,6 +3,8 @@ bzImage
cpustr.h
mkcpustr
offsets.h
voffset.h
zoffset.h
setup
setup.bin
setup.elf
......@@ -86,19 +86,27 @@ $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE
SETUP_OBJS = $(addprefix $(obj)/,$(setup-y))
sed-offsets := -e 's/^00*/0/' \
-e 's/^\([0-9a-fA-F]*\) . \(input_data\|input_data_end\)$$/\#define \2 0x\1/p'
sed-voffset := -e 's/^\([0-9a-fA-F]*\) . \(_text\|_end\)$$/\#define VO_\2 0x\1/p'
quiet_cmd_offsets = OFFSETS $@
cmd_offsets = $(NM) $< | sed -n $(sed-offsets) > $@
quiet_cmd_voffset = VOFFSET $@
cmd_voffset = $(NM) $< | sed -n $(sed-voffset) > $@
$(obj)/offsets.h: $(obj)/compressed/vmlinux FORCE
$(call if_changed,offsets)
targets += voffset.h
$(obj)/voffset.h: vmlinux FORCE
$(call if_changed,voffset)
sed-zoffset := -e 's/^\([0-9a-fA-F]*\) . \(startup_32\|input_data\|_end\|z_.*\)$$/\#define ZO_\2 0x\1/p'
quiet_cmd_zoffset = ZOFFSET $@
cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@
targets += zoffset.h
$(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE
$(call if_changed,zoffset)
targets += offsets.h
AFLAGS_header.o += -I$(obj)
$(obj)/header.o: $(obj)/offsets.h
$(obj)/header.o: $(obj)/voffset.h $(obj)/zoffset.h
LDFLAGS_setup.elf := -T
$(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE
......
relocs
vmlinux.bin.all
vmlinux.relocs
vmlinux.lds
mkpiggy
piggy.S
......@@ -19,7 +19,9 @@ KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
LDFLAGS := -m elf_$(UTS_MACHINE)
LDFLAGS_vmlinux := -T
$(obj)/vmlinux: $(src)/vmlinux_$(BITS).lds $(obj)/head_$(BITS).o $(obj)/misc.o $(obj)/piggy.o FORCE
hostprogs-y := mkpiggy
$(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/head_$(BITS).o $(obj)/misc.o $(obj)/piggy.o FORCE
$(call if_changed,ld)
@:
......@@ -29,7 +31,7 @@ $(obj)/vmlinux.bin: vmlinux FORCE
targets += vmlinux.bin.all vmlinux.relocs relocs
hostprogs-$(CONFIG_X86_32) += relocs
hostprogs-$(CONFIG_X86_NEED_RELOCS) += relocs
quiet_cmd_relocs = RELOCS $@
cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $<
......@@ -37,46 +39,22 @@ $(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE
$(call if_changed,relocs)
vmlinux.bin.all-y := $(obj)/vmlinux.bin
vmlinux.bin.all-$(CONFIG_RELOCATABLE) += $(obj)/vmlinux.relocs
quiet_cmd_relocbin = BUILD $@
cmd_relocbin = cat $(filter-out FORCE,$^) > $@
$(obj)/vmlinux.bin.all: $(vmlinux.bin.all-y) FORCE
$(call if_changed,relocbin)
ifeq ($(CONFIG_X86_32),y)
vmlinux.bin.all-$(CONFIG_X86_NEED_RELOCS) += $(obj)/vmlinux.relocs
ifdef CONFIG_RELOCATABLE
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin.all FORCE
$(call if_changed,gzip)
$(obj)/vmlinux.bin.bz2: $(obj)/vmlinux.bin.all FORCE
$(call if_changed,bzip2)
$(obj)/vmlinux.bin.lzma: $(obj)/vmlinux.bin.all FORCE
$(call if_changed,lzma)
else
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
$(obj)/vmlinux.bin.gz: $(vmlinux.bin.all-y) FORCE
$(call if_changed,gzip)
$(obj)/vmlinux.bin.bz2: $(obj)/vmlinux.bin FORCE
$(obj)/vmlinux.bin.bz2: $(vmlinux.bin.all-y) FORCE
$(call if_changed,bzip2)
$(obj)/vmlinux.bin.lzma: $(obj)/vmlinux.bin FORCE
$(obj)/vmlinux.bin.lzma: $(vmlinux.bin.all-y) FORCE
$(call if_changed,lzma)
endif
LDFLAGS_piggy.o := -r --format binary --oformat elf32-i386 -T
else
suffix-$(CONFIG_KERNEL_GZIP) := gz
suffix-$(CONFIG_KERNEL_BZIP2) := bz2
suffix-$(CONFIG_KERNEL_LZMA) := lzma
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
$(call if_changed,gzip)
$(obj)/vmlinux.bin.bz2: $(obj)/vmlinux.bin FORCE
$(call if_changed,bzip2)
$(obj)/vmlinux.bin.lzma: $(obj)/vmlinux.bin FORCE
$(call if_changed,lzma)
LDFLAGS_piggy.o := -r --format binary --oformat elf64-x86-64 -T
endif
quiet_cmd_mkpiggy = MKPIGGY $@
cmd_mkpiggy = $(obj)/mkpiggy $< > $@ || ( rm -f $@ ; false )
suffix_$(CONFIG_KERNEL_GZIP) = gz
suffix_$(CONFIG_KERNEL_BZIP2) = bz2
suffix_$(CONFIG_KERNEL_LZMA) = lzma
$(obj)/piggy.o: $(obj)/vmlinux.scr $(obj)/vmlinux.bin.$(suffix_y) FORCE
$(call if_changed,ld)
targets += piggy.S
$(obj)/piggy.S: $(obj)/vmlinux.bin.$(suffix-y) $(obj)/mkpiggy FORCE
$(call if_changed,mkpiggy)
......@@ -12,16 +12,16 @@
* the page directory. [According to comments etc elsewhere on a compressed
* kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC]
*
* Page 0 is deliberately kept safe, since System Management Mode code in
* Page 0 is deliberately kept safe, since System Management Mode code in
* laptops may need to access the BIOS data stored there. This is also
* useful for future device drivers that either access the BIOS via VM86
* useful for future device drivers that either access the BIOS via VM86
* mode.
*/
/*
* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
*/
.text
.text
#include <linux/linkage.h>
#include <asm/segment.h>
......@@ -29,161 +29,151 @@
#include <asm/boot.h>
#include <asm/asm-offsets.h>
.section ".text.head","ax",@progbits
.section ".text.head","ax",@progbits
ENTRY(startup_32)
cld
/* test KEEP_SEGMENTS flag to see if the bootloader is asking
* us to not reload segments */
testb $(1<<6), BP_loadflags(%esi)
jnz 1f
/*
* Test KEEP_SEGMENTS flag to see if the bootloader is asking
* us to not reload segments
*/
testb $(1<<6), BP_loadflags(%esi)
jnz 1f
cli
movl $(__BOOT_DS),%eax
movl %eax,%ds
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
movl %eax,%ss
movl $__BOOT_DS, %eax
movl %eax, %ds
movl %eax, %es
movl %eax, %fs
movl %eax, %gs
movl %eax, %ss
1:
/* Calculate the delta between where we were compiled to run
/*
* Calculate the delta between where we were compiled to run
* at and where we were actually loaded at. This can only be done
* with a short local call on x86. Nothing else will tell us what
* address we are running at. The reserved chunk of the real-mode
* data at 0x1e4 (defined as a scratch field) are used as the stack
* for this calculation. Only 4 bytes are needed.
*/
leal (0x1e4+4)(%esi), %esp
call 1f
1: popl %ebp
subl $1b, %ebp
leal (BP_scratch+4)(%esi), %esp
call 1f
1: popl %ebp
subl $1b, %ebp
/* %ebp contains the address we are loaded at by the boot loader and %ebx
/*
* %ebp contains the address we are loaded at by the boot loader and %ebx
* contains the address where we should move the kernel image temporarily
* for safe in-place decompression.
*/
#ifdef CONFIG_RELOCATABLE
movl %ebp, %ebx
addl $(CONFIG_PHYSICAL_ALIGN - 1), %ebx
andl $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebx
movl %ebp, %ebx
movl BP_kernel_alignment(%esi), %eax
decl %eax
addl %eax, %ebx
notl %eax
andl %eax, %ebx
#else
movl $LOAD_PHYSICAL_ADDR, %ebx
movl $LOAD_PHYSICAL_ADDR, %ebx
#endif
/* Replace the compressed data size with the uncompressed size */
subl input_len(%ebp), %ebx
movl output_len(%ebp), %eax
addl %eax, %ebx
/* Add 8 bytes for every 32K input block */
shrl $12, %eax
addl %eax, %ebx
/* Add 32K + 18 bytes of extra slack */
addl $(32768 + 18), %ebx
/* Align on a 4K boundary */
addl $4095, %ebx
andl $~4095, %ebx
/* Copy the compressed kernel to the end of our buffer
/* Target address to relocate to for decompression */
addl $z_extract_offset, %ebx
/* Set up the stack */
leal boot_stack_end(%ebx), %esp
/* Zero EFLAGS */
pushl $0
popfl
/*
* Copy the compressed kernel to the end of our buffer
* where decompression in place becomes safe.
*/
pushl %esi
leal _end(%ebp), %esi
leal _end(%ebx), %edi
movl $(_end - startup_32), %ecx
pushl %esi
leal (_bss-4)(%ebp), %esi
leal (_bss-4)(%ebx), %edi
movl $(_bss - startup_32), %ecx
shrl $2, %ecx
std
rep
movsb
rep movsl
cld
popl %esi
/* Compute the kernel start address.
*/
#ifdef CONFIG_RELOCATABLE
addl $(CONFIG_PHYSICAL_ALIGN - 1), %ebp
andl $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebp
#else
movl $LOAD_PHYSICAL_ADDR, %ebp
#endif
popl %esi
/*
* Jump to the relocated address.
*/
leal relocated(%ebx), %eax
jmp *%eax
leal relocated(%ebx), %eax
jmp *%eax
ENDPROC(startup_32)
.section ".text"
.text
relocated:
/*
* Clear BSS
*/
xorl %eax,%eax
leal _edata(%ebx),%edi
leal _end(%ebx), %ecx
subl %edi,%ecx
cld
rep
stosb
/*
* Setup the stack for the decompressor
* Clear BSS (stack is currently empty)
*/
leal boot_stack_end(%ebx), %esp
xorl %eax, %eax
leal _bss(%ebx), %edi
leal _ebss(%ebx), %ecx
subl %edi, %ecx