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x86, boot: make kernel_alignment adjustable; new bzImage fields

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Make the kernel_alignment field adjustable; this allows us to set it
to a large value (intended to be 16 MB to avoid ZONE_DMA contention,
memory holes and other weirdness) while a smart bootloader can still
force a loading at a lesser alignment if absolutely necessary.

Also export pref_address (preferred loading address, corresponding to
the link-time address) and init_size, the total amount of linear
memory the kernel will require during initialization.

[ Impact: allows better kernel placement, gives bootloader more info ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin
2009-05-11 15:56:08 -07:00
parent 99aa45595f
commit 37ba7ab5e3
6 changed files with 45 additions and 8 deletions
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7
arch/x86/boot/compressed/head_32.S
View File

@@ -69,8 +69,11 @@ ENTRY(startup_32)
#ifdef CONFIG_RELOCATABLE
movl %ebp, %ebx
addl $(CONFIG_PHYSICAL_ALIGN - 1), %ebx
andl $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebx
movl BP_kernel_alignment(%esi), %eax
decl %eax
addl %eax, %ebx
notl %eax
andl %eax, %ebx
#else
movl $LOAD_PHYSICAL_ADDR, %ebx
#endif

14
arch/x86/boot/compressed/head_64.S
View File

@@ -84,8 +84,11 @@ ENTRY(startup_32)
#ifdef CONFIG_RELOCATABLE
movl %ebp, %ebx
addl $(PMD_PAGE_SIZE -1), %ebx
andl $PMD_PAGE_MASK, %ebx
movl BP_kernel_alignment(%esi), %eax
decl %eax
addl %eax, %ebx
notl %eax
andl %eax, %ebx
#else
movl $LOAD_PHYSICAL_ADDR, %ebx
#endif
@@ -224,8 +227,11 @@ ENTRY(startup_64)
/* Start with the delta to where the kernel will run at. */
#ifdef CONFIG_RELOCATABLE
leaq startup_32(%rip) /* - $startup_32 */, %rbp
addq $(PMD_PAGE_SIZE - 1), %rbp
andq $PMD_PAGE_MASK, %rbp
movl BP_kernel_alignment(%rsi), %eax
decl %eax
addq %rax, %rbp
notq %rax
andq %rax, %rbp
#else
movq $LOAD_PHYSICAL_ADDR, %rbp
#endif

15
arch/x86/boot/header.S
View File

@@ -116,7 +116,7 @@ _start:
# Part 2 of the header, from the old setup.S
.ascii "HdrS" # header signature
.word 0x0209 # header version number (>= 0x0105)
.word 0x020a # header version number (>= 0x0105)
# or else old loadlin-1.5 will fail)
.globl realmode_swtch
realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
@@ -201,7 +201,7 @@ relocatable_kernel: .byte 1
#else
relocatable_kernel: .byte 0
#endif
pad2: .byte 0
min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment
pad3: .word 0
cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
@@ -220,6 +220,17 @@ setup_data: .quad 0 # 64-bit physical pointer to
# single linked list of
# struct setup_data
pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_extract_offset)
#define VO_INIT_SIZE (VO__end - VO__text)
#if ZO_INIT_SIZE > VO_INIT_SIZE
#define INIT_SIZE ZO_INIT_SIZE
#else
#define INIT_SIZE VO_INIT_SIZE
#endif
init_size: .long INIT_SIZE # kernel initialization size
# End of setup header #####################################################
.section ".inittext", "ax"