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x86/boot/Documentation: Fix whitespace noise in boot.rst

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There's a lot of unnecessary whitespace damage in this
file: space before tabs, etc., that has no formatting
or readability effect or advantages.

Fix them.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://patch.msgid.link/176535283007.498.16442167388418039352.tip-bot2@tip-bot2
This commit is contained in:
Ingo Molnar
2025-12-10 08:36:18 +01:00
parent c8161e5304
commit ac87efcf9e
1 changed files with 94 additions and 94 deletions
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188
Documentation/arch/x86/boot.rst
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@@ -95,26 +95,26 @@ Memory Layout
The traditional memory map for the kernel loader, used for Image or
zImage kernels, typically looks like::
| |
| |
0A0000 +------------------------+
| Reserved for BIOS | Do not use. Reserved for BIOS EBDA.
| Reserved for BIOS | Do not use. Reserved for BIOS EBDA.
09A000 +------------------------+
| Command line |
| Stack/heap | For use by the kernel real-mode code.
| Command line |
| Stack/heap | For use by the kernel real-mode code.
098000 +------------------------+
| Kernel setup | The kernel real-mode code.
| Kernel setup | The kernel real-mode code.
090200 +------------------------+
| Kernel boot sector | The kernel legacy boot sector.
| Kernel boot sector | The kernel legacy boot sector.
090000 +------------------------+
| Protected-mode kernel | The bulk of the kernel image.
| Protected-mode kernel | The bulk of the kernel image.
010000 +------------------------+
| Boot loader | <- Boot sector entry point 0000:7C00
| Boot loader | <- Boot sector entry point 0000:7C00
001000 +------------------------+
| Reserved for MBR/BIOS |
| Reserved for MBR/BIOS |
000800 +------------------------+
| Typically used by MBR |
| Typically used by MBR |
000600 +------------------------+
| BIOS use only |
| BIOS use only |
000000 +------------------------+
When using bzImage, the protected-mode kernel was relocated to
@@ -142,27 +142,27 @@ above the 0x9A000 point; too many BIOSes will break above that point.
For a modern bzImage kernel with boot protocol version >= 2.02, a
memory layout like the following is suggested::
~ ~
| Protected-mode kernel |
~ ~
| Protected-mode kernel |
100000 +------------------------+
| I/O memory hole |
| I/O memory hole |
0A0000 +------------------------+
| Reserved for BIOS | Leave as much as possible unused
~ ~
| Command line | (Can also be below the X+10000 mark)
| Reserved for BIOS | Leave as much as possible unused
~ ~
| Command line | (Can also be below the X+10000 mark)
X+10000 +------------------------+
| Stack/heap | For use by the kernel real-mode code.
| Stack/heap | For use by the kernel real-mode code.
X+08000 +------------------------+
| Kernel setup | The kernel real-mode code.
| Kernel boot sector | The kernel legacy boot sector.
| Kernel setup | The kernel real-mode code.
| Kernel boot sector | The kernel legacy boot sector.
X +------------------------+
| Boot loader | <- Boot sector entry point 0000:7C00
| Boot loader | <- Boot sector entry point 0000:7C00
001000 +------------------------+
| Reserved for MBR/BIOS |
| Reserved for MBR/BIOS |
000800 +------------------------+
| Typically used by MBR |
| Typically used by MBR |
000600 +------------------------+
| BIOS use only |
| BIOS use only |
000000 +------------------------+
... where the address X is as low as the design of the boot loader permits.
@@ -809,12 +809,12 @@ Protocol: 2.09+
as follow::
struct setup_data {
__u64 next;
__u32 type;
__u32 len;
__u8 data[];
__u64 next;
__u32 type;
__u32 len;
__u8 data[];
}
Where, the next is a 64-bit physical pointer to the next node of
linked list, the next field of the last node is 0; the type is used
to identify the contents of data; the len is the length of data
@@ -835,10 +835,10 @@ Protocol: 2.09+
protocol 2.15::
struct setup_indirect {
__u32 type;
__u32 reserved; /* Reserved, must be set to zero. */
__u64 len;
__u64 addr;
__u32 type;
__u32 reserved; /* Reserved, must be set to zero. */
__u64 len;
__u64 addr;
};
The type member is a SETUP_INDIRECT | SETUP_* type. However, it cannot be
@@ -850,15 +850,15 @@ Protocol: 2.09+
In this case setup_data and setup_indirect will look like this::
struct setup_data {
.next = 0, /* or <addr_of_next_setup_data_struct> */
.type = SETUP_INDIRECT,
.len = sizeof(setup_indirect),
.data[sizeof(setup_indirect)] = (struct setup_indirect) {
.type = SETUP_INDIRECT | SETUP_E820_EXT,
.reserved = 0,
.len = <len_of_SETUP_E820_EXT_data>,
.addr = <addr_of_SETUP_E820_EXT_data>,
},
.next = 0, /* or <addr_of_next_setup_data_struct> */
.type = SETUP_INDIRECT,
.len = sizeof(setup_indirect),
.data[sizeof(setup_indirect)] = (struct setup_indirect) {
.type = SETUP_INDIRECT | SETUP_E820_EXT,
.reserved = 0,
.len = <len_of_SETUP_E820_EXT_data>,
.addr = <addr_of_SETUP_E820_EXT_data>,
},
}
.. note::
@@ -897,11 +897,11 @@ Offset/size: 0x260/4
The kernel runtime start address is determined by the following algorithm::
if (relocatable_kernel) {
if (load_address < pref_address)
load_address = pref_address;
runtime_start = align_up(load_address, kernel_alignment);
if (load_address < pref_address)
load_address = pref_address;
runtime_start = align_up(load_address, kernel_alignment);
} else {
runtime_start = pref_address;
runtime_start = pref_address;
}
Hence the necessary memory window location and size can be estimated by
@@ -975,22 +975,22 @@ after kernel_info_var_len_data label. Each chunk of variable size data has to
be prefixed with header/magic and its size, e.g.::
kernel_info:
.ascii "LToP" /* Header, Linux top (structure). */
.long kernel_info_var_len_data - kernel_info
.long kernel_info_end - kernel_info
.long 0x01234567 /* Some fixed size data for the bootloaders. */
.ascii "LToP" /* Header, Linux top (structure). */
.long kernel_info_var_len_data - kernel_info
.long kernel_info_end - kernel_info
.long 0x01234567 /* Some fixed size data for the bootloaders. */
kernel_info_var_len_data:
example_struct: /* Some variable size data for the bootloaders. */
.ascii "0123" /* Header/Magic. */
.long example_struct_end - example_struct
.ascii "Struct"
.long 0x89012345
.ascii "0123" /* Header/Magic. */
.long example_struct_end - example_struct
.ascii "Struct"
.long 0x89012345
example_struct_end:
example_strings: /* Some variable size data for the bootloaders. */
.ascii "ABCD" /* Header/Magic. */
.long example_strings_end - example_strings
.asciz "String_0"
.asciz "String_1"
.ascii "ABCD" /* Header/Magic. */
.long example_strings_end - example_strings
.asciz "String_0"
.asciz "String_1"
example_strings_end:
kernel_info_end:
@@ -1132,53 +1132,53 @@ Such a boot loader should enter the following fields in the header::
unsigned long base_ptr; /* base address for real-mode segment */
if (setup_sects == 0)
setup_sects = 4;
setup_sects = 4;
if (protocol >= 0x0200) {
type_of_loader = <type code>;
if (loading_initrd) {
ramdisk_image = <initrd_address>;
ramdisk_size = <initrd_size>;
}
type_of_loader = <type code>;
if (loading_initrd) {
ramdisk_image = <initrd_address>;
ramdisk_size = <initrd_size>;
}
if (protocol >= 0x0202 && loadflags & 0x01)
heap_end = 0xe000;
else
heap_end = 0x9800;
if (protocol >= 0x0202 && loadflags & 0x01)
heap_end = 0xe000;
else
heap_end = 0x9800;
if (protocol >= 0x0201) {
heap_end_ptr = heap_end - 0x200;
loadflags |= 0x80; /* CAN_USE_HEAP */
}
if (protocol >= 0x0201) {
heap_end_ptr = heap_end - 0x200;
loadflags |= 0x80; /* CAN_USE_HEAP */
}
if (protocol >= 0x0202) {
cmd_line_ptr = base_ptr + heap_end;
strcpy(cmd_line_ptr, cmdline);
} else {
cmd_line_magic = 0xA33F;
cmd_line_offset = heap_end;
setup_move_size = heap_end + strlen(cmdline) + 1;
strcpy(base_ptr + cmd_line_offset, cmdline);
}
if (protocol >= 0x0202) {
cmd_line_ptr = base_ptr + heap_end;
strcpy(cmd_line_ptr, cmdline);
} else {
cmd_line_magic = 0xA33F;
cmd_line_offset = heap_end;
setup_move_size = heap_end + strlen(cmdline) + 1;
strcpy(base_ptr + cmd_line_offset, cmdline);
}
} else {
/* Very old kernel */
/* Very old kernel */
heap_end = 0x9800;
heap_end = 0x9800;
cmd_line_magic = 0xA33F;
cmd_line_offset = heap_end;
cmd_line_magic = 0xA33F;
cmd_line_offset = heap_end;
/* A very old kernel MUST have its real-mode code loaded at 0x90000 */
if (base_ptr != 0x90000) {
/* Copy the real-mode kernel */
memcpy(0x90000, base_ptr, (setup_sects + 1) * 512);
base_ptr = 0x90000; /* Relocated */
}
/* A very old kernel MUST have its real-mode code loaded at 0x90000 */
if (base_ptr != 0x90000) {
/* Copy the real-mode kernel */
memcpy(0x90000, base_ptr, (setup_sects + 1) * 512);
base_ptr = 0x90000; /* Relocated */
}
strcpy(0x90000 + cmd_line_offset, cmdline);
strcpy(0x90000 + cmd_line_offset, cmdline);
/* It is recommended to clear memory up to the 32K mark */
memset(0x90000 + (setup_sects + 1) * 512, 0, (64 - (setup_sects + 1)) * 512);
/* It is recommended to clear memory up to the 32K mark */
memset(0x90000 + (setup_sects + 1) * 512, 0, (64 - (setup_sects + 1)) * 512);
}