diff options
| -rw-r--r-- | Documentation/arch/x86/boot.rst | 194 |
1 files changed, 97 insertions, 97 deletions
diff --git a/Documentation/arch/x86/boot.rst b/Documentation/arch/x86/boot.rst index 77e6163288db08..ebb5c6fc422d5a 100644 --- a/Documentation/arch/x86/boot.rst +++ b/Documentation/arch/x86/boot.rst @@ -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>; - } - - 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 >= 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); - } + 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 >= 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); + } } 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); } |
