Lines Matching +full:mode +full:- +full:loader
1 .. SPDX-License-Identifier: GPL-2.0
12 real-mode DOS as a mainstream operating system.
22 boot loader and the kernel. setup.S made relocatable,
28 Protocol 2.02 (Kernel 2.4.0-test3-pre3) New command line protocol.
31 safe for systems which use the EBDA from SMM or 32-bit
35 Protocol 2.03 (Kernel 2.4.18-pre1) Explicitly makes the highest possible
40 Protocol 2.05 (Kernel 2.6.20) Make protected mode kernel relocatable.
54 Protocol 2.09 (Kernel 2.6.26) Added a field of 64-bit physical
59 pref_address fields. Added extended boot loader IDs.
68 Protocol 2.13 (Kernel 3.14) Support 32- and 64-bit flags being set in
69 xloadflags to support booting a 64-bit kernel from 32-bit
86 features to the boot loader. Due to very limited space available in
89 communicate things to the boot loader is the kernel_info.
95 The traditional memory map for the kernel loader, used for Image or
99 0A0000 +------------------------+
101 09A000 +------------------------+
103 | Stack/heap | For use by the kernel real-mode code.
104 098000 +------------------------+
105 | Kernel setup | The kernel real-mode code.
106 090200 +------------------------+
108 090000 +------------------------+
109 | Protected-mode kernel | The bulk of the kernel image.
110 010000 +------------------------+
111 | Boot loader | <- Boot sector entry point 0000:7C00
112 001000 +------------------------+
114 000800 +------------------------+
116 000600 +------------------------+
118 000000 +------------------------+
120 When using bzImage, the protected-mode kernel was relocated to
121 0x100000 ("high memory"), and the kernel real-mode block (boot sector,
127 It is desirable to keep the "memory ceiling" -- the highest point in
128 low memory touched by the boot loader -- as low as possible, since
131 memory. The boot loader should use the "INT 12h" BIOS call to verify
135 low, there is usually nothing the boot loader can do but to report an
136 error to the user. The boot loader should therefore be designed to
139 0x90000 segment, the boot loader should make sure not to use memory
146 | Protected-mode kernel |
147 100000 +------------------------+
149 0A0000 +------------------------+
153 X+10000 +------------------------+
154 | Stack/heap | For use by the kernel real-mode code.
155 X+08000 +------------------------+
156 | Kernel setup | The kernel real-mode code.
158 X +------------------------+
159 | Boot loader | <- Boot sector entry point 0000:7C00
160 001000 +------------------------+
162 000800 +------------------------+
164 000600 +------------------------+
166 000000 +------------------------+
168 ... where the address X is as low as the design of the boot loader permits.
171 The Real-Mode Kernel Header
179 real-mode code (boot sector and setup code) and then examine the
180 following header at offset 0x01f1. The real-mode code can total up to
181 32K, although the boot loader may choose to load only the first two
191 01F4/4 2.04+(2) syssize The size of the 32-bit code in 16-byte paras
192 01F8/2 ALL ram_size DO NOT USE - for bootsect.S use only
193 01FA/2 ALL vid_mode Video mode control
199 0208/4 2.00+ realmode_swtch Boot loader hook (see below)
200 020C/2 2.00+ start_sys_seg The load-low segment (0x1000) (obsolete)
202 0210/1 2.00+ type_of_loader Boot loader identifier
205 0214/4 2.00+ code32_start Boot loader hook (see below)
206 0218/4 2.00+ ramdisk_image initrd load address (set by boot loader)
207 021C/4 2.00+ ramdisk_size initrd size (set by boot loader)
208 0220/4 2.00+ bootsect_kludge DO NOT USE - for bootsect.S use only
210 0226/1 2.02+(3) ext_loader_ver Extended boot loader version
211 0227/1 2.02+(3) ext_loader_type Extended boot loader ID
212 0228/4 2.02+ cmd_line_ptr 32-bit pointer to the kernel command line
220 0240/8 2.07+ hardware_subarch_data Subarchitecture-specific data
223 0250/8 2.09+ setup_data 64-bit physical pointer to linked list
239 (3) Ignored, but safe to set, for boot protocols 2.02-2.09.
247 Real-mode kernel must be located at 0x90000.
277 The size of the setup code in 512-byte sectors. If this field is
278 0, the real value is 4. The real-mode code consists of the boot
279 sector (always one 512-byte sector) plus the setup code.
299 The size of the protected-mode code in units of 16-byte paragraphs.
379 Boot loader hook (see ADVANCED BOOT LOADER HOOKS below.)
397 If set to a nonzero value, contains a pointer to a NUL-terminated
398 human-readable kernel version number string, less 0x200. This can
419 If your boot loader has an assigned id (see table below), enter
420 0xTV here, where T is an identifier for the boot loader and V is
423 For boot loader IDs above T = 0xD, write T = 0xE to this field and
430 type_of_loader <- 0xE4
431 ext_loader_type <- 0x05
432 ext_loader_ver <- 0x23
434 Assigned boot loader ids (hexadecimal):
438 (0x00 reserved for pre-2.00 bootloader)
440 2 bootsect-loader
446 8 U-Boot
451 D kexec-tools
456 <http://sebastian-plotz.blogspot.de>
474 - If 0, the protected-mode code is loaded at 0x10000.
475 - If 1, the protected-mode code is loaded at 0x100000.
479 - Used internally by the compressed kernel to communicate
482 - If 1, KASLR enabled.
483 - If 0, KASLR disabled.
487 - If 0, print early messages.
488 - If 1, suppress early messages.
498 - This flag is obsolete.
511 Protocol: 2.00-2.01
514 When using protocol 2.00 or 2.01, if the real mode kernel is not
517 the kernel command line) moved in addition to the real-mode kernel
523 if the real-mode code is loaded at 0x90000.
532 The address to jump to in protected mode. This defaults to the load
533 address of the kernel, and can be used by the boot loader to
538 1. as a boot loader hook (see Advanced Boot Loader Hooks below.)
551 The 32-bit linear address of the initial ramdisk or ramfs. Leave at
580 Set this field to the offset (from the beginning of the real-mode
594 The use of this field is boot loader specific. If not written, it
626 same 64K segment as the real-mode code itself.
628 Fill in this field even if your boot loader does not support a
631 zero, the kernel will assume that your boot loader does not support
662 loader to modify this field to permit a lesser alignment. See the
672 If this field is nonzero, the protected-mode part of the kernel can
674 After loading, the boot loader must set the code32_start field to
675 point to the loaded code, or to a boot loader hook.
686 If a boot loader makes use of this field, it should update the
692 misaligned kernel. Therefore, a loader should typically try each
693 power-of-two alignment from kernel_alignment down to this alignment.
706 - If 1, this kernel has the legacy 64-bit entry point at 0x200.
710 - If 1, kernel/boot_params/cmdline/ramdisk can be above 4G.
714 - If 1, the kernel supports the 32-bit EFI handoff entry point
719 - If 1, the kernel supports the 64-bit EFI handoff entry point
724 - If 1, the kernel supports kexec EFI boot with EFI runtime support.
763 Type: write (subarch-dependent)
779 If non-zero then this field contains the offset from the beginning
780 of the protected-mode code to the payload.
806 The 64-bit physical pointer to NULL terminated single linked list of
818 Where, the next is a 64-bit physical pointer to the next node of
830 and because it has a 32-bit length field. However, it is important that
880 A non-relocatable kernel will unconditionally move itself and to run
894 be used by a relocating boot loader to help select a safe load
908 a boot loader as::
934 in the uncompressed protected mode region.
951 a long time, for lack of alternatives and -- especially early on -- inertia.
953 available to a BIOS-based loader (setup_data is, though).
956 2-byte jump field, which doubles as a length field for the structure, combined
957 with the size of the "hole" in struct boot_params that a protected-mode loader
964 the kernel image, because it is .bss and has no image-provided content.
979 .long kernel_info_var_len_data - kernel_info
980 .long kernel_info_end - kernel_info
985 .long example_struct_end - example_struct
991 .long example_strings_end - example_strings
997 This way the kernel_info is self-contained blob.
1000 Each variable size data header/magic can be any 4-character string,
1044 From boot protocol version 2.08 onwards the CRC-32 is calculated over
1055 loader to communicate with the kernel. Some of its options are also
1056 relevant to the boot loader itself, see "special command line options"
1059 The kernel command line is a null-terminated string. The maximum
1072 - At offset 0x0020 (word), "cmd_line_magic", enter the magic
1075 - At offset 0x0022 (word), "cmd_line_offset", enter the offset
1077 real-mode kernel).
1079 - The kernel command line *must* be within the memory region
1084 Memory Layout of The Real-Mode Code
1087 The real-mode code requires a stack/heap to be set up, as well as
1089 in the real-mode accessible memory in bottom megabyte.
1098 - When loading a zImage kernel ((loadflags & 0x01) == 0).
1099 - When loading a 2.01 or earlier boot protocol kernel.
1102 For the 2.00 and 2.01 boot protocols, the real-mode code
1105 real-mode code must be loaded at 0x90000.
1110 located in the same 64K segment as the real-mode setup code; it is
1114 The kernel command line should not be located below the real-mode
1122 mode segment.
1127 0x0000-0x7fff Real mode kernel
1128 0x8000-0xdfff Stack and heap
1129 0xe000-0xffff Kernel command line
1135 0x0000-0x7fff Real mode kernel
1136 0x8000-0x97ff Stack and heap
1137 0x9800-0x9fff Kernel command line
1140 Such a boot loader should enter the following fields in the header::
1142 unsigned long base_ptr; /* base address for real-mode segment */
1160 heap_end_ptr = heap_end - 0x200;
1181 /* A very old kernel MUST have its real-mode code loaded at 0x90000 */
1183 /* Copy the real-mode kernel */
1191 memset(0x90000 + (setup_sects + 1) * 512, 0, (64 - (setup_sects + 1)) * 512);
1198 The 32-bit (non-real-mode) kernel starts at offset (setup_sects + 1) * 512
1211 0x10000-0x90000 range of memory. This means it is pretty much a
1212 requirement for these kernels to load the real-mode part at 0x90000.
1218 If the command line provided by the boot loader is entered by the
1222 loader authors who need additional command line options for the boot
1223 loader itself should get them registered in
1224 Documentation/admin-guide/kernel-parameters.rst to make sure they will not
1227 vga=<mode>
1228 <mode> here is either an integer (in C notation, either
1246 obviously bootloader-dependent, and some boot loaders
1250 user-specified command line:
1254 is obviously bootloader-dependent.
1259 If these options are added by the boot loader, it is highly
1260 recommended that they are located *first*, before the user-specified
1261 or configuration-specified command line. Otherwise, "init=/bin/sh"
1269 located at *segment* offset 0x20 from the start of the real mode
1270 kernel. This means that if you loaded your real-mode kernel code at
1273 At entry, ds = es = ss should point to the start of the real-mode
1277 the kernel, it is recommended that the boot loader sets fs = gs = ds =
1290 /* Set up the real-mode kernel stack */
1301 a demand-loaded module!
1304 Advanced Boot Loader Hooks
1307 If the boot loader runs in a particularly hostile environment (such as
1309 standard memory location requirements. Such a boot loader may use the
1318 A 16-bit real mode far subroutine invoked immediately before
1319 entering protected mode. The default routine disables NMI, so
1323 A 32-bit flat-mode routine *jumped* to immediately after the
1324 transition to protected mode, but before the kernel is
1330 that was in this field before your boot loader overwrote it
1334 32-bit Boot Protocol
1338 LinuxBIOS, etc, and kexec, the 16-bit real mode setup code in kernel
1339 based on legacy BIOS can not be used, so a 32-bit boot protocol needs
1342 In 32-bit boot protocol, the first step in loading a Linux kernel
1353 boot_params as that of 16-bit boot protocol, the boot loader should
1355 described in chapter Documentation/arch/x86/zero-page.rst.
1357 After setting up the struct boot_params, the boot loader can load the
1358 32/64-bit kernel in the same way as that of 16-bit boot protocol.
1360 In 32-bit boot protocol, the kernel is started by jumping to the
1361 32-bit kernel entry point, which is the start address of loaded
1362 32/64-bit kernel.
1364 At entry, the CPU must be in 32-bit protected mode with paging
1372 64-bit Boot Protocol
1376 and we need a 64-bit boot protocol.
1378 In 64-bit boot protocol, the first step in loading a Linux kernel
1389 boot_params as that of 16-bit boot protocol, the boot loader should
1391 in chapter Documentation/arch/x86/zero-page.rst.
1393 After setting up the struct boot_params, the boot loader can load
1394 64-bit kernel in the same way as that of 16-bit boot protocol, but
1397 In 64-bit boot protocol, the kernel is started by jumping to the
1398 64-bit kernel entry point, which is the start address of loaded
1399 64-bit kernel plus 0x200.
1401 At entry, the CPU must be in 64-bit mode with paging enabled.
1415 boot stub. The boot loader is required to load the kernel/initrd(s)
1417 which is hdr->handover_offset bytes from the beginning of
1420 The boot loader MUST respect the kernel's PE/COFF metadata when it comes
1430 'handle' is the EFI image handle passed to the boot loader by the EFI
1431 firmware, 'table' is the EFI system table - these are the first two
1433 UEFI specification. 'bp' is the boot loader-allocated boot params.
1435 The boot loader *must* fill out the following fields in bp::
1437 - hdr.cmd_line_ptr
1438 - hdr.ramdisk_image (if applicable)
1439 - hdr.ramdisk_size (if applicable)
1452 [0] https://github.com/u-boot/u-boot/commit/ec80b4735a593961fe701cc3a5d717d4739b0fd0