arch/x86/boot.rst

22 		boot loader and the kernel.  setup.S made relocatable,
59 		pref_address fields.  Added extended boot loader IDs.
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
111 		|  Boot loader		 |	<- Boot sector entry point 0000:7C00
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
159 		|  Boot loader		 |	<- Boot sector entry point 0000:7C00
168   ... where the address X is as low as the design of the boot loader permits.
181 32K, although the boot loader may choose to load only the first two
199 0208/4		2.00+		realmode_swtch		Boot loader hook (see below)
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)
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
379   Boot loader hook (see ADVANCED BOOT LOADER HOOKS below.)
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
434   Assigned boot loader ids (hexadecimal):
440 	2  bootsect-loader
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.)
594   The use of this field is boot loader specific.  If not written, it
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
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
893   be used by a relocating boot loader to help select a safe load
943 available to a BIOS-based loader (setup_data is, though).
947 with the size of the "hole" in struct boot_params that a protected-mode loader
1045 loader to communicate with the kernel.  Some of its options are also
1046 relevant to the boot loader itself, see "special command line options"
1130 Such a boot loader should enter the following fields in the header::
1211 If the command line provided by the boot loader is entered by the
1215 loader authors who need additional command line options for the boot
1216 loader itself should get them registered in
1252 If these options are added by the boot loader, it is highly
1270 the kernel, it is recommended that the boot loader sets fs = gs = ds =
1296 Advanced Boot Loader Hooks
1299 If the boot loader runs in a particularly hostile environment (such as
1301 standard memory location requirements.  Such a boot loader may use the
1322 	that was in this field before your boot loader overwrote it
1345 boot_params as that of 16-bit boot protocol, the boot loader should
1349 After setting up the struct boot_params, the boot loader can load the
1381 boot_params as that of 16-bit boot protocol, the boot loader should
1385 After setting up the struct boot_params, the boot loader can load
1407 boot stub. The boot loader is required to load the kernel/initrd(s)
1412 The boot loader MUST respect the kernel's PE/COFF metadata when it comes
1422 'handle' is the EFI image handle passed to the boot loader by the EFI
1425 UEFI specification. 'bp' is the boot loader-allocated boot params.
1427 The boot loader *must* fill out the following fields in bp::