- Please contact <hpa@zytor.com> if you need a bootloader ID
- value assigned.
-
- loadflags, heap_end_ptr:
- If the protocol version is 2.01 or higher, enter the
- offset limit of the setup heap into heap_end_ptr and set the
- 0x80 bit (CAN_USE_HEAP) of loadflags. heap_end_ptr appears to
- be relative to the start of setup (offset 0x0200).
-
- setup_move_size:
- When using protocol 2.00 or 2.01, if the real mode
- kernel is not loaded at 0x90000, it gets moved there later in
- the loading sequence. Fill in this field if you want
- additional data (such as the kernel command line) moved in
- addition to the real-mode kernel itself.
-
- The unit is bytes starting with the beginning of the boot
- sector.
-
- ramdisk_image, ramdisk_size:
- If your boot loader has loaded an initial ramdisk (initrd),
- set ramdisk_image to the 32-bit pointer to the ramdisk data
- and the ramdisk_size to the size of the ramdisk data.
-
- The initrd should typically be located as high in memory as
- possible, as it may otherwise get overwritten by the early
- kernel initialization sequence. However, it must never be
- located above the address specified in the initrd_addr_max
- field. The initrd should be at least 4K page aligned.
-
- cmd_line_ptr:
- If the protocol version is 2.02 or higher, this is a 32-bit
- pointer to the kernel command line. The kernel command line
- can be located anywhere between the end of setup and 0xA0000.
- Fill in this field even if your boot loader does not support a
- command line, in which case you can point this to an empty
- string (or better yet, to the string "auto".) If this field
- is left at zero, the kernel will assume that your boot loader
- does not support the 2.02+ protocol.
-
- ramdisk_max:
- The maximum address that may be occupied by the initrd
- contents. For boot protocols 2.02 or earlier, this field is
- not present, and the maximum address is 0x37FFFFFF. (This
- address is defined as the address of the highest safe byte, so
- if your ramdisk is exactly 131072 bytes long and this field is
- 0x37FFFFFF, you can start your ramdisk at 0x37FE0000.)
-
- cmdline_size:
- The maximum size of the command line without the terminating
- zero. This means that the command line can contain at most
- cmdline_size characters. With protocol version 2.05 and
- earlier, the maximum size was 255.
+ Please contact <hpa@zytor.com> if you need a bootloader ID
+ value assigned.
+
+Field name: loadflags
+Type: modify (obligatory)
+Offset/size: 0x211/1
+Protocol: 2.00+
+
+ This field is a bitmask.
+
+ Bit 0 (read): LOADED_HIGH
+ - If 0, the protected-mode code is loaded at 0x10000.
+ - If 1, the protected-mode code is loaded at 0x100000.
+
+ Bit 7 (write): CAN_USE_HEAP
+ Set this bit to 1 to indicate that the value entered in the
+ heap_end_ptr is valid. If this field is clear, some setup code
+ functionality will be disabled.
+
+Field name: setup_move_size
+Type: modify (obligatory)
+Offset/size: 0x212/2
+Protocol: 2.00-2.01
+
+ When using protocol 2.00 or 2.01, if the real mode kernel is not
+ loaded at 0x90000, it gets moved there later in the loading
+ sequence. Fill in this field if you want additional data (such as
+ the kernel command line) moved in addition to the real-mode kernel
+ itself.
+
+ The unit is bytes starting with the beginning of the boot sector.
+
+ This field is can be ignored when the protocol is 2.02 or higher, or
+ if the real-mode code is loaded at 0x90000.
+
+Field name: code32_start
+Type: modify (optional, reloc)
+Offset/size: 0x214/4
+Protocol: 2.00+
+
+ The address to jump to in protected mode. This defaults to the load
+ address of the kernel, and can be used by the boot loader to
+ determine the proper load address.
+
+ This field can be modified for two purposes:
+
+ 1. as a boot loader hook (see separate chapter.)
+
+ 2. if a bootloader which does not install a hook loads a
+ relocatable kernel at a nonstandard address it will have to modify
+ this field to point to the load address.
+
+Field name: ramdisk_image
+Type: write (obligatory)
+Offset/size: 0x218/4
+Protocol: 2.00+
+
+ The 32-bit linear address of the initial ramdisk or ramfs. Leave at
+ zero if there is no initial ramdisk/ramfs.
+
+Field name: ramdisk_size
+Type: write (obligatory)
+Offset/size: 0x21c/4
+Protocol: 2.00+
+
+ Size of the initial ramdisk or ramfs. Leave at zero if there is no
+ initial ramdisk/ramfs.
+
+Field name: bootsect_kludge
+Type: kernel internal
+Offset/size: 0x220/4
+Protocol: 2.00+
+
+ This field is obsolete.
+
+Field name: heap_end_ptr
+Type: write (obligatory)
+Offset/size: 0x224/2
+Protocol: 2.01+
+
+ Set this field to the offset (from the beginning of the real-mode
+ code) of the end of the setup stack/heap, minus 0x0200.
+
+Field name: cmd_line_ptr
+Type: write (obligatory)
+Offset/size: 0x228/4
+Protocol: 2.02+
+
+ Set this field to the linear address of the kernel command line.
+ The kernel command line can be located anywhere between the end of
+ the setup heap and 0xA0000; it does not have to be located in the
+ same 64K segment as the real-mode code itself.
+
+ Fill in this field even if your boot loader does not support a
+ command line, in which case you can point this to an empty string
+ (or better yet, to the string "auto".) If this field is left at
+ zero, the kernel will assume that your boot loader does not support
+ the 2.02+ protocol.
+
+Field name: initrd_addr_max
+Type: read
+Offset/size: 0x22c/4
+Protocol: 2.03+
+
+ The maximum address that may be occupied by the initial
+ ramdisk/ramfs contents. For boot protocols 2.02 or earlier, this
+ field is not present, and the maximum address is 0x37FFFFFF. (This
+ address is defined as the address of the highest safe byte, so if
+ your ramdisk is exactly 131072 bytes long and this field is
+ 0x37FFFFFF, you can start your ramdisk at 0x37FE0000.)
+
+Field name: kernel_alignment
+Type: read (reloc)
+Offset/size: 0x230/4
+Protocol: 2.05+
+
+ Alignment unit required by the kernel (if relocatable_kernel is true.)
+
+Field name: relocatable_kernel
+Type: read (reloc)
+Offset/size: 0x234/1
+Protocol: 2.05+
+
+ If this field is nonzero, the protected-mode part of the kernel can
+ be loaded at any address that satisfies the kernel_alignment field.
+ After loading, the boot loader must set the code32_start field to
+ point to the loaded code, or to a boot loader hook.
+
+Field name: cmdline_size
+Type: read
+Offset/size: 0x238/4
+Protocol: 2.06+
+
+ The maximum size of the command line without the terminating
+ zero. This means that the command line can contain at most
+ cmdline_size characters. With protocol version 2.05 and earlier, the
+ maximum size was 255.
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