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+Summary of boot_params layout (kernel point of view)
+ ( collected by Hans Lermen and Martin Mares )
+The contents of boot_params are used to pass parameters from the
+16-bit realmode code of the kernel to the 32-bit part. References/settings
+to it mainly are in:
+ arch/i386/boot/setup.S
+ arch/i386/boot/video.S
+ arch/i386/kernel/head.S
+ arch/i386/kernel/setup.c
+Offset Type Description
+------ ---- -----------
+ 0 32 bytes struct screen_info, SCREEN_INFO
+ ATTENTION, overlaps the following !!!
+ 2 unsigned short EXT_MEM_K, extended memory size in Kb (from int 0x15)
+ 0x20 unsigned short CL_MAGIC, commandline magic number (=0xA33F)
+ 0x22 unsigned short CL_OFFSET, commandline offset
+ Address of commandline is calculated:
+ 0x90000 + contents of CL_OFFSET
+ (only taken, when CL_MAGIC = 0xA33F)
+ 0x40 20 bytes struct apm_bios_info, APM_BIOS_INFO
+ 0x60 16 bytes Intel SpeedStep (IST) BIOS support information
+ 0x80 16 bytes hd0-disk-parameter from intvector 0x41
+ 0x90 16 bytes hd1-disk-parameter from intvector 0x46
+ 0xa0 16 bytes System description table truncated to 16 bytes.
+ ( struct sys_desc_table_struct )
+ 0xb0 - 0x13f Free. Add more parameters here if you really need them.
+ 0x140- 0x1be EDID_INFO Video mode setup
+0x1c4 unsigned long EFI system table pointer
+0x1c8 unsigned long EFI memory descriptor size
+0x1cc unsigned long EFI memory descriptor version
+0x1d0 unsigned long EFI memory descriptor map pointer
+0x1d4 unsigned long EFI memory descriptor map size
+0x1e0 unsigned long ALT_MEM_K, alternative mem check, in Kb
+0x1e8 char number of entries in E820MAP (below)
+0x1e9 unsigned char number of entries in EDDBUF (below)
+0x1ea unsigned char number of entries in EDD_MBR_SIG_BUFFER (below)
+0x1f1 char size of setup.S, number of sectors
+0x1f2 unsigned short MOUNT_ROOT_RDONLY (if !=0)
+0x1f4 unsigned short size of compressed kernel-part in the
+ (b)zImage-file (in 16 byte units, rounded up)
+0x1f6 unsigned short swap_dev (unused AFAIK)
+0x1f8 unsigned short RAMDISK_FLAGS
+0x1fa unsigned short VGA-Mode (old one)
+0x1fc unsigned short ORIG_ROOT_DEV (high=Major, low=minor)
+0x1ff char AUX_DEVICE_INFO
+0x200 short jump to start of setup code aka "reserved" field.
+0x202 4 bytes Signature for SETUP-header, ="HdrS"
+0x206 unsigned short Version number of header format
+ Current version is 0x0201...
+0x208 8 bytes (used by setup.S for communication with boot loaders,
+ look there)
+0x210 char LOADER_TYPE, = 0, old one
+ else it is set by the loader:
+ 0xTV: T=0 for LILO
+ 1 for Loadlin
+ 2 for bootsect-loader
+ 3 for SYSLINUX
+ V = version
+0x211 char loadflags:
+ bit0 = 1: kernel is loaded high (bzImage)
+ bit7 = 1: Heap and pointer (see below) set by boot
+ loader.
+0x212 unsigned short (setup.S)
+0x214 unsigned long KERNEL_START, where the loader started the kernel
+0x218 unsigned long INITRD_START, address of loaded ramdisk image
+0x21c unsigned long INITRD_SIZE, size in bytes of ramdisk image
+0x220 4 bytes (setup.S)
+0x224 unsigned short setup.S heap end pointer
+0x226 unsigned short zero_pad
+0x228 unsigned long cmd_line_ptr
+0x22c unsigned long ramdisk_max
+0x230 16 bytes trampoline
+0x290 - 0x2cf EDD_MBR_SIG_BUFFER (edd.S)
+0x2d0 - 0x600 E820MAP
+0x600 - 0x7ff EDDBUF (edd.S) for disk signature read sector
+0x600 - 0x7eb EDDBUF (edd.S) for edd data