f9ba70535d
The specifications that talk about E820 map doesn't have an upper limit on the number of e820 entries. But, today's kernel has a hard limit of 32. With increase in memory size, we are seeing the number of E820 entries reaching close to 32. Patch below bumps the number upto 128. The patch changes the location of EDDBUF in zero-page (as it comes after E820). As, EDDBUF is not used by boot loaders, this patch should not have any effect on bootloader-setup code interface. Patch covers both i386 and x86-64. Tested on: * grub booting bzImage * lilo booting bzImage with EDID info enabled * pxeboot of bzImage Side-effect: bss increases by ~ 2K and init.data increases by ~7.5K on all systems, due to increase in size of static arrays. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
84 lines
3.3 KiB
Text
84 lines
3.3 KiB
Text
Summary of boot_params layout (kernel point of view)
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( collected by Hans Lermen and Martin Mares )
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The contents of boot_params are used to pass parameters from the
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16-bit realmode code of the kernel to the 32-bit part. References/settings
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to it mainly are in:
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arch/i386/boot/setup.S
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arch/i386/boot/video.S
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arch/i386/kernel/head.S
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arch/i386/kernel/setup.c
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Offset Type Description
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------ ---- -----------
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0 32 bytes struct screen_info, SCREEN_INFO
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ATTENTION, overlaps the following !!!
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2 unsigned short EXT_MEM_K, extended memory size in Kb (from int 0x15)
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0x20 unsigned short CL_MAGIC, commandline magic number (=0xA33F)
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0x22 unsigned short CL_OFFSET, commandline offset
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Address of commandline is calculated:
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0x90000 + contents of CL_OFFSET
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(only taken, when CL_MAGIC = 0xA33F)
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0x40 20 bytes struct apm_bios_info, APM_BIOS_INFO
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0x60 16 bytes Intel SpeedStep (IST) BIOS support information
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0x80 16 bytes hd0-disk-parameter from intvector 0x41
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0x90 16 bytes hd1-disk-parameter from intvector 0x46
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0xa0 16 bytes System description table truncated to 16 bytes.
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( struct sys_desc_table_struct )
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0xb0 - 0x13f Free. Add more parameters here if you really need them.
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0x140- 0x1be EDID_INFO Video mode setup
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0x1c4 unsigned long EFI system table pointer
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0x1c8 unsigned long EFI memory descriptor size
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0x1cc unsigned long EFI memory descriptor version
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0x1d0 unsigned long EFI memory descriptor map pointer
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0x1d4 unsigned long EFI memory descriptor map size
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0x1e0 unsigned long ALT_MEM_K, alternative mem check, in Kb
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0x1e8 char number of entries in E820MAP (below)
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0x1e9 unsigned char number of entries in EDDBUF (below)
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0x1ea unsigned char number of entries in EDD_MBR_SIG_BUFFER (below)
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0x1f1 char size of setup.S, number of sectors
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0x1f2 unsigned short MOUNT_ROOT_RDONLY (if !=0)
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0x1f4 unsigned short size of compressed kernel-part in the
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(b)zImage-file (in 16 byte units, rounded up)
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0x1f6 unsigned short swap_dev (unused AFAIK)
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0x1f8 unsigned short RAMDISK_FLAGS
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0x1fa unsigned short VGA-Mode (old one)
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0x1fc unsigned short ORIG_ROOT_DEV (high=Major, low=minor)
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0x1ff char AUX_DEVICE_INFO
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0x200 short jump to start of setup code aka "reserved" field.
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0x202 4 bytes Signature for SETUP-header, ="HdrS"
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0x206 unsigned short Version number of header format
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Current version is 0x0201...
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0x208 8 bytes (used by setup.S for communication with boot loaders,
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look there)
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0x210 char LOADER_TYPE, = 0, old one
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else it is set by the loader:
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0xTV: T=0 for LILO
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1 for Loadlin
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2 for bootsect-loader
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3 for SYSLINUX
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4 for ETHERBOOT
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V = version
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0x211 char loadflags:
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bit0 = 1: kernel is loaded high (bzImage)
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bit7 = 1: Heap and pointer (see below) set by boot
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loader.
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0x212 unsigned short (setup.S)
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0x214 unsigned long KERNEL_START, where the loader started the kernel
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0x218 unsigned long INITRD_START, address of loaded ramdisk image
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0x21c unsigned long INITRD_SIZE, size in bytes of ramdisk image
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0x220 4 bytes (setup.S)
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0x224 unsigned short setup.S heap end pointer
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0x226 unsigned short zero_pad
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0x228 unsigned long cmd_line_ptr
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0x22c unsigned long ramdisk_max
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0x230 16 bytes trampoline
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0x290 - 0x2cf EDD_MBR_SIG_BUFFER (edd.S)
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0x2d0 - 0xd00 E820MAP
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0xd00 - 0xeff EDDBUF (edd.S) for disk signature read sector
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0xd00 - 0xeeb EDDBUF (edd.S) for edd data
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