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@@ -1,3336 +1 @@
-
-
-
-Linux 2.4.x Initialization for IA-32 HOWTO
-
-
-
-----
-
-!!!Linux 2.4.x Initialization for IA-32 HOWTO
-
-!!Randy Dunlap, rddunlap@ieee.orgv1., 2001-05-17
-
-
-----
-''This document contains a description of the Linux 2.4 kernel
-initialization sequence on IA-32 processors.''
-----
-
-
-
-
-!!1. Introduction
-
-
-*1.1 Overview
-
-*1.2 This document
-
-*1.3 Contributions
-
-*1.4 Trademarks
-
-*1.5 License
-
-
-
-
-
-!!2. Linux init ("ASCII art")
-
-
-
-
-!!3. Linux early setup
-
-
-*3.1 IA-32 Kernel Setup
-
-*3.2 Video Setup
-
-
-
-
-
-!!4. Linux architecture-specific initialization
-
-
-*4.1 startup_32:
-
-*4.2 Set segment registers to known values
-
-*4.3 SMP BSP (Bootstrap Processor) check
-
-*4.4 Initialize page tables
-
-*4.5 Enable paging
-
-*4.6 Clear BSS
-
-*4.7 32-bit setup
-
-*4.8 Copy boot parameters and command line out of the way
-
-*4.9 checkCPUtype
-
-*4.10 Count this processor
-
-*4.11 Load descriptor table pointer registers
-
-*4.12 Start other processors
-
-
-
-
-
-!!5. Linux architecture-independent initialization
-
-
-*5.1 start_kernel:
-
-*5.2 setup_arch
-
-*5.3 init thread
-
-*5.4 do_basic_setup {part of the init thread}
-
-
-
-
-
-!!6. Glossary
-
-
-
-
-!!7. References
-----
-
-!!1. Introduction
-
-
-
-
-
-Portions of this text come from comments in the kernel source
-files (obviously). I have added annotations in many places.
-I hope that this will be useful to kernel developers -- either
-new ones or experienced ones who need more of this type of
-information. However, if there's not enough detail here for
-you, "Use the Source."
-
-
-
-
-!!1.1 Overview
-
-
-
-
-
-
-This description is organized as a brief overview which
-lists the sections that are described later in more detail.
-
-
-The description is in three main sections. The first section covers
-early kernel initialization on IA-32 (but only after your boot loader of
-choice and other intermediate loaders have run; i.e., this description
-does not cover loading the kernel).
-This section is based on the code in "linux/arch/i386/boot/setup.S"
-and "linux/arch/i386/boot/video.S".
-
-
-The second major section covers Linux initialization that is
-x86- (or i386- or IA-32-) specific. This section is based on the source
-files "linux/arch/i386/kernel/head.S" and "linux/arch/i386/kernel/setup.c".
-
-
-The third major section covers Linux initialization that is
-architecture-independent. This section is based on the flow in the
-source file "linux/init/main.c".
-
-
-See the References section for other valuable documents
-about booting, loading, and initialization.
-
-
-
-
-!!1.2 This document
-
-
-
-
-
-
-This document describes Linux 2.4.x initialization on IA-32
-(or i386 or x86) processors -- after one or more kernel boot loaders
-(if any) have done their job.
-
-
-You can format it using the commands (for example):
-
-
-
-
-
-% sgml2txt ia32_init_240.sgml
-
-
-or
-
-
-% sgml2html ia32_init_240.sgml
-
-
-
-
-This will produce plain ASCII or HTML files respectively.
-You can also produce LaTeX, GNU, and RTF info by using the proper
-sgmltool (man sgmltools).
-
-
-
-
-!!1.3 Contributions
-
-
-
-
-
-
-Additions and corrections are welcome. Please send them
-to me (rddunlap@ieee.org). Contributions of section
-descriptions that are used will be credited to their author(s).
-
-
-
-
-!!1.4 Trademarks
-
-
-
-
-
-
-All trademarks are the property of their respective owners.
-
-
-
-
-!!1.5 License
-
-
-
-
-
-
-Copyright (C) 2001 Randy Dunlap.
-
-
-This document may be distributed only subject to the terms
-and conditions set forth in the LDP (Linux Documentation Project)
-License at "http://www.linuxdoc.org/COPYRIGHT.html".
-
-
-
-----
-
-!!2. Linux init ("ASCII art")
-
-
-
-
-
-Pictorially (loosely speaking :), Linux initialization looks like
-this, where "
[[...
]" means optional (depends on the kernel's
-configuration) and "{...}" is a comment.
-
-
-
-
-
-+-------------------------------+
-| arch/i386/boot/setup.S:: + |
-| arch/i386/boot/video.S:: |
-|-------------------------------|
-| start_of_setup: |
-| check that loaded OK |
-| get system memory size |
-| get video mode(s) |
-| get hard disk parameters |
-| get MC bus information |
-| get mouse information |
-| get APM BIOS information |
-| enable address line A20 |
-| reset coprocessor |
-| mask all interrupts |
-| move to protected mode |
-| jmp to startup_32 |
-+-------------------------------+
-|
-v
-+-------------------------------+
-| arch/i386/kernel/head.S:: |
-|-------------------------------|
-| startup_32: |
-| set segment registers to |
-| known values |
-| init basic page tables |
-| setup the stack pointer |
-| clear kernel BSS |
-| setup the IDT |
-| checkCPUtype |
-| load GDT, IDT, and LDT |
-| pointer registers |
-| start_kernel |
-| {it does not return} |
-+-------------------------------+
-|
-v
-+-------------------------------+ +-------------------------------+
-| init/main.c:: | +->| arch/i386/kernel/setup.c:: |
-|-------------------------------| | |-------------------------------|
-| start_kernel(): | | | setup_arch(): |
-| lock_kernel | | | copy boot parameters |
-| setup_arch |--+ | init ramdisk |
-| parse_options |<-+ | setup_memory_region |
-| trap_init | | | parse_cmd_line |
-| cpu_init | | | use the BIOS memory map to |
-| init_IRQ | | | setup page frame info. |
-| sched_init | | | reserve physical page 0 |
-| init_timervecs | | | [[find_smp_config] |
-| time_init | | | paging_init |
-| softirq_init | | | [[get_smp_config] |
-| console_init | | | [[init_apic_mappings] |
-| [[init_modules] | | | [[reserve INITRD memory] |
-| [[profiling setup] | | | probe_roms to search |
-| kmem_cache_init | | | for option ROMs |
-| sti | | | request_resource to |
-| calibrate_delay | | | reserve video RAM memory |
-| [[INITRD setup] | | | request_resource to |
-| mem_init | | | reserve all standard PC |
-| free_all_bootmem | +--| I/O system board resources|
-| kmem_cache_sizes_init | +-------------------------------+
-| [[proc_root_init] |
-| fork_init |
-| proc_caches_init |
-| vfs_caches_init |
-| buffer_init |
-| page_cache_init |
-| kiobuf_setup |
-| signals_init | +-------------------------------+
-| bdev_init | | init/main.c:: |
-| inode_init | | init(): {...init thread...} |
-| [[ipc_init] | | do_basic_setup |
-| [[dquot_init_hash] | | {bus/dev init & initcalls}|
-| check_bugs | | free_initmem |
-| [[smp_init] {*below} | | open /dev/console |
-| start init thread {---->} |.....| exec init script or shell |
-| unlock_kernel | | or panic |
-| cpu_idle | +-------------------------------+
-+-------------------------------+
-+-------------------------------+
-| smpboot.c::smp_init |
-|-------------------------------|
-| arch/i386/kernel/smpboot.c:: |
-| smp_boot_cpus(): |
-| [[mtrr_init_boot_cpu] |
-| smp_store_cpu_info |
-| print_cpu_info |
-| save CPU ID/APIC ID mappings|
-| verify_local_APIC |
-| connect_bsp_APIC |
-| setup_local_APIC |
-| foreach valid APIC ID |
-| do_boot_cpu(apicid) |
-| setup_IO_APIC |
-| setup_APIC_clocks |
-| synchronize_tsc_bp |
-+-------------------------------+
-
-
-
-
-
-
-
-
-----
-
-!!3. Linux early setup
-
-
-
-
-
-(from linux/arch/i386/boot/setup.S and linux/arch/i386/boot/video.S)
-
-
-NOTE: Register notation is %regname and constant notation is a number,
-with or without a leading '$' sign.
-
-
-
-
-!!3.1 IA-32 Kernel Setup
-
-
-
-
-
-
-"setup.S" is responsible for getting the system data from the BIOS
-and putting them into the appropriate places in system memory.
-
-
-Both "setup.S" and the kernel have been loaded by the boot block.
-
-
-"setup.S" is assembled as 16-bit real-mode code.
-It switches the processor to 32-bit protected mode and jumps to
-the 32-bit kernel code.
-
-
-This code asks the BIOS for memory/disk/other parameters, and
-puts them in a "safe" place: 0x90000-0x901FF, that is, where the
-boot block used to be. It is then up to the protected mode
-system to read them from there before the area is overwritten
-for buffer-blocks.
-
-
-The "setup.S" code begins with a jmp instruction around the
-"setup header", which must begin at location %cs:2.
-
-
-This is the setup header:
-
-
-
-
-----
-
-.ascii "HdrS" # header signature
-.word 0x0202 # header version number
-realmode_swtch: .word , 0 # default_switch, SETUPSEG
-start_sys_seg: .word SYSSEG
-.word kernel_version # pointer to kernel version string
-type_of_loader: .byte
-loadflags:
-LOADED_HIGH = 1 # If set, the kernel is loaded high
-#ifndef __BIG_KERNEL__
-.byte
-#else
-.byte LOADED_HIGH
-#endif
-setup_move_size: .word 0x8000 # size to move, when setup is not
-# loaded at 0x90000.
-code32_start: #
here loaders can put a different
-# start address for 32-bit code.
-#ifndef __BIG_KERNEL__
-.long 0x1000 # default for zImage
-#else
-.long 0x100000# default for big kernel
-#endif
-ramdisk_image: .long 0 # address of loaded ramdisk image
-ramdisk_size: .long 0 # its size in bytes
-bootsect_kludge: .word bootsect_helper, SETUPSEG
-heap_end_ptr: .word modelist+1024 # (Header version 0x0201 or later)
-# space from here (exclusive) down to
-# end of setup code can be used by setup
-# for local heap purposes.
-pad1: .word
-cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
-# If nonzero, a 32-bit pointer
-# to the kernel command line.
-trampoline: call start_of_setup # no return from start_of_setup
-.space 1024
-# End of setup header #####################################################
-
-----
-
-
-
-
-
-!start_of_setup:
-
-
-
-
-
-
-
-!Read second hard drive DASD type
-
-
-
-
-
-Read the DASD type of the second hard drive (BIOS int. 0x13,
-%ax=0x1500, %dl=0x81).
-
-
-# Bootlin depends on this being done early. [[TBD:why?]
-
-
-
-
-!Check that LILO loaded us right
-
-
-
-
-
-Check the signature words at the end of setup.
-Signature words are used to ensure that LILO loaded us right.
-If the two words are not found correctly, copy the
-setup sectors and check for the signature words again.
-If they still aren't found, panic("No setup signature found ...").
-
-
-
-
-!Check old loader trying to load a big kernel
-
-
-
-
-
-If the kernel image is "big" (and hence is "loaded high"), then
-if the loader cannot handle "loaded high" images, then
-panic ("Wrong loader, giving up...").
-
-
-
-
-
-
-
-!Determine system memory size
-
-
-
-
-
-Get the extended memory size {above 1 MB} in KB.
-First clear the extended memory size to .
-
-
-#ifndef STANDARD_MEMORY_BIOS_CALL
-
-
-Clear the E820 memory area counter.
-
-
-Try three different memory detection schemes.
-First, try E820h, which lets us assemble a memory map, then try E801h,
-which returns a 32-bit memory size, and finally 88h, which
-returns -64 MB.
-
-
-Method E820H populates a table in the empty_zero_block that contains
-a list of usable address/size/type tuples.
-In "linux/arch/i386/kernel/setup.c", this information is
-transferred into the e820map, and in "linux/arch/i386/mm/init.c", that
-new information is used to mark pages reserved or not.
-
-
-Method E820H:
-Get the BIOS memory map. E820h returns memory classified into
-different types and allows memory holes.
-We scan through this memory map and build a list of the first
-32 memory areas {up to 32 entries or BIOS says that there are no
-more entries}, which we return at "E820MAP".
-[[See URL: http://www.teleport.com/ acpi/acpihtml/topic245.htm]
-
-
-Method E801H:
-We store the 0xe801 memory size in a completely different place,
-because it will most likely be longer than 16 bits.
-
-
-This is the sum of 2 registers, normalized to 1 KB chunk sizes:
-%ecx = memory size from 1 MB to 16 MB range, in 1 KB chunks +
-%edx = memory size above 16 MB, in 64 KB chunks.
-
-
-Ye Olde Traditional Methode:
-BIOS int. 0x15/AH=0x88 returns the memory size (up to 16 MB or 64 MB,
-depending on the BIOS).
-We always use this method, regardless of the results of the other
-two methods.
-
-
-#endif
-
-
-Set the keyboard repeat rate to the maximum rate using
-using BIOS int. 0x16.
-
-
-
-
-!Video adapter modes
-
-
-
-
-
-Find the video adapter and its supported modes and allow the
-user to browse video modes.
-
-
-call video # {see Video section below}
-
-
-
-
-!Get Hard Disk parameters
-
-
-
-
-
-Get hd0 data:
-Save the hd0 descriptor (from int. vector 0x41) at INITSEG:0x80 length 0x10.
-
-
-Get hd1 data:
-Save the hd1 descriptor (from int. vector 0x46) at INITSEG:0x90 length 0x10.
-
-
-Check that there IS an hd1, using BIOS int. 0x13.
-If not, clear its descriptor.
-
-
-
-
-!Get Micro Channel bus information
-
-
-
-
-
-Check for Micro Channel (MCA) bus:
-
-
-* Set MCA feature table length to 0 in case not found.
-*
-
-* Get System Configuration Parameters (BIOS int. 0x15/%ah=0xc0).
-This sets %es:%bx to point to the system feature table.
-*
-
-* We keep only the first 16 bytes of the system feature table if found:
-Structure size, Model byte, Submodel byte, BIOS revision,
-and Feature information bytes 1-5.
-Bit 0 or 1 (either one) of Feature byte 1 indicates that the system
-contains a Micro Channel bus.
-*
-
-
-
-
-
-!Check for mouse
-
-
-
-
-
-Check for PS/2 pointing device by using BIOS int. 0x11 {get equipment list}.
-
-
-* Clear the pointing device flag (default).
-*
-
-* BIOS int. 0x11: get equipment list.
-*
-
-* If bit 2 (value 0x04) is set, then a mouse is installed and the
-pointing device flag is set to indicate that the device is present.
-*
-
-
-
-
-
-!Check for APM BIOS support
-
-
-
-
-
-Check for an APM BIOS (if kernel is configured for APM support):
-
-
-* start: clear version field to , which means no APM BIOS present.
-*
-
-* Check for APM BIOS installation using BIOS int. 0x15.
-*
-
-* If not present, done.
-*
-
-* Check for "PM" signature returned in %bx.
-*
-
-* If no signature, then no APM BIOS: done.
-*
-
-* Check for 32-bit support in %cx.
-*
-
-* If no 32-bit support, no (good) APM BIOS: done.
-Must have 32-bit APM BIOS support to be used by Linux.
-*
-
-* Save the BIOS code segment, BIOS entry point offset,
-BIOS 16-bit code segment, BIOS data segment,
-BIOS code segment length, and BIOS data segment length.
-*
-
-* Record the APM BIOS version and flags.
-*
-
-
-
-
-
-!Prepare to move to protected mode
-
-
-
-
-
-We build a jump instruction to the kernel's code32_start address.
-(The loader may have changed it.)
-
-
-Move the kernel to its correct place if necessary.
-
-
-Load the segment descriptors (load %ds = %cs).
-
-
-Make sure that we are at the right position in memory, to
-accommodate the command line and boot parameters at their
-fixed locations.
-
-
-Load the IDT pointer register with ,.
-
-
-Calculate the linear base address of the kernel GDT (table) and load the
-GDT pointer register with its base address and limit.
-This early kernel GDT describes kernel code as 4 GB, with base address ,
-code/readable/executable, with granularity of 4 KB.
-The kernel data segment is described as 4 GB, with base address ,
-data/readable/writable, with granularity of 4 KB.
-
-
-
-
-!Enable address line A20
-
-
-
-
-
-
-
-
-* Empty the 8042 (keyboard controller) of any queued keys.
-*
-
-* Write 0xd1 (Write Output Port) to Command Register port 0x64.
-*
-
-* Empty the 8042 (keyboard controller) of any queued keys.
-*
-
-* Write 0xdf (Gate A20 + more) to Output port 0x60.
-*
-
-* Empty the 8042 (keyboard controller) of any queued keys.
-*
-
-* Set bit number 1 (value 0x02: FAST_A20) in the "port 0x92"
-system control register. This enables A20 on some systems, depending
-on the chipset used in them.
-*
-
-* Wait until A20 really *is* enabled; it can take a fair amount of
-time on certain systems.
-The memory location used here (0x200) is the int 0x80
-vector, which should be safe to use.
-When A20 is disabled, the test memory locations are an alias
-of each other (segment :offset 0x200 and segment 0xffff:offset 0x210).
-{0xffff0 + 0x210 = 0x100200, but if A20 is disabled, this becomes
-0x000200.}
-We just wait (busy wait/loop) until these memory locations are
-no longer aliased.
-*
-
-
-
-
-
-!Make sure any possible coprocessor is properly reset
-
-
-
-
-
-
-
-
-* Write 0 to port 0xf0 to clear the Math Coprocessor '-busy' signal.
-*
-
-* Write 0 to port 0xf1 to reset the Math Coprocessor.
-*
-
-
-
-
-
-!Mask all interrupts
-
-
-
-
-
-Now we mask all interrupts; the rest is done in init_IRQ().
-
-
-
-
-
-* Mask off all interrupts on the slave PIC: write 0xff to port 0xa1.
-*
-
-* Mask off all interrupts on the master PIC except for IRQ2,
-which is the cascaded IRQ input from the slave PIC: write 0xfb to port 0x21.
-*
-
-
-
-
-
-!Move to Protected Mode
-
-
-
-
-
-Now is the time to actually move into protected mode. To make
-things as simple as possible, we do no register setup or anything,
-we let the GNU-compiled 32-bit programs do that. We just jump to
-absolute address 0x1000 (or the loader supplied one),
-in 32-bit protected mode.
-
-
-Note that the short jump isn't strictly needed, although there are
-reasons why it might be a good idea. It won't hurt in any case.
-
-
-Set the PE (Protected mode Enable) bit in the MSW and jump to the
-following instruction to flush the instruction fetch queue.
-
-
-Clear %bx to indicate that this is the BSP (first CPU only).
-
-
-
-
-!Jump to startup_32 code
-
-
-
-
-
-Jump to the 32-bit kernel code (startup_32).
-
-
-NOTE: For high-loaded big kernels we need:
-
-
-jmpi 0x100000,__KERNEL_CS
-
-
-but we yet haven't reloaded the %cs register, so the default size
-of the target offset still is 16 bit.
-However, using an operand prefix (0x66), the CPU will properly
-take our 48-bit far pointer. (INTeL 80386 Programmer's Reference
-Manual, Mixing 16-bit and 32-bit code, page 16-6).
-
-
-
-
-
-.byte 0x66, 0xea # prefix + jmpi-opcode
-code32: .long 0x1000 # or 0x100000 for big kernels
-.word __KERNEL_CS
-
-
-
-
-This jumps to "startup_32" in "linux/arch/i386/kernel/head.S".
-
-
-
-
-!!3.2 Video Setup
-
-
-
-
-
-
-"linux/arch/i386/boot/video.S" is included into
-"linux/arch/i386/boot/setup.S", so they are assembled together.
-The file separation is a logical module separation even though
-the two modules aren't built separately.
-
-
-"video.S" handles Linux/i386 display adapter and video mode setup.
-For more information about Linux/i386 video modes, see
-"linux/Documentation/svga.txt" by Martin Mares [[mj@ucw.cz].
-
-
-Video mode selection is a kernel build option. When it is
-enabled, You can select a specific (fixed) video mode to be used
-during kernel booting or you can ask to view a selection menu
-and then choose a video mode from that menu.
-
-
-There are a few esoteric (!) "video.S" build options that
-not covered here. See "linux/Documentation/svga.txt" for all
-of them.
-
-
-CONFIG_VIDEO_SVGA (for automatic detection of SVGA adapters and
-modes) is normally #undefined. The normal method of video
-adapter detection on Linux/i386 is VESA (CONFIG_VIDEO_VESA,
-for autodetection of VESA modes).
-
-
-"video:" is the main entry point called by "setup.S".
-The %ds register *must* be pointing to the bootsector.
-The "video.S" code uses different segments from the main "setup.S" code.
-
-
-This is a simplified description of the code flow in "video.S".
-It does not address the CONFIG_VIDEO_LOCAL, CONFIG_VIDEO_400_HACK,
-and CONFIG_VIDEO_GFX_HACK build options and it does not dive deep
-into video BIOS calls or video register accesses.
-
-
-
-
-!video:
-
-
-
-
-
-
-
-
-* %fs is set to the original %ds value
-*
-
-* %ds and %es are set to %cs
-*
-
-* %gs is set to zero
-*
-
-* Detect the video adapter type and supported modes. (call basic_detect)
-*
-
-* #ifdef CONFIG_VIDEO_SELECT
-*
-
-* If the user wants to see a list of the supported VGA adapter
-modes, list them. (call mode_menu)
-*
-
-* Set the selected video mode. (call mode_set)
-*
-
-* #ifdef CONFIG_VIDEO_RETAIN
-*
-
-* Restore the screen contents. (call restore_screen)
-*
-
-* #endif /* CONFIG_VIDEO_RETAIN */
-*
-
-* #endif /* CONFIG_VIDEO_SELECT */
-*
-
-* Store mode parameters for kernel. (call mode_params)
-*
-
-* Restore original DS register value.
-*
-
-
-
-
-
-!basic_detect:
-
-
-
-
-
-
-
-
-* Detect if we have CGA, MDA, HGA, EGA, or VGA and pass it to the kernel.
-*
-
-* Check for EGA/VGA using BIOS int. 0x10 calls.
-This also tells whether the video adapter is CGA/MDA/HGA.
-*
-
-* The "adapter" variable is returned as 0 for CGA/MDA/HGA, 1 for EGA,
-and 2 for VGA.
-*
-
-
-
-
-
-!mode_params:
-
-
-
-
-
-
-
-
-* Store the video mode parameters for later use by the kernel.
-This is done by asking the BIOS for mode parameters except for the
-rows/columns parameters in the default 80x25 mode -- these are set directly,
-because some very obscure BIOSes supply insane values.
-*
-
-* #ifdef CONFIG_VIDEO_SELECT
-*
-
-* For graphics mode with a linear frame buffer, goto mopar_gr.
-*
-
-* #endif /* CONFIG_VIDEO_SELECT */
-*
-
-* For MDA/CGA/HGA/EGA/VGA:
-*
-
-* Read and save cursor position.
-*
-
-* Read and save video page/mode/width.
-*
-
-* For MDA/HGA, change the video_segment to $0xb000.
-(Leave it at its initial value of $0xb800 for all other adapters.)
-*
-
-* Get the Font size (valid only on EGA/VGA).
-*
-
-* Save the number of video columns and lines.
-*
-
-
-
-#ifdef CONFIG_VIDEO_SELECT
-
-
-
-
-!mopar_gr:
-
-
-
-
-
-
-
-
-* Get VESA frame buffer parameters.
-*
-
-* Get video mem size and protected mode interface information
-using BIOS int. 0x10 calls.
-*
-
-
-
-
-
-!mode_menu:
-
-
-
-
-
-Build the mode list table and display the mode menu.
-
-
-
-
-!mode_set:
-
-
-
-
-
-For the selected video mode, use BIOS int. 0x10 calls or register
-writes as needed to set some or all of:
-
-
-* Reset the video mode
-*
-
-* Number of scan lines
-*
-
-* Font pixel size
-*
-
-* Save the screen size in force_size. "force_size" is used
-to override possibly broken video BIOS interfaces and is used
-instead of the BIOS variables.
-*
-
-
-
-Some video modes require register writes to set:
-
-
-* Location of the cursor scan lines
-*
-
-* Vertical sync start
-*
-
-* Vertical sync end
-*
-
-* Vertical display end
-*
-
-* Vertical blank start
-*
-
-* Vertical blank end
-*
-
-* Vertical total
-*
-
-* (Vertical) overflow
-*
-
-* Correct sync polarity
-*
-
-* Preserve clock select bits and color bit
-*
-
-
-
-{end of mode_set}
-
-
-#ifdef CONFIG_VIDEO_RETAIN /* Normally _IS_ #defined */
-
-
-
-
-!store_screen:
-
-
-
-
-
-CONFIG_VIDEO_RETAIN is used to retain screen contents when
-switching modes.
-This option stores the screen contents to a temporary memory buffer
-(if there is enough memory) so that they can be restored later.
-
-
-
-
-
-* Save the current number of video lines and columns,
-cursor position, and video mode.
-*
-
-* Calculate the image size.
-*
-
-* Save the screen image.
-*
-
-* Set the "do_restore" flag so that the screen contents
-will be restored at the end of video mode detection/selection.
-*
-
-
-
-
-
-!restore_screen:
-
-
-
-
-
-Restores screen contents from temporary buffer (if already saved).
-
-
-
-
-
-* Get parameters of current mode.
-*
-
-* Set cursor position.
-*
-
-* Restore the screen contents.
-*
-
-
-
-#endif /* CONFIG_VIDEO_RETAIN */
-
-
-
-
-!mode_table:
-
-
-
-
-
-Build the table of video modes at `modelist'.
-
-
-
-
-
-* Store standard modes.
-*
-
-* Add modes for standard VGA.
-*
-
-* #ifdef CONFIG_VIDEO_LOCAL
-*
-
-* Add locally-defined video modes. (call local_modes)
-*
-
-* #endif /* CONFIG_VIDEO_LOCAL */
-*
-
-* #ifdef CONFIG_VIDEO_VESA
-*
-
-* Auto-detect VESA VGA modes. (call vesa_modes)
-*
-
-* #endif /* CONFIG_VIDEO_VESA */
-*
-
-* #ifdef CONFIG_VIDEO_SVGA
-*
-
-* Detect SVGA cards & modes. (call svga_modes)
-*
-
-* #endif /* CONFIG_VIDEO_SVGA */
-*
-
-* #ifdef CONFIG_VIDEO_COMPACT
-*
-
-* Compact the video modes list, removing duplicate entries.
-*
-
-* #endif /* CONFIG_VIDEO_COMPACT */
-*
-
-
-
-
-
-!mode_scan:
-
-
-
-
-
-Scans for video modes.
-
-
-
-
-
-* Start with mode .
-*
-
-* Test the mode.
-*
-
-* Test if it's a text mode.
-*
-
-* OK, store the mode.
-*
-
-* Restore back to mode 3.
-*
-
-
-
-#ifdef CONFIG_VIDEO_SVGA
-
-
-
-
-!svga_modes:
-
-
-
-
-
-Try to detect the type of SVGA card and supply (usually approximate)
-video mode table for it.
-
-
-
-
-
-* Test all known SVGA adapters.
-*
-
-* Call the test routine for each adapter.
-*
-
-* If adapter is found, copy the video modes.
-*
-
-* Store pointer to card name.
-*
-
-
-
-#endif /* CONFIG_VIDEO_SVGA */
-
-
-#endif /* CONFIG_VIDEO_SELECT */
-
-
-
-----
-
-!!4. Linux architecture-specific initialization
-
-
-
-
-
-(from "linux/arch/i386/kernel/head.S")
-
-
-The boot code in "linux/arch/i386/boot/setup.S" transfers execution
-to the beginning code in "linux/arch/i386/kernel/head.S"
-(labeled "startup_32:").
-
-
-To get to this point, a small uncompressed kernel function
-decompresses the remaining compressed kernel image
-and then it jumps to the new kernel code.
-
-
-This is a description of what the "head.S" code does.
-
-
-
-
-!!4.1 startup_32:
-
-
-
-
-
-
-swapper_pg_dir is the top-level page directory, address 0x00101000.
-
-
-On entry, %esi points to the real-mode code as a 32-bit pointer.
-
-
-
-
-!!4.2 Set segment registers to known values
-
-
-
-
-
-
-Set the %ds, %es, %fs, and %gs registers to __KERNEL_DS.
-
-
-
-
-!!4.3 SMP BSP (Bootstrap Processor) check
-
-
-
-
-
-
-#ifdef CONFIG_SMP
-
-
-If %bx is zero, this is a boot on the Bootstrap Processor (BSP),
-so skip this. Otherwise, for an AP (Application Processor):
-
-
-If the desired %cr4 setting is non-zero, turn on the paging options
-(PSE, PAE, ...) and skip "Initialize page tables" (jump to "Enable paging").
-
-
-#endif /* CONFIG_SMP */
-
-
-
-
-!!4.4 Initialize page tables
-
-
-
-
-
-
-Begin at pg0 (page ) and init all pages to 007 (PRESENT + RW + USER).
-
-
-
-
-!!4.5 Enable paging
-
-
-
-
-
-
-Set %cr3 (page table pointer) to swapper_pg_dir.
-
-
-Set the paging ("PG") bit of %cr0 to
-__********** enable paging **********__.
-
-
-Jump $ to flush the prefetch queue.
-
-
-Jump *[[$] to make sure that %eip is relocated.
-
-
-Setup the stack pointer (lss stack_start, %esp).
-
-
-#ifdef CONFIG_SMP
-
-
-If this is not the BSP (Bootstrap Processor), clear all flags bits
-and jump to checkCPUtype.
-
-
-#endif /* CONFIG_SMP */
-
-
-
-
-!!4.6 Clear BSS
-
-
-
-
-
-
-The BSP clears all of BSS (area between __bss_start and _end)
-for the kernel.
-
-
-
-
-!!4.7 32-bit setup
-
-
-
-
-
-
-Setup the IDT for 32-bit mode (call setup_idt).
-setup_idt sets up an IDT with 256 entries pointing to the default
-interrupt handler "ignore_int" as interrupt gates. It doesn't actually
-load the IDT; that can be done only after paging has been enabled
-and the kernel moved to PAGE_OFFSET. Interrupts
-are enabled elsewhere, when we can be relatively
-sure everything is OK.
-
-
-Clear the eflags register (before switching to protected mode).
-
-
-
-
-!!4.8 Copy boot parameters and command line out of the way
-
-
-
-
-
-
-First 2 KB of _empty_zero_page is for boot parameters,
-second 2 KB is for the command line.
-
-
-
-
-!!4.9 checkCPUtype
-
-
-
-
-
-
-Initialize X86_CPUID to -1.
-
-
-Use Flags register, push/pop results, and CPUID instruction(s) to
-determine CPU type and vendor:
-Sets X86, X86_CPUID, X86_MODEL, X86_MASK, and X86_CAPABILITY.
-Sets bits in %cr0 accordingly.
-
-
-Also checks for presence of an 80287 or 80387 coprocessor.
-Sets X86_HARD_MATH if a math coprocessor or floating point unit is found.
-
-
-
-
-!!4.10 Count this processor
-
-
-
-
-
-
-For CONFIG_SMP builds, increment the "ready" counter to keep a tally
-of the number of CPUs that have been initialized.
-
-
-
-
-!!4.11 Load descriptor table pointer registers
-
-
-
-
-
-
-Load GDT with gdt_descr and IDT with idt_descr.
-The GDT contains 2 entries for the kernel (4 GB each for code and
-data, beginning at ) and 2 userspace entries (4 GB each for code and
-data, beginning at ). There are 2 null descriptors between the
-userspace descriptors and the APM descriptors.
-
-
-The GDT also contains 4 entries for APM segments.
-The APM segments have byte granularity and their bases and limits
-are set at runtime.
-
-
-The rest of the gdt_table (after the APM segments) is space for
-TSSes and LDTs.
-
-
-Jump to __KERNEL_CS:%eip to cause the GDT to be used. Now in
-__********** protected mode **********__.
-
-
-Reload all of the segment registers:
-Set the %ds, %es, %fs, and %gs registers to __KERNEL_DS.
-
-
-#ifdef CONFIG_SMP
-
-
-Reload the stack pointer segment only (%ss) with __KERNEL_DS.
-
-
-#else /* not CONFIG_SMP */
-
-
-Reload the stack pointer (%ss:%esp) with stack_start.
-
-
-#endif /* CONFIG_SMP */
-
-
-Clear the LDT pointer to .
-
-
-Clear the processor's Direction Flag (DF) to 0 for gcc.
-
-
-
-
-!!4.12 Start other processors
-
-
-
-
-
-
-For CONFIG_SMP builds,
-if this is not the first (Bootstrap) CPU, call initialize_secondary(),
-which does not return. The secondary (AP) processor(s) are
-initialized and then enter idle state until processes are
-scheduled on them.
-
-
-If this is the first or only CPU, call start_kernel(). (see below)
-
-
-/* the calls above should never return, but in case they do: */
-
-
-L6: jmp L6
-
-
-
-----
-
-!!5. Linux architecture-independent initialization
-
-
-
-
-
-(from "linux/init/main.c")
-
-
-"linux/init/main.c" begins execution with the start_kernel() function,
-which is called from "linux/arch/i386/kernel/head.S".
-start_kernel() never returns to its caller. It ends by calling the
-cpu_idle() function.
-
-
-
-
-!!5.1 start_kernel:
-
-
-
-
-
-
-Interrupts are still disabled. Do necessary setups, then enable them.
-
-
-Lock the kernel (BKL: big kernel lock).
-
-
-Print the linux_banner string (this string resides in "linux/init/version.c")
-using printk(). NOTE: printk() doesn't actually print this to the console
-yet; it just buffers the string until a console device registers itself with
-the kernel, then the kernel passes the buffered console log contents to the
-registered console device(s). There can be multiple registered console
-devices.
-
-
-********** printk() can be called very early because it doesn't actually
-print to anywhere. It just logs the message to "log_buf",
-which is allocated statically in "linux/kernel/printk.c".
-The messages that are saved in "log_buf" are passed to registered
-console devices as they register. **********
-
-
-
-
-!More architecture-specific init
-
-
-
-
-
-Call setup_arch(&command_line):
-
-
-This performs architecture-specific initializations
-(details below).
-Then back to architecture-independent initialization....
-
-
-The remainder of start_kernel() is done as follows for all
-processor architecures, although several of these function
-calls are to architecture-specific setup/init functions.
-
-
-
-
-!Continue architecture-independent init
-
-
-Print the kernel command line.
-
-
-
-
-!Parsing command line options
-
-
-
-
-
-parse_options(command_line):
-Parse the kernel options on the command line.
-This is a simple kernel command line parsing function. It parses the
-command line and fills in the arguments and environment to init (thread)
-as appropriate. Any command-line option is taken to be an environment
-variable if it contains the character '='.
-It also checks for options meant for the kernel by calling
-checksetup(), which checks the command line for kernel parameters,
-these being specified by declaring them using "__setup", as in:
-
-
-
-
-----
-
-__setup("debug", debug_kernel);
-
-----
-
-
-
-This declaration causes the debug_kernel() function to be
-called when the string "debug" is scanned.
-See "linux/Documentation/kernel-parameters.txt" for the list of
-kernel parameters.
-
-
-These options are not given to init -- they are for internal kernel
-use only. The default argument list for the init thread is
-{"init", NULL}, with a maximum of 8 command-line arguments.
-The default environment list for the init thread is
-{"HOME=/", "TERM=linux", NULL}, with a maximum of 8
-command-line environment variable settings.
-In case LILO is going to boot us with default command line,
-it prepends "auto" before the whole cmdline which makes
-the shell think it should execute a script with such name.
-So we ignore all arguments entered _before_ init=... [[MJ]
-
-
-
-
-!trap_init
-
-
-
-
-
-(in linux/arch/i386/kernel/traps.c)
-
-
-Install exception handlers for basic processor exceptions,
-i.e., not hardware device interrupt handlers.
-
-
-Install the handler for the system call software interrupt.
-
-
-Install handlers for lcall7 (for iBCS) and lcall27 (for
-Solaris/x86 binaries).
-
-
-Call cpu_init() to do:
-
-
-* initialize per-CPU state
-*
-
-* reload the GDT and IDT
-*
-
-* mask off the eflags NT (Nested Task) bit
-*
-
-* set up and load the per-CPU TSS and LDT
-*
-
-* clear 6 debug registers (, 1, 2, 3, 6, and 7)
-*
-
-* stts(): set the 0x08 bit (TS: Task Switched) in CR0 to enable
-lazy register saves on context switches
-*
-
-
-
-
-
-!init_IRQ
-
-
-
-
-
-(in linux/arch/i386/kernel/i8259.c)
-
-
-Call init_ISA_irqs() to initialize the two 8259A interrupt controllers
-and install default interrupt handlers for the ISA IRQs.
-
-
-Set an interrupt gate for all unused interrupt vectors.
-
-
-For CONFIG_SMP configurations, set up IRQ 0 early, since it's
-used before the IO APIC is set up.
-
-
-For CONFIG_SMP, install the interrupt handler for CPU-to-CPU
-IPIs that are used for the "reschedule helper."
-
-
-For CONFIG_SMP, install the interrupt handler for the IPI that is
-used to invalidate TLBs.
-
-
-For CONFIG_SMP, install the interrupt handler for the IPI that is
-used for generic function calls.
-
-
-For CONFIG_X86_LOCAL_APIC configurations, install the interrupt
-handler for the self-generated local APIC timer IPI.
-
-
-For CONFIG_X86_LOCAL_APIC configurations, install interrupt handlers
-for spurious and error interrupts.
-
-
-Set the system's clock chip to generate a timer tick interrupt
-every HZ Hz.
-
-
-If the system has an external FPU, set up IRQ 13 to handle
-floating point exceptions.
-
-
-
-
-!sched_init
-
-
-
-
-
-(in linux/kernel/sched.c)
-
-
-
-
-
-* Set the init_task's processor ID.
-*
-
-* Clear the pidhash table. TBD: Why? isn't it in BSS?
-*
-
-* call init_timervecs()
-*
-
-* call init_bh() to init "bottom half" queues for timer_bh,
-tqueue_bh, and immediate_bh.
-*
-
-
-
-
-
-!time_init
-
-
-
-
-
-(in linux/arch/i386/kernel/time.c)
-
-
-Initialize the system's current time of day (xtime) from CMOS.
-
-
-Install the irq0 timer tick interrupt handler.
-
-
-
-
-!softirq_init
-
-
-
-
-
-(in linux/kernel/softirq.c)
-
-
-
-
-!console_init
-
-
-
-
-
-(in linux/drivers/char/tty_io.c)
-
-
-HACK ALERT! This is early. We're enabling the console before
-we've done PCI setups etc., and console_init() must be aware of
-this. But we do want output early, in case something goes wrong.
-
-
-
-
-!init_modules
-
-
-
-
-
-(in linux/kernel/module.c)
-
-
-For CONFIG_MODULES configurations, call init_modules().
-This initializes the size (or number of symbols) of the kernel
-symbol table.
-
-
-
-
-!Profiling setup
-
-
-
-
-
-if profiling ("profile=#" on the kernel command line):
-calculate the kernel text (code) profile "segment" size;
-calculate the profile buffer size in pages (round up);
-allocate the profile buffer: prof_buffer = alloc_bootmem(size);
-
-
-
-
-!kmem_cache_init
-
-
-
-
-
-(in linux/mm/slab.c)
-
-
-
-
-!sti
-
-
-
-
-
-__********** Interrupts are now enabled. **********__
-This allows "calibrate_delay()" (below) to work.
-
-
-
-
-!calibrate_delay
-
-
-
-
-
-Calculate the "loops_per_jiffy" delay loop value and print
-it in BogoMIPS.
-
-
-
-
-!INITRD setup
-
-
-
-
-
-
-
-
-#ifdef CONFIG_BLK_DEV_INITRD
-if (initrd_start && !initrd_below_start_ok &&
-initrd_start < (min_low_pfn << PAGE_SHIFT)) {
-printk("initrd overwritten (initrd_start < (min_low_pfn << PAGE_SHIFT)) - disabling it.\n");
-initrd_start = ; // mark initrd as disabled
-}
-#endif /* CONFIG_BLK_DEV_INITRD */
-
-
-
-
-
-
-!mem_init
-
-
-
-
-
-(in linux/arch/i386/mm/init.c)
-
-
-
-
-
-* Clear the empty_zero_page.
-*
-
-* Call free_all_bootmem() and add that released memory to
-totalram_pages.
-*
-
-* Count the number of reserved RAM pages.
-*
-
-* Print the system memory sizes (free/total), kernel code size, reserved
-memory size, kernel data size, kernel "init" size, and the highmem
-size.
-*
-
-* For CONFIG_SMP, call zap_low_mappings().
-*
-
-
-
-********** get_free_pages() can be used after mem_init(). **********
-
-
-
-
-!kmem_cache_sizes_init
-
-
-
-
-
-(in linux/mm/slab.c)
-
-
-Set up remaining internal and general caches. Called after the
-"get_free_page()" functions have been enabled and before smp_init().
-
-
-********** kmalloc() can be used after kmem_cache_sizes_init(). **********
-
-
-
-
-!proc_root_init
-
-
-
-
-
-(in linux/fs/proc/root.c)
-
-
-For CONFIG_PROC_FS configurations:
-
-
-* call proc_misc_init()
-*
-
-* mkdir /proc/net
-*
-
-* for CONFIG_SYSVIPC, mkdir /proc/sysvipc
-*
-
-* for CONFIG_SYSCTL, mkdir /proc/sys
-*
-
-* mkdir /proc/fs
-*
-
-* mkdir /proc/driver
-*
-
-* call proc_tty_init()
-*
-
-* mkdir /proc/bus
-*
-
-
-
-
-
-!mempages = num_physpages;
-
-
-
-
-
-
-
-!fork_init(mempages)
-
-
-
-
-
-(in linux/kernel/fork.c)
-
-
-The default maximum number of threads is set to a safe value:
-the thread structures can take up at most half of memory.
-
-
-
-
-!proc_caches_init()
-
-
-
-
-
-(in linux/kernel/fork.c)
-
-
-Call kmem_cache_create() to create slab caches for signal_act (signal
-action), files_cache (files_struct), fs_cache (fs_struct), vm_area_struct,
-and mm_struct.
-
-
-
-
-!vfs_caches_init(mempages)
-
-
-
-
-
-(in linux/fs/dcache.c)
-
-
-Call kmem_cache_create() to create slab caches for buffer_head,
-names_cache, filp, and for CONFIG_QUOTA, dquot.
-
-
-Call dcache_init() to create the dentry_cache and dentry_hashtable.
-
-
-
-
-!buffer_init(mempages)
-
-
-
-
-
-(in linux/fs/buffer.c)
-
-
-Allocate the buffer cache hash table and init the free list.
-Use get_free_pages() for the hash table to decrease TLB misses;
-use SLAB cache for buffer heads.
-Setup the hash chains, free lists, and LRU lists.
-
-
-
-
-!page_cache_init(mempages)
-
-
-
-
-
-(in linux/mm/filemap.c)
-
-
-Allocate and clear the page-cache hash table.
-
-
-
-
-!kiobuf_setup()
-
-
-
-
-
-(in linux/fs/iobuf.c)
-
-
-Call kmem_cache_create() to create the kernel iobuf cache.
-
-
-
-
-!signals_init()
-
-
-
-
-
-(in linux/kernel/signal.c)
-
-
-Call kmem_cache_create() to create the "sigqueue" SLAB cache.
-
-
-
-
-!bdev_init()
-
-
-
-
-
-(in linux/fs/block_dev.c)
-
-
-Initialize the bdev_hashtable list heads.
-
-
-Call kmem_cache_create() to create the "bdev_cache" SLAB cache.
-
-
-
-
-!inode_init(mempages)
-
-
-
-
-
-(in linux/fs/inode.c)
-
-
-
-
-
-* Allocate memory for the inode_hashtable.
-*
-
-* Intialize the inode_hashtable list heads.
-*
-
-* Call kmem_cache_create() to create the inode SLAB cache.
-*
-
-
-
-
-
-!ipc_init()
-
-
-
-
-
-(in linux/ipc/util.c)
-
-
-For CONFIG_SYSVIPC configurations, call ipc_init().
-
-
-The various System V IPC resources (semaphores, messages, and shared
-memory) are initialized.
-
-
-
-
-!dquot_init_hash()
-
-
-
-
-
-(in linux/fs/dquot.c)
-
-
-For CONFIG_QUOTA configurations, call dquot_init_hash().
-
-
-
-
-
-* Clear dquot_hash. TBD: Why? Is it in BSS? Yes.
-*
-
-* Clear dqstats. TBD: Why? Is it in BSS? Yes.
-*
-
-
-
-
-
-!check_bugs()
-
-
-
-
-
-(in linux/include/asm-i386/bugs.h)
-
-
-
-
-
-* identify_cpu()
-*
-
-* For non-CONFIG_SMP configurations, print_cpu_info()
-*
-
-* check_config()
-*
-
-* check_fpu()
-*
-
-* check_hlt()
-*
-
-* check_popad()
-*
-
-* Update system_utsname.machine{byte 1} with boot_cpu_data.x86
-*
-
-
-
-
-
-!Start other SMP processors (as applicable)
-
-
-
-
-
-smp_init() works in one of three ways, depending upon the kernel
-configuration.
-
-
-For a uniprocessor (UP) system without an IO APIC
-(CONFIG_X86_IO_APIC is not defined), smp_init() is empty -- it
-has nothing to do.
-
-
-For a UP system with (an) IO APIC for interrupt
-routing, it calls IO_APIC_init_uniprocessor().
-
-
-For an SMP system, its main job is to call the architecture-specific
-function "smp_boot_cpus()", which does the following.
-
-
-
-
-
-* For CONFIG_MTRR kernels, calls mtrr_init_boot_cpu(), which must be
-done before the other processors are booted.
-*
-
-* Stores and prints the BSP CPU information.
-*
-
-* Saves the BSP APIC ID and BSP logical CPU ID (latter is ).
-*
-
-* If an MP BIOS interrupt routing table was not found, revert to
-using only one CPU and exit.
-*
-
-* Verify existence of a local APIC for the BSP.
-*
-
-* If the "maxcpus" boot option was used to limit the number of CPUs
-actually used to 1 (not SMP), then ignore the MP BIOS interrupt
-routing table.
-*
-
-* Switch the system from PIC mode to symmetric I/O interrupt mode.
-*
-
-* Setup the BSP's local APIC.
-*
-
-* Use the CPU present map to boot the APs serially. Wait for each
-AP to finish booting before starting the next one.
-*
-
-* If using (an) IO APIC {which is True unless the "noapic" boot option
-was used}, setup the IO APIC(s).
-*
-
-
-
-
-
-!Start init thread
-
-
-
-
-
-We count on the initial thread going OK.
-
-
-Like idlers, init is an unlocked kernel thread,
-which will make syscalls (and thus be locked).
-
-
-
-
-
-kernel_thread(init, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGNAL);
-
-
-
-
-{details below}
-
-
-
-
-!unlock_kernel()
-
-
-
-
-
-Release the BKL.
-
-
-
-
-!current->need_resched = 1;
-
-
-
-
-
-
-
-!cpu_idle()
-
-
-
-
-
-This function remains as process number . Its purpose is
-to use up idle CPU cycles. If the kernel is configured for
-APM support or ACPI support, cpu_idle() invokes the supported
-power-saving features of these specifications. Otherwise it
-nominally executes a "hlt" instruction.
-
-
-{end of start_kernel()}
-
-
-
-
-!!5.2 setup_arch
-
-
-
-
-
-
-(in "linux/arch/i386/kernel/setup.c")
-
-
-
-
-!Copy and convert system parameter data
-
-
-
-
-
-Copy and convert parameter data passed from 16-bit
-real mode to the 32-bit startup code.
-
-
-
-
-!For RAMdisk-enabled configs (CONFIG_BLK_DEV_RAM)
-
-
-
-
-
-Initialize rd_image_start, rd_prompt, and rd_doload from the
-real-mode parameter data.
-
-
-
-
-!setup_memory_region
-
-
-
-
-
-Use the BIOS-supplied memory map to setup memory regions.
-
-
-
-
-!Set memory limits
-
-
-
-
-
-Set values for the start of kernel code, end of kernel code,
-end of kernel data, and "_end" (end of kernel code = the "brk"
-address).
-
-
-Set values for code_resource start and end and data_resource
-start and end.
-
-
-
-
-!parse_mem_cmdline
-
-
-
-
-
-Parse any "mem=" parameters on the kernel command line and
-remember them.
-
-
-
-
-!Setup Page Frames
-
-
-
-
-
-Use the BIOS-supplied memory map to setup page frames.
-
-
-Register available low RAM pages with the bootmem allocator.
-
-
-Reserve physical page : "it's a special BIOS page on many boxes,
-enabling clean reboots, SMP operation, laptop functions."
-
-
-
-
-!Handle SMP and IO APIC Configurations
-
-
-
-
-
-For CONFIG_SMP, reserve the page immediately above page 0 for
-stack and trampoline usage, then call smp_alloc_memory()
-to allocate low memory for AP processor(s) real mode trampoline code.
-
-
-For CONFIG_X86_IO_APIC configurations, call find_smp_config()
-to find and reserve any boot-time SMP configuration information
-memory, such as MP (Multi Processor) table data from the BIOS.
-
-
-
-
-!paging_init()
-
-
-
-
-
-paging_init() sets up the page tables - note that the first 8 MB
-are already mapped by head.S.
-
-
-This routine also unmaps the page at virtual kernel address , so
-that we can trap those pesky NULL-reference errors in the kernel.
-
-
-
-
-!Save the boot-time SMP configuration
-
-
-
-
-
-For CONFIG_X86_IO_APIC configurations, call get_smp_config()
-to read and save the MP table IO APIC interrupt routing
-configuration data.
-
-
-For CONFIG_X86_LOCAL_APIC configurations, call init_apic_mappings().
-
-
-
-
-!Reserve INITRD memory
-
-
-
-
-
-For CONFIG_BLK_DEV_INITRD configurations, if there is enough
-memory for the initial !RamDisk, call reserve_bootmem() to
-reserve RAM for the initial !RamDisk.
-
-
-
-
-!Scan for option ROMs
-
-
-
-
-
-Call probe_roms() and reserve their memory space resource(s)
-if found and valid. This is done for the standard video BIOS
-ROM image, any option ROMs found, and for the system board
-extension ROM (space).
-
-
-
-
-!Reserve system resources
-
-
-
-
-
-Call request_resource() to reserve video RAM memory.
-
-
-Call request_resource() to reserve all standard PC I/O system board
-resources.
-
-
-{end of setup_arch()}
-
-
-
-
-!!5.3 init thread
-
-
-
-
-
-
-The init thread begins at the init() function in
-"linux/init/main.c". This is always expected to be process
-number 1.
-
-
-init() first locks the kernel and then calls do_basic_setup()
-to perform lots of bus and/or device initialization
-{more detail below}. After do_basic_setup(), most kernel
-initialization has been completed. init() then frees
-any memory that was specified as being for initialization
-only [[marked with "__init", "__initdata", "__init_call",
-or "__initsetup"] and unlocks the kernel (BKL).
-
-
-init() next opens /dev/console and duplicates that file
-descriptor two times to create stdin, stdout,
-and stderr files for init and all of its children.
-
-
-Finally init() tries to execute the command specified
-on the kernel parameters command line if there was one,
-or an init program or script if it can find one in
-{/sbin/init, /etc/init, /bin/init}, and lastly
-/bin/sh. If init() cannot execute any of these,
-it panics ("No init found. Try passing init= option to kernel.")
-
-
-
-
-!!5.4 do_basic_setup {part of the init thread}
-
-
-
-
-
-
-The machine is now initialized. None of the devices
-have been touched yet, but the CPU subsystem is up and
-running, and memory and process management works.
-
-
-
-
-!Be the reaper of orphaned children
-
-
-
-
-
-The init process handles all orphaned tasks.
-
-
-
-
-!MTRRs
-
-
-
-
-
-// SMP init is completed before this.
-For CONFIG_MTRR, call mtrr_init() [[in linux/arch/i386/kernel/mtrr.c].
-
-
-
-
-!SYSCTLs
-
-
-
-
-
-For CONFIG_SYSCTL configurations, call sysctl_init()
-[[in linux/kernel/sysctl.c].
-
-
-
-
-!Init Many Devices
-
-
-
-
-
-
-
-
-/*
-* Ok, at this point all CPU's should be initialized, so
-* we can start looking into devices..
-*/
-
-
-
-
-
-
-!PCI
-
-
-
-
-
-For CONFIG_PCI configurations, call pci_init()
-[[in linux/drivers/pci/pci.c].
-
-
-
-
-!Micro Channel
-
-
-
-
-
-For CONFIG_MCA configurations, call mca_init()
-[[in linux/arch/i386/kernel/mca.c].
-
-
-
-
-!ISA PnP
-
-
-
-
-
-For CONFIG_ISAPNP configurations, call isapnp_init()
-[[in linux/drivers/pnp/isapnp.c].
-
-
-
-
-!Networking Init
-
-
-
-
-
-
-
-
-/* Networking initialization needs a process context */
-sock_init();
-
-
-[[in linux/net/socket.c]
-
-
-
-
-!Initial !RamDisk
-
-
-
-
-
-
-
-
-#ifdef CONFIG_BLK_DEV_INITRD
-real_root_dev = ROOT_DEV;
-real_root_mountflags = root_mountflags;
-if (initrd_start && mount_initrd)
-root_mountflags &= ~MS_RDONLY; // change to read/write
-else
-mount_initrd =;
-#endif /* CONFIG_BLK_DEV_INITRD */
-
-
-
-
-
-
-!Start the kernel "context" thread (keventd)
-
-
-
-
-
-[[in linux/kernel/context.c]
-
-
-
-
-!Initcalls
-
-
-
-
-
-Call all functions marked as "__initcall":
-
-
-do_initcalls();
-
-
-[[in linux/init/main.c]
-
-
-This initializes many functions and some subsystems --- in no specific or
-guaranteed order unless fixed in their Makefiles --- if they were built
-into the kernel, such as:
-
-
-
-
-
-* APM: apm_init() {in linux/arch/i386/kernel/apm.c}
-*
-
-* cpuid: cpuid_init() {in linux/arch/i386/kernel/cpuid.c}
-*
-
-* DMI: dmi_scan_machine() {in linux/arch/i386/kernel/dmi_scan.c}
-*
-
-* microcode: microcode_init() {in linux/arch/i386/kernel/microcode.c}
-*
-
-* MSR: msr_init() {in linux/arch/i386/kernel/msr.c}
-*
-
-* partitions: partition_setup() {in linux/fs/partitions/check.s}
-*
-
-* file systems, pipes, buffer and cache management, various binary
-format loaders, NLS character sets:
-too numerous to list {in linux/fs/*}
-*
-
-* user cache (for limits): uid_cache_init() {in linux/kernel/user.c}
-*
-
-* kmem_cpu_cache: kmem_cpucache_init() {in linux/mm/slab.c}
-*
-
-* shmem: init_shmem_fs() {in linux/mm/shmem.c}
-*
-
-* kswapd: kswapd_init() {in linux/mm/vmscan.c}
-*
-
-* networking, TCP/IP, IPv6, sockets, 802.2, SNAP, LLC,
-X.25, AX.25, IPX, kHTTPd, ATM LAN emulation (LANE),
-IP chains/forwarding, NAT/masquerading, packet matching/filtering/logging,
-firewalling, DECnet, bridging,
-and other networking protocols too numerous to list {in linux/net/*}
-*
-
-* drivers, some of which are not exactly device drivers, but
-help out with bus/device enumeration and initialization, such as:
-*
-
-* ACPI: acpi_init() {in linux/drivers/acpi/*}
-*
-
-* PCI: pci_proc_init() {in linux/drivers/pci/*}
-*
-
-* PCMCIA controllers {in linux/drivers/pcmcia/*}
-*
-
-* and...
-*
-
-* atm drivers {in linux/drivers/atm/*}
-*
-
-* block drivers {in linux/drivers/block/*}
-*
-
-* CD-ROM drivers {in linux/drivers/cdrom/*}
-*
-
-* character drivers {in linux/drivers/char/*}
-*
-
-* I2O drivers {in linux/drivers/i2o/*}
-*
-
-* IDE drivers {in linux/drivers/ide/*}
-*
-
-* input drivers (keyboard/mouse/joystick) {in linux/drivers/input/*}
-*
-
-* ISDN drivers {in linux/drivers/isdn/*}
-*
-
-* md, LVM, and RAID drivers {in linux/drivers/md/*}
-*
-
-* radio drivers {in linux/drivers/media/radio/*}
-*
-
-* video drivers {in linux/drivers/media/video/*}
-*
-
-* MTD drivers {in linux/drivers/mtd/*}
-*
-
-* network drivers, including PLIP, PPP, dummy, Ethernet, bonding,
-Arcnet, hamradio, PCMCIA, Token Ring, and WAN
-*
-
-* SCSI logical and physical drivers {in linux/drivers/scsi/*}
-*
-
-* sound drivers {in linux/drivers/sound/*}
-*
-
-* telephony drivers {in linux/drivers/telephony/*}
-*
-
-* USB host controllers and device drivers {in linux/drivers/usb/*}
-*
-
-* video frame buffer drivers {in linux/drivers/video/*}
-*
-
-
-
-
-
-!Filesystems
-
-
-
-
-
-Call filesystem_setup():
-
-
-* init_devfs_fs(); /* Header file may make this empty */
-*
-
-* For CONFIG_NFS_FS configurations, call init_nfs_fs().
-*
-
-* For CONFIG_DEVPTS_FS configurations, call init_devpts_fs().
-*
-
-[[in linux/fs/filesystems.c]
-
-
-
-
-!IRDA
-
-
-
-
-
-For CONFIG_IRDA configurations, call irda_device_init().
-/* Must be done after protocol initialization */
-[[in linux/net/irda/irda_device.c]
-
-
-
-
-!PCMCIA
-
-
-
-
-
-/* Do this last */
-For CONFIG_PCMCIA configurations, call init_pcmcia_ds().
-[[in linux/drivers/pcmcia/ds.c]
-
-
-
-
-!Mount the root filesystem
-
-
-
-
-
-
-
-
-mount_root();
-
-
-[[in linux/fs/super.c]
-
-
-
-
-!Mount the dev (device) filesystem
-
-
-
-
-
-
-
-
-mount_devfs_fs ();
-
-
-[[in linux/fs/devfs/base.c]
-
-
-
-
-!Switch to the Initial !RamDisk
-
-
-
-
-
-
-
-
-#ifdef CONFIG_BLK_DEV_INITRD
-if (mount_initrd && MAJOR(ROOT_DEV) == RAMDISK_MAJOR && MINOR(ROOT_DEV) == ) {
-// Start the linuxrc thread.
-pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
-if (pid > )
-while (pid != wait(&i));
-if (MAJOR(real_root_dev) != RAMDISK_MAJOR
-|| MINOR(real_root_dev) != ) {
-error = change_root(real_root_dev,"/initrd");
-if (error)
-printk(KERN_ERR "Change root to /initrd: "
-"error %d\n",error);
-}
-}
-#endif /* CONFIG_BLK_DEV_INITRD */
-
-
-
-
-See "linux/Documentation/initrd.txt" for more information on
-initial RAM disks.
-
-
-{end of do_basic_setup()}
-
-
-
-----
-
-!!6. Glossary
-
-
-
-
-
-AP: Application Processor, any x86 processor other than the
-Bootstrap Processor on IA-32 SMP systems
-
-
-ACPI: Advanced Configuration and Power Interface
-
-
-APIC: Advanced Programmable Interrupt Controller
-
-
-APM: Advanced Power Management, a BIOS-managed power management
-specification for personal computers
-
-
-BSP: Bootstrap Processor, the primary booting processor on IA-32
-SMP systems
-
-
-BSS: Block Started by Symbol: the uninitialized data segment
-
-
-BKL: Big Kernel Lock, the Linux global kernel lock
-
-
-CRn: Control Register n, i386-specific control registers
-
-
-FPU: Floating Point Unit, a separate math coprocessor device
-
-
-GB: gigabyte (1024 * 1024 * 1024 bytes)
-
-
-GDT: Global Descriptor Table, an i386 memory management table
-
-
-IA: Intel Architecture (also i386, x86)
-
-
-IDT: Interrupt Descriptor Table, an i386-specific table that contains
-information used in handling interrupts
-
-
-initrd: initial RAM disk (see "linux/Documentation/initrd.txt")
-
-
-IPC: Inter-Process Communication
-
-
-IPI: Inter-processor Interrupt, a method of signaling interrupts
-between multiple processors on an SMP system
-
-
-IRDA: !InfraRed Data Association
-
-
-IRQ: Interrupt !ReQuest
-
-
-ISA: Industry Standard Architecture
-
-
-KB: kilobyte (1024 bytes)
-
-
-LDT: Local Descriptor Table, an i386-specific memory management table
-that is used to describe memory for each non-kernel process
-
-
-MB: megabyte (1024 * 1024 bytes)
-
-
-MCA: Micro Channel Architecture, used in IBM PS/2 computers
-
-
-MP: Multi-processor
-
-
-MSW: Machine Status Word
-
-
-MTRR: Memory Type Range Registers
-
-
-PAE: Physical Address Extension: extends the address space to 64 GB
-instead of 4 GB
-
-
-PCI: Peripheral Component Interconnect, an industry standard
-for connecting devices on a local bus in a computer system
-
-
-PCMCIA: Personal Computer Memory Card International Association;
-defines standards for PCMCIA cards and !CardBus PC Cards
-
-
-PIC: Programmable Interrupt Controller
-
-
-PNP: Plug aNd Play
-
-
-PSE: Page Size Extension: allows 4 MB pages
-
-
-SMP: Symmetric Multi Processor/Processing
-
-
-TLB: Translation Lookaside Buffer, i386-specific processor cache
-of recent page directory and page table entries
-
-
-TSS: Task State Segment, an i386-specific task data structure
-
-
-UP: Uniprocessor (single CPU) system.
-
-
-
-----
-
-!!7. References
-
-
-
-
-
-
-
-
-# Tigran Aivazian, "Linux Kernel Internals"
-(URL: http://www.moses.uklinux.net/patches/lki.html)
-#
-
-# Werner Almesberger, x86 Booting.
-(URL: ftp://icaftp.epfl.ch/pub/people/almesber/booting/)
-#
-
-# Werner Almesberger, "LILO Generic boot loader for Linux:
-Technical overview." December 4, 1998. Included in LILO distribution.
-#
-
-# Werner Almesberger and Hans Lermen, Using the initial RAM disk (initrd).
-(file: linux/Documentation/initrd.txt)
-#
-
-# H. Peter Anvin, "The Linux/I386 Boot Protocol (file:
-linux/Documentation/i386/boot.txt)
-#
-
-# Michael Beck et al, "Linux Kernel Internals," second edition.
-Addison-Wesley, 1998.
-#
-
-# Ralf Brown's Interrupt List,
-URL: http://www.ctyme.com/intr/int.htm {browsable}
-#
-
-# Ralf Brown's Interrupt List,
-URL: http://www.delorie.com/djgpp/doc/rbinter/ix/ {browsable}
-#
-
-# Ralf Brown's Interrupt List,
-URL: http://www.cs.cmu.edu/ ralf/files.html {zipped, not browsable}
-#
-
-# E820 memory sizing method:
-URL: http://www.teleport.com/ acpi/acpihtml/topic245.htm
-#
-
-# IBM Personal Computer AT Technical Reference. 1985.
-#
-
-# IBM Personal System/2(r) and Personal Computer BIOS Interface
-Technical Reference, second edition. 1988.
-#
-
-# Hans Lermen and Martin Mares, "Summary of empty_zero_page layout."
-(file: linux/Documentation/i386/zero-page.txt)
-#
-
-# linux/Documentation directory files
-#
-
-# Martin Mares, "Video Mode Selection Support." (file:
-linux/Documentation/svga.txt)
-#
-
-# Scott Maxwell, "Linux Core Kernel Commentary." Coriolis Press, 1999.
-#
-
-# Mindshare, Inc., Tom Shanley, "Pentium(r) Pro and Pentium(r) II
-System Architecture," second edition. Addison-Wesley, 1998.
-#
-
-# Allesandro Rubini, "Linux Device Drivers." O'Reilly and
-Associates, 1998.
-#
-
-# URL: ftp://linux01.gwdg.de/pub/cLIeNUX/interim/Janet_Reno.tgz
-#
-
-# URL: http://www.eecs.wsu.edu/~cs640/ (was dead at last check)
-#
-
-# URL: http://www.linuxbios
.org + "Papers"
-
-#
-
-
-
-
-----
+Describe
[HowToLinuxInitHOWTO
] here.
