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SubjectRe: [PATCH v3 02/27] Documentation: x86: convert boot.txt to reST
On Mon, May 06, 2019 at 02:52:58PM -0300, Mauro Carvalho Chehab wrote:
> Em Tue, 7 May 2019 01:08:58 +0800
> Changbin Du <changbin.du@gmail.com> escreveu:
>
> > This converts the plain text documentation to reStructuredText format and
> > add it to Sphinx TOC tree. No essential content change.
> >
> > Signed-off-by: Changbin Du <changbin.du@gmail.com>
> > Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
> > ---
> > Documentation/x86/{boot.txt => boot.rst} | 530 ++++++++++++++---------
> > Documentation/x86/index.rst | 2 +
> > 2 files changed, 329 insertions(+), 203 deletions(-)
> > rename Documentation/x86/{boot.txt => boot.rst} (73%)
> >
> > diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.rst
> > similarity index 73%
> > rename from Documentation/x86/boot.txt
> > rename to Documentation/x86/boot.rst
> > index 223e484a1304..5f20de0ced23 100644
> > --- a/Documentation/x86/boot.txt
> > +++ b/Documentation/x86/boot.rst
> > @@ -1,5 +1,8 @@
> > - THE LINUX/x86 BOOT PROTOCOL
> > - ---------------------------
> > +.. SPDX-License-Identifier: GPL-2.0
> > +
> > +===========================
> > +The Linux/x86 Boot Protocol
> > +===========================
> >
> > On the x86 platform, the Linux kernel uses a rather complicated boot
> > convention. This has evolved partially due to historical aspects, as
> > @@ -10,88 +13,91 @@ real-mode DOS as a mainstream operating system.
> >
> > Currently, the following versions of the Linux/x86 boot protocol exist.
> >
> > -Old kernels: zImage/Image support only. Some very early kernels
> > +============= ============================================================
> > +Old kernels zImage/Image support only. Some very early kernels
> > may not even support a command line.
> >
> > -Protocol 2.00: (Kernel 1.3.73) Added bzImage and initrd support, as
> > +Protocol 2.00 (Kernel 1.3.73) Added bzImage and initrd support, as
> > well as a formalized way to communicate between the
> > boot loader and the kernel. setup.S made relocatable,
> > although the traditional setup area still assumed
> > writable.
> >
> > -Protocol 2.01: (Kernel 1.3.76) Added a heap overrun warning.
> > +Protocol 2.01 (Kernel 1.3.76) Added a heap overrun warning.
> >
> > -Protocol 2.02: (Kernel 2.4.0-test3-pre3) New command line protocol.
> > +Protocol 2.02 (Kernel 2.4.0-test3-pre3) New command line protocol.
> > Lower the conventional memory ceiling. No overwrite
> > of the traditional setup area, thus making booting
> > safe for systems which use the EBDA from SMM or 32-bit
> > BIOS entry points. zImage deprecated but still
> > supported.
> >
> > -Protocol 2.03: (Kernel 2.4.18-pre1) Explicitly makes the highest possible
> > +Protocol 2.03 (Kernel 2.4.18-pre1) Explicitly makes the highest possible
> > initrd address available to the bootloader.
> >
> > -Protocol 2.04: (Kernel 2.6.14) Extend the syssize field to four bytes.
> > +Protocol 2.04 (Kernel 2.6.14) Extend the syssize field to four bytes.
> >
> > -Protocol 2.05: (Kernel 2.6.20) Make protected mode kernel relocatable.
> > +Protocol 2.05 (Kernel 2.6.20) Make protected mode kernel relocatable.
> > Introduce relocatable_kernel and kernel_alignment fields.
> >
> > -Protocol 2.06: (Kernel 2.6.22) Added a field that contains the size of
> > +Protocol 2.06 (Kernel 2.6.22) Added a field that contains the size of
> > the boot command line.
> >
> > -Protocol 2.07: (Kernel 2.6.24) Added paravirtualised boot protocol.
> > +Protocol 2.07 (Kernel 2.6.24) Added paravirtualised boot protocol.
> > Introduced hardware_subarch and hardware_subarch_data
> > and KEEP_SEGMENTS flag in load_flags.
> >
> > -Protocol 2.08: (Kernel 2.6.26) Added crc32 checksum and ELF format
> > +Protocol 2.08 (Kernel 2.6.26) Added crc32 checksum and ELF format
> > payload. Introduced payload_offset and payload_length
> > fields to aid in locating the payload.
> >
> > -Protocol 2.09: (Kernel 2.6.26) Added a field of 64-bit physical
> > +Protocol 2.09 (Kernel 2.6.26) Added a field of 64-bit physical
> > pointer to single linked list of struct setup_data.
> >
> > -Protocol 2.10: (Kernel 2.6.31) Added a protocol for relaxed alignment
> > +Protocol 2.10 (Kernel 2.6.31) Added a protocol for relaxed alignment
> > beyond the kernel_alignment added, new init_size and
> > pref_address fields. Added extended boot loader IDs.
> >
> > -Protocol 2.11: (Kernel 3.6) Added a field for offset of EFI handover
> > +Protocol 2.11 (Kernel 3.6) Added a field for offset of EFI handover
> > protocol entry point.
> >
> > -Protocol 2.12: (Kernel 3.8) Added the xloadflags field and extension fields
> > +Protocol 2.12 (Kernel 3.8) Added the xloadflags field and extension fields
> > to struct boot_params for loading bzImage and ramdisk
> > above 4G in 64bit.
> >
> > -Protocol 2.13: (Kernel 3.14) Support 32- and 64-bit flags being set in
> > +Protocol 2.13 (Kernel 3.14) Support 32- and 64-bit flags being set in
> > xloadflags to support booting a 64-bit kernel from 32-bit
> > EFI
> > +============= ============================================================
> >
> > -**** MEMORY LAYOUT
> >
> > -The traditional memory map for the kernel loader, used for Image or
> > -zImage kernels, typically looks like:
> > -
> > - | |
> > -0A0000 +------------------------+
> > - | Reserved for BIOS | Do not use. Reserved for BIOS EBDA.
> > -09A000 +------------------------+
> > - | Command line |
> > - | Stack/heap | For use by the kernel real-mode code.
> > -098000 +------------------------+
> > - | Kernel setup | The kernel real-mode code.
> > -090200 +------------------------+
> > - | Kernel boot sector | The kernel legacy boot sector.
> > -090000 +------------------------+
> > - | Protected-mode kernel | The bulk of the kernel image.
> > -010000 +------------------------+
> > - | Boot loader | <- Boot sector entry point 0000:7C00
> > -001000 +------------------------+
> > - | Reserved for MBR/BIOS |
> > -000800 +------------------------+
> > - | Typically used by MBR |
> > -000600 +------------------------+
> > - | BIOS use only |
> > -000000 +------------------------+
> > +Memory Layout
> > +=============
> >
> > +The traditional memory map for the kernel loader, used for Image or
> > +zImage kernels, typically looks like::
> > +
> > + | |
> > + 0A0000 +------------------------+
> > + | Reserved for BIOS | Do not use. Reserved for BIOS EBDA.
> > + 09A000 +------------------------+
> > + | Command line |
> > + | Stack/heap | For use by the kernel real-mode code.
> > + 098000 +------------------------+
> > + | Kernel setup | The kernel real-mode code.
> > + 090200 +------------------------+
> > + | Kernel boot sector | The kernel legacy boot sector.
> > + 090000 +------------------------+
> > + | Protected-mode kernel | The bulk of the kernel image.
> > + 010000 +------------------------+
> > + | Boot loader | <- Boot sector entry point 0000:7C00
> > + 001000 +------------------------+
> > + | Reserved for MBR/BIOS |
> > + 000800 +------------------------+
> > + | Typically used by MBR |
> > + 000600 +------------------------+
> > + | BIOS use only |
> > + 000000 +------------------------+
> >
> > When using bzImage, the protected-mode kernel was relocated to
> > 0x100000 ("high memory"), and the kernel real-mode block (boot sector,
> > @@ -116,36 +122,36 @@ zImage or old bzImage kernels, which need data written into the
> > above the 0x9A000 point; too many BIOSes will break above that point.
> >
> > For a modern bzImage kernel with boot protocol version >= 2.02, a
> > -memory layout like the following is suggested:
> > -
> > - ~ ~
> > - | Protected-mode kernel |
> > -100000 +------------------------+
> > - | I/O memory hole |
> > -0A0000 +------------------------+
> > - | Reserved for BIOS | Leave as much as possible unused
> > - ~ ~
> > - | Command line | (Can also be below the X+10000 mark)
> > -X+10000 +------------------------+
> > - | Stack/heap | For use by the kernel real-mode code.
> > -X+08000 +------------------------+
> > - | Kernel setup | The kernel real-mode code.
> > - | Kernel boot sector | The kernel legacy boot sector.
> > -X +------------------------+
> > - | Boot loader | <- Boot sector entry point 0000:7C00
> > -001000 +------------------------+
> > - | Reserved for MBR/BIOS |
> > -000800 +------------------------+
> > - | Typically used by MBR |
> > -000600 +------------------------+
> > - | BIOS use only |
> > -000000 +------------------------+
> > -
> > -... where the address X is as low as the design of the boot loader
> > -permits.
> > -
> > -
> > -**** THE REAL-MODE KERNEL HEADER
> > +memory layout like the following is suggested::
> > +
> > + ~ ~
> > + | Protected-mode kernel |
> > + 100000 +------------------------+
> > + | I/O memory hole |
> > + 0A0000 +------------------------+
> > + | Reserved for BIOS | Leave as much as possible unused
> > + ~ ~
> > + | Command line | (Can also be below the X+10000 mark)
> > + X+10000 +------------------------+
> > + | Stack/heap | For use by the kernel real-mode code.
> > + X+08000 +------------------------+
> > + | Kernel setup | The kernel real-mode code.
> > + | Kernel boot sector | The kernel legacy boot sector.
> > + X +------------------------+
> > + | Boot loader | <- Boot sector entry point 0000:7C00
> > + 001000 +------------------------+
> > + | Reserved for MBR/BIOS |
> > + 000800 +------------------------+
> > + | Typically used by MBR |
> > + 000600 +------------------------+
> > + | BIOS use only |
> > + 000000 +------------------------+
> > +
> > + ... where the address X is as low as the design of the boot loader permits.
> > +
> > +
> > +The Real-Mode Kernel Header
> > +===========================
> >
> > In the following text, and anywhere in the kernel boot sequence, "a
> > sector" refers to 512 bytes. It is independent of the actual sector
> > @@ -159,61 +165,63 @@ sectors (1K) and then examine the bootup sector size.
> >
> > The header looks like:
> >
> > -Offset Proto Name Meaning
> > -/Size
> > -
> > -01F1/1 ALL(1 setup_sects The size of the setup in sectors
> > -01F2/2 ALL root_flags If set, the root is mounted readonly
> > -01F4/4 2.04+(2 syssize The size of the 32-bit code in 16-byte paras
> > -01F8/2 ALL ram_size DO NOT USE - for bootsect.S use only
> > -01FA/2 ALL vid_mode Video mode control
> > -01FC/2 ALL root_dev Default root device number
> > -01FE/2 ALL boot_flag 0xAA55 magic number
> > -0200/2 2.00+ jump Jump instruction
> > -0202/4 2.00+ header Magic signature "HdrS"
> > -0206/2 2.00+ version Boot protocol version supported
> > -0208/4 2.00+ realmode_swtch Boot loader hook (see below)
> > -020C/2 2.00+ start_sys_seg The load-low segment (0x1000) (obsolete)
> > -020E/2 2.00+ kernel_version Pointer to kernel version string
> > -0210/1 2.00+ type_of_loader Boot loader identifier
> > -0211/1 2.00+ loadflags Boot protocol option flags
> > -0212/2 2.00+ setup_move_size Move to high memory size (used with hooks)
> > -0214/4 2.00+ code32_start Boot loader hook (see below)
> > -0218/4 2.00+ ramdisk_image initrd load address (set by boot loader)
> > -021C/4 2.00+ ramdisk_size initrd size (set by boot loader)
> > -0220/4 2.00+ bootsect_kludge DO NOT USE - for bootsect.S use only
> > -0224/2 2.01+ heap_end_ptr Free memory after setup end
> > -0226/1 2.02+(3 ext_loader_ver Extended boot loader version
> > -0227/1 2.02+(3 ext_loader_type Extended boot loader ID
> > -0228/4 2.02+ cmd_line_ptr 32-bit pointer to the kernel command line
> > -022C/4 2.03+ initrd_addr_max Highest legal initrd address
> > -0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel
> > -0234/1 2.05+ relocatable_kernel Whether kernel is relocatable or not
> > -0235/1 2.10+ min_alignment Minimum alignment, as a power of two
> > -0236/2 2.12+ xloadflags Boot protocol option flags
> > -0238/4 2.06+ cmdline_size Maximum size of the kernel command line
> > -023C/4 2.07+ hardware_subarch Hardware subarchitecture
> > -0240/8 2.07+ hardware_subarch_data Subarchitecture-specific data
> > -0248/4 2.08+ payload_offset Offset of kernel payload
> > -024C/4 2.08+ payload_length Length of kernel payload
> > -0250/8 2.09+ setup_data 64-bit physical pointer to linked list
> > - of struct setup_data
> > -0258/8 2.10+ pref_address Preferred loading address
> > -0260/4 2.10+ init_size Linear memory required during initialization
> > -0264/4 2.11+ handover_offset Offset of handover entry point
> > -
> > -(1) For backwards compatibility, if the setup_sects field contains 0, the
> > - real value is 4.
> > -
> > -(2) For boot protocol prior to 2.04, the upper two bytes of the syssize
> > - field are unusable, which means the size of a bzImage kernel
> > - cannot be determined.
> > -
> > -(3) Ignored, but safe to set, for boot protocols 2.02-2.09.
> > +=========== ======== ===================== ============================================
> > +Offset/Size Proto Name Meaning
> > +=========== ======== ===================== ============================================
> > +01F1/1 ALL(1) setup_sects The size of the setup in sectors
> > +01F2/2 ALL root_flags If set, the root is mounted readonly
> > +01F4/4 2.04+(2) syssize The size of the 32-bit code in 16-byte paras
> > +01F8/2 ALL ram_size DO NOT USE - for bootsect.S use only
> > +01FA/2 ALL vid_mode Video mode control
> > +01FC/2 ALL root_dev Default root device number
> > +01FE/2 ALL boot_flag 0xAA55 magic number
> > +0200/2 2.00+ jump Jump instruction
> > +0202/4 2.00+ header Magic signature "HdrS"
> > +0206/2 2.00+ version Boot protocol version supported
> > +0208/4 2.00+ realmode_swtch Boot loader hook (see below)
> > +020C/2 2.00+ start_sys_seg The load-low segment (0x1000) (obsolete)
> > +020E/2 2.00+ kernel_version Pointer to kernel version string
> > +0210/1 2.00+ type_of_loader Boot loader identifier
> > +0211/1 2.00+ loadflags Boot protocol option flags
> > +0212/2 2.00+ setup_move_size Move to high memory size (used with hooks)
> > +0214/4 2.00+ code32_start Boot loader hook (see below)
> > +0218/4 2.00+ ramdisk_image initrd load address (set by boot loader)
> > +021C/4 2.00+ ramdisk_size initrd size (set by boot loader)
> > +0220/4 2.00+ bootsect_kludge DO NOT USE - for bootsect.S use only
> > +0224/2 2.01+ heap_end_ptr Free memory after setup end
> > +0226/1 2.02+(3) ext_loader_ver Extended boot loader version
> > +0227/1 2.02+(3) ext_loader_type Extended boot loader ID
> > +0228/4 2.02+ cmd_line_ptr 32-bit pointer to the kernel command line
> > +022C/4 2.03+ initrd_addr_max Highest legal initrd address
> > +0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel
> > +0234/1 2.05+ relocatable_kernel Whether kernel is relocatable or not
> > +0235/1 2.10+ min_alignment Minimum alignment, as a power of two
> > +0236/2 2.12+ xloadflags Boot protocol option flags
> > +0238/4 2.06+ cmdline_size Maximum size of the kernel command line
> > +023C/4 2.07+ hardware_subarch Hardware subarchitecture
> > +0240/8 2.07+ hardware_subarch_data Subarchitecture-specific data
> > +0248/4 2.08+ payload_offset Offset of kernel payload
> > +024C/4 2.08+ payload_length Length of kernel payload
> > +0250/8 2.09+ setup_data 64-bit physical pointer to linked list
> > + of struct setup_data
> > +0258/8 2.10+ pref_address Preferred loading address
> > +0260/4 2.10+ init_size Linear memory required during initialization
> > +0264/4 2.11+ handover_offset Offset of handover entry point
> > +=========== ======== ===================== ============================================
> > +
> > +.. note::
> > + (1) For backwards compatibility, if the setup_sects field contains 0, the
> > + real value is 4.
> > +
> > + (2) For boot protocol prior to 2.04, the upper two bytes of the syssize
> > + field are unusable, which means the size of a bzImage kernel
> > + cannot be determined.
> > +
> > + (3) Ignored, but safe to set, for boot protocols 2.02-2.09.
> >
> > If the "HdrS" (0x53726448) magic number is not found at offset 0x202,
> > the boot protocol version is "old". Loading an old kernel, the
> > -following parameters should be assumed:
> > +following parameters should be assumed::
> >
> > Image type = zImage
> > initrd not supported
> > @@ -225,7 +233,8 @@ setting fields in the header, you must make sure only to set fields
> > supported by the protocol version in use.
> >
> >
> > -**** DETAILS OF HEADER FIELDS
> > +Details of Harder Fileds
> > +========================
> >
> > For each field, some are information from the kernel to the bootloader
> > ("read"), some are expected to be filled out by the bootloader
> > @@ -239,106 +248,132 @@ boot loaders can ignore those fields.
> >
> > The byte order of all fields is littleendian (this is x86, after all.)
> >
> > +============ ===========
> > Field name: setup_sects
> > Type: read
> > Offset/size: 0x1f1/1
> > Protocol: ALL
> > +============ ===========
> >
> > The size of the setup code in 512-byte sectors. If this field is
> > 0, the real value is 4. The real-mode code consists of the boot
> > sector (always one 512-byte sector) plus the setup code.
> >
> > -Field name: root_flags
> > -Type: modify (optional)
> > -Offset/size: 0x1f2/2
> > -Protocol: ALL
> > +============ =================
> > +Field name: root_flags
> > +Type: modify (optional)
> > +Offset/size: 0x1f2/2
> > +Protocol: ALL
> > +============ =================
> >
> > If this field is nonzero, the root defaults to readonly. The use of
> > this field is deprecated; use the "ro" or "rw" options on the
> > command line instead.
> >
> > +============ ===============================================
> > Field name: syssize
> > Type: read
> > Offset/size: 0x1f4/4 (protocol 2.04+) 0x1f4/2 (protocol ALL)
> > Protocol: 2.04+
> > +============ ===============================================
> >
> > The size of the protected-mode code in units of 16-byte paragraphs.
> > For protocol versions older than 2.04 this field is only two bytes
> > wide, and therefore cannot be trusted for the size of a kernel if
> > the LOAD_HIGH flag is set.
> >
> > +============ ===============
> > Field name: ram_size
> > Type: kernel internal
> > Offset/size: 0x1f8/2
> > Protocol: ALL
> > +============ ===============
> >
> > This field is obsolete.
> >
> > +============ ===================
> > Field name: vid_mode
> > Type: modify (obligatory)
> > Offset/size: 0x1fa/2
> > +============ ===================
> >
> > Please see the section on SPECIAL COMMAND LINE OPTIONS.
> >
> > +============ =================
> > Field name: root_dev
> > Type: modify (optional)
> > Offset/size: 0x1fc/2
> > Protocol: ALL
> > +============ =================
> >
> > The default root device device number. The use of this field is
> > deprecated, use the "root=" option on the command line instead.
> >
> > +============ =========
> > Field name: boot_flag
> > Type: read
> > Offset/size: 0x1fe/2
> > Protocol: ALL
> > +============ =========
> >
> > Contains 0xAA55. This is the closest thing old Linux kernels have
> > to a magic number.
> >
> > +============ =======
> > Field name: jump
> > Type: read
> > Offset/size: 0x200/2
> > Protocol: 2.00+
> > +============ =======
> >
> > Contains an x86 jump instruction, 0xEB followed by a signed offset
> > relative to byte 0x202. This can be used to determine the size of
> > the header.
> >
> > +============ =======
> > Field name: header
> > Type: read
> > Offset/size: 0x202/4
> > Protocol: 2.00+
> > +============ =======
> >
> > Contains the magic number "HdrS" (0x53726448).
> >
> > +============ =======
> > Field name: version
> > Type: read
> > Offset/size: 0x206/2
> > Protocol: 2.00+
> > +============ =======
> >
> > Contains the boot protocol version, in (major << 8)+minor format,
> > e.g. 0x0204 for version 2.04, and 0x0a11 for a hypothetical version
> > 10.17.
> >
> > +============ =================
> > Field name: realmode_swtch
> > Type: modify (optional)
> > Offset/size: 0x208/4
> > Protocol: 2.00+
> > +============ =================
> >
> > Boot loader hook (see ADVANCED BOOT LOADER HOOKS below.)
> >
> > +============ =============
> > Field name: start_sys_seg
> > Type: read
> > Offset/size: 0x20c/2
> > Protocol: 2.00+
> > +============ =============
> >
> > The load low segment (0x1000). Obsolete.
> >
> > +============ ==============
> > Field name: kernel_version
> > Type: read
> > Offset/size: 0x20e/2
> > Protocol: 2.00+
> > +============ ==============
> >
> > If set to a nonzero value, contains a pointer to a NUL-terminated
> > human-readable kernel version number string, less 0x200. This can
> > @@ -348,17 +383,21 @@ Protocol: 2.00+
> > For example, if this value is set to 0x1c00, the kernel version
> > number string can be found at offset 0x1e00 in the kernel file.
> > This is a valid value if and only if the "setup_sects" field
> > - contains the value 15 or higher, as:
> > + contains the value 15 or higher, as::
> >
> > 0x1c00 < 15*0x200 (= 0x1e00) but
> > 0x1c00 >= 14*0x200 (= 0x1c00)
> >
> > - 0x1c00 >> 9 = 14, so the minimum value for setup_secs is 15.
> > + 0x1c00 >> 9 = 14
> > +
> > + So the minimum value for setup_secs is 15.
>
> IMO, this belongs to the literal block.
>
ok.

> >
> > +============ ==================
> > Field name: type_of_loader
> > Type: write (obligatory)
> > Offset/size: 0x210/1
> > Protocol: 2.00+
> > +============ ==================
> >
> > If your boot loader has an assigned id (see table below), enter
> > 0xTV here, where T is an identifier for the boot loader and V is
> > @@ -369,17 +408,20 @@ Protocol: 2.00+
> > Similarly, the ext_loader_ver field can be used to provide more than
> > four bits for the bootloader version.
> >
> > - For example, for T = 0x15, V = 0x234, write:
> > + For example, for T = 0x15, V = 0x234, write::
> >
> > - type_of_loader <- 0xE4
> > - ext_loader_type <- 0x05
> > - ext_loader_ver <- 0x23
> > + type_of_loader <- 0xE4
> > + ext_loader_type <- 0x05
> > + ext_loader_ver <- 0x23
> >
> > Assigned boot loader ids (hexadecimal):
> >
> > - 0 LILO (0x00 reserved for pre-2.00 bootloader)
> > + == ==============================
>
> The table markup line here is too short.
>
> > + 0 LILO
> > + (0x00 reserved for pre-2.00 bootloader)
> > 1 Loadlin
> > - 2 bootsect-loader (0x20, all other values reserved)
> > + 2 bootsect-loader
> > + (0x20, all other values reserved)
> > 3 Syslinux
> > 4 Etherboot/gPXE/iPXE
> > 5 ELILO
> > @@ -390,55 +432,70 @@ Protocol: 2.00+
> > B Qemu
> > C Arcturus Networks uCbootloader
> > D kexec-tools
> > - E Extended (see ext_loader_type)
> > - F Special (0xFF = undefined)
> > - 10 Reserved
> > - 11 Minimal Linux Bootloader <http://sebastian-plotz.blogspot.de>
> > - 12 OVMF UEFI virtualization stack
> > + E Extended (see ext_loader_type)
> > + F Special (0xFF = undefined)
> > + 10 Reserved
> > + 11 Minimal Linux Bootloader
> > + <http://sebastian-plotz.blogspot.de>
> > + 12 OVMF UEFI virtualization stack
> > + == ==============================
>
> Same here: extending the line above will require extending it here too.
>
Fixed. Thanks.

> With the above changes:
>
> Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
>
>
> >
> > - Please contact <hpa@zytor.com> if you need a bootloader ID
> > - value assigned.
> > + 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 1 (kernel internal): KASLR_FLAG
> > +
> > - Used internally by the compressed kernel to communicate
> > KASLR status to kernel proper.
> > - If 1, KASLR enabled.
> > - If 0, KASLR disabled.
> > +
> > + - If 1, KASLR enabled.
> > + - If 0, KASLR disabled.
> >
> > Bit 5 (write): QUIET_FLAG
> > +
> > - If 0, print early messages.
> > - If 1, suppress early messages.
> > +
> > This requests to the kernel (decompressor and early
> > kernel) to not write early messages that require
> > accessing the display hardware directly.
> >
> > Bit 6 (write): KEEP_SEGMENTS
> > +
> > Protocol: 2.07+
> > +
> > - If 0, reload the segment registers in the 32bit entry point.
> > - If 1, do not reload the segment registers in the 32bit entry point.
> > +
> > Assume that %cs %ds %ss %es are all set to flat segments with
> > a base of 0 (or the equivalent for their environment).
> >
> > 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
> > @@ -447,14 +504,16 @@ Protocol: 2.00-2.01
> > 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
> > @@ -462,47 +521,57 @@ Protocol: 2.00+
> >
> > This field can be modified for two purposes:
> >
> > - 1. as a boot loader hook (see ADVANCED BOOT LOADER HOOKS below.)
> > + 1. as a boot loader hook (see Advanced Boot Loader Hooks below.)
> >
> > - 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.
> > + 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: ext_loader_ver
> > Type: write (optional)
> > Offset/size: 0x226/1
> > Protocol: 2.02+
> > +============ ================
> >
> > This field is used as an extension of the version number in the
> > type_of_loader field. The total version number is considered to be
> > @@ -514,10 +583,12 @@ Protocol: 2.02+
> > Kernels prior to 2.6.31 did not recognize this field, but it is safe
> > to write for protocol version 2.02 or higher.
> >
> > +============ =====================================================
> > Field name: ext_loader_type
> > Type: write (obligatory if (type_of_loader & 0xf0) == 0xe0)
> > Offset/size: 0x227/1
> > Protocol: 2.02+
> > +============ =====================================================
> >
> > This field is used as an extension of the type number in
> > type_of_loader field. If the type in type_of_loader is 0xE, then
> > @@ -528,10 +599,12 @@ Protocol: 2.02+
> > Kernels prior to 2.6.31 did not recognize this field, but it is safe
> > to write for protocol version 2.02 or higher.
> >
> > +============ ==================
> > 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
> > @@ -544,10 +617,12 @@ Protocol: 2.02+
> > 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
> > @@ -556,10 +631,12 @@ Protocol: 2.03+
> > 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/modify (reloc)
> > Offset/size: 0x230/4
> > Protocol: 2.05+ (read), 2.10+ (modify)
> > +============ ============================
> >
> > Alignment unit required by the kernel (if relocatable_kernel is
> > true.) A relocatable kernel that is loaded at an alignment
> > @@ -571,25 +648,29 @@ Protocol: 2.05+ (read), 2.10+ (modify)
> > loader to modify this field to permit a lesser alignment. See the
> > min_alignment and pref_address field below.
> >
> > +============ ==================
> > 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: min_alignment
> > Type: read (reloc)
> > Offset/size: 0x235/1
> > Protocol: 2.10+
> > +============ =============
> >
> > This field, if nonzero, indicates as a power of two the minimum
> > alignment required, as opposed to preferred, by the kernel to boot.
> > If a boot loader makes use of this field, it should update the
> > - kernel_alignment field with the alignment unit desired; typically:
> > + kernel_alignment field with the alignment unit desired; typically::
> >
> > kernel_alignment = 1 << min_alignment
> >
> > @@ -597,44 +678,56 @@ Protocol: 2.10+
> > misaligned kernel. Therefore, a loader should typically try each
> > power-of-two alignment from kernel_alignment down to this alignment.
> >
> > -Field name: xloadflags
> > -Type: read
> > -Offset/size: 0x236/2
> > -Protocol: 2.12+
> > +============ ==========
> > +Field name: xloadflags
> > +Type: read
> > +Offset/size: 0x236/2
> > +Protocol: 2.12+
> > +============ ==========
> >
> > This field is a bitmask.
> >
> > Bit 0 (read): XLF_KERNEL_64
> > +
> > - If 1, this kernel has the legacy 64-bit entry point at 0x200.
> >
> > Bit 1 (read): XLF_CAN_BE_LOADED_ABOVE_4G
> > +
> > - If 1, kernel/boot_params/cmdline/ramdisk can be above 4G.
> >
> > Bit 2 (read): XLF_EFI_HANDOVER_32
> > +
> > - If 1, the kernel supports the 32-bit EFI handoff entry point
> > given at handover_offset.
> >
> > Bit 3 (read): XLF_EFI_HANDOVER_64
> > +
> > - If 1, the kernel supports the 64-bit EFI handoff entry point
> > given at handover_offset + 0x200.
> >
> > Bit 4 (read): XLF_EFI_KEXEC
> > +
> > - If 1, the kernel supports kexec EFI boot with EFI runtime support.
> >
> > +
> > +============ ============
> > 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.
> >
> > +============ ====================================
> > Field name: hardware_subarch
> > Type: write (optional, defaults to x86/PC)
> > Offset/size: 0x23c/4
> > Protocol: 2.07+
> > +============ ====================================
> >
> > In a paravirtualized environment the hardware low level architectural
> > pieces such as interrupt handling, page table handling, and
> > @@ -643,25 +736,31 @@ Protocol: 2.07+
> > This field allows the bootloader to inform the kernel we are in one
> > one of those environments.
> >
> > + ========== ==============================
> > 0x00000000 The default x86/PC environment
> > 0x00000001 lguest
> > 0x00000002 Xen
> > 0x00000003 Moorestown MID
> > 0x00000004 CE4100 TV Platform
> > + ========== ==============================
> >
> > +============ =========================
> > Field name: hardware_subarch_data
> > Type: write (subarch-dependent)
> > Offset/size: 0x240/8
> > Protocol: 2.07+
> > +============ =========================
> >
> > A pointer to data that is specific to hardware subarch
> > This field is currently unused for the default x86/PC environment,
> > do not modify.
> >
> > +============ ==============
> > Field name: payload_offset
> > Type: read
> > Offset/size: 0x248/4
> > Protocol: 2.08+
> > +============ ==============
> >
> > If non-zero then this field contains the offset from the beginning
> > of the protected-mode code to the payload.
> > @@ -674,29 +773,33 @@ Protocol: 2.08+
> > 02 21). The uncompressed payload is currently always ELF (magic
> > number 7F 45 4C 46).
> >
> > +============ ==============
> > Field name: payload_length
> > Type: read
> > Offset/size: 0x24c/4
> > Protocol: 2.08+
> > +============ ==============
> >
> > The length of the payload.
> >
> > +============ ===============
> > Field name: setup_data
> > Type: write (special)
> > Offset/size: 0x250/8
> > Protocol: 2.09+
> > +============ ===============
> >
> > The 64-bit physical pointer to NULL terminated single linked list of
> > struct setup_data. This is used to define a more extensible boot
> > parameters passing mechanism. The definition of struct setup_data is
> > - as follow:
> > + as follow::
> >
> > - struct setup_data {
> > - u64 next;
> > - u32 type;
> > - u32 len;
> > - u8 data[0];
> > - };
> > + struct setup_data {
> > + u64 next;
> > + u32 type;
> > + u32 len;
> > + u8 data[0];
> > + };
> >
> > Where, the next is a 64-bit physical pointer to the next node of
> > linked list, the next field of the last node is 0; the type is used
> > @@ -708,10 +811,12 @@ Protocol: 2.09+
> > sure to consider the case where the linked list already contains
> > entries.
> >
> > +============ ============
> > Field name: pref_address
> > Type: read (reloc)
> > Offset/size: 0x258/8
> > Protocol: 2.10+
> > +============ ============
> >
> > This field, if nonzero, represents a preferred load address for the
> > kernel. A relocating bootloader should attempt to load at this
> > @@ -720,9 +825,11 @@ Protocol: 2.10+
> > A non-relocatable kernel will unconditionally move itself and to run
> > at this address.
> >
> > +============ =======
> > Field name: init_size
> > Type: read
> > Offset/size: 0x260/4
> > +============ =======
> >
> > This field indicates the amount of linear contiguous memory starting
> > at the kernel runtime start address that the kernel needs before it
> > @@ -731,16 +838,18 @@ Offset/size: 0x260/4
> > be used by a relocating boot loader to help select a safe load
> > address for the kernel.
> >
> > - The kernel runtime start address is determined by the following algorithm:
> > + The kernel runtime start address is determined by the following algorithm::
> >
> > - if (relocatable_kernel)
> > + if (relocatable_kernel)
> > runtime_start = align_up(load_address, kernel_alignment)
> > - else
> > + else
> > runtime_start = pref_address
> >
> > +============ ===============
> > Field name: handover_offset
> > Type: read
> > Offset/size: 0x264/4
> > +============ ===============
> >
> > This field is the offset from the beginning of the kernel image to
> > the EFI handover protocol entry point. Boot loaders using the EFI
> > @@ -749,7 +858,8 @@ Offset/size: 0x264/4
> > See EFI HANDOVER PROTOCOL below for more details.
> >
> >
> > -**** THE IMAGE CHECKSUM
> > +The Image Checksum
> > +==================
> >
> > From boot protocol version 2.08 onwards the CRC-32 is calculated over
> > the entire file using the characteristic polynomial 0x04C11DB7 and an
> > @@ -758,7 +868,8 @@ file; therefore the CRC of the file up to the limit specified in the
> > syssize field of the header is always 0.
> >
> >
> > -**** THE KERNEL COMMAND LINE
> > +The Kernel Command Line
> > +=======================
> >
> > The kernel command line has become an important way for the boot
> > loader to communicate with the kernel. Some of its options are also
> > @@ -778,19 +889,20 @@ heap and 0xA0000.
> > If the protocol version is *not* 2.02 or higher, the kernel
> > command line is entered using the following protocol:
> >
> > - At offset 0x0020 (word), "cmd_line_magic", enter the magic
> > - number 0xA33F.
> > + - At offset 0x0020 (word), "cmd_line_magic", enter the magic
> > + number 0xA33F.
> > +
> > + - At offset 0x0022 (word), "cmd_line_offset", enter the offset
> > + of the kernel command line (relative to the start of the
> > + real-mode kernel).
> >
> > - At offset 0x0022 (word), "cmd_line_offset", enter the offset
> > - of the kernel command line (relative to the start of the
> > - real-mode kernel).
> > -
> > - The kernel command line *must* be within the memory region
> > - covered by setup_move_size, so you may need to adjust this
> > - field.
> > + - The kernel command line *must* be within the memory region
> > + covered by setup_move_size, so you may need to adjust this
> > + field.
> >
> >
> > -**** MEMORY LAYOUT OF THE REAL-MODE CODE
> > +Memory Layout of The Real-Mode Code
> > +===================================
> >
> > The real-mode code requires a stack/heap to be set up, as well as
> > memory allocated for the kernel command line. This needs to be done
> > @@ -806,10 +918,11 @@ segment has to be used:
> > - When loading a zImage kernel ((loadflags & 0x01) == 0).
> > - When loading a 2.01 or earlier boot protocol kernel.
> >
> > - -> For the 2.00 and 2.01 boot protocols, the real-mode code
> > - can be loaded at another address, but it is internally
> > - relocated to 0x90000. For the "old" protocol, the
> > - real-mode code must be loaded at 0x90000.
> > +.. note::
> > + For the 2.00 and 2.01 boot protocols, the real-mode code
> > + can be loaded at another address, but it is internally
> > + relocated to 0x90000. For the "old" protocol, the
> > + real-mode code must be loaded at 0x90000.
> >
> > When loading at 0x90000, avoid using memory above 0x9a000.
> >
> > @@ -822,24 +935,29 @@ The kernel command line should not be located below the real-mode
> > code, nor should it be located in high memory.
> >
> >
> > -**** SAMPLE BOOT CONFIGURATION
> > +Sample Boot Configuartion
> > +=========================
> >
> > As a sample configuration, assume the following layout of the real
> > -mode segment:
> > +mode segment.
> >
> > When loading below 0x90000, use the entire segment:
> >
> > + ============= ===================
> > 0x0000-0x7fff Real mode kernel
> > 0x8000-0xdfff Stack and heap
> > 0xe000-0xffff Kernel command line
> > + ============= ===================
> >
> > When loading at 0x90000 OR the protocol version is 2.01 or earlier:
> >
> > + ============= ===================
> > 0x0000-0x7fff Real mode kernel
> > 0x8000-0x97ff Stack and heap
> > 0x9800-0x9fff Kernel command line
> > + ============= ===================
> >
> > -Such a boot loader should enter the following fields in the header:
> > +Such a boot loader should enter the following fields in the header::
> >
> > unsigned long base_ptr; /* base address for real-mode segment */
> >
> > @@ -898,7 +1016,8 @@ Such a boot loader should enter the following fields in the header:
> > }
> >
> >
> > -**** LOADING THE REST OF THE KERNEL
> > +Loading The Rest of The Kernel
> > +==============================
> >
> > The 32-bit (non-real-mode) kernel starts at offset (setup_sects+1)*512
> > in the kernel file (again, if setup_sects == 0 the real value is 4.)
> > @@ -906,7 +1025,7 @@ It should be loaded at address 0x10000 for Image/zImage kernels and
> > 0x100000 for bzImage kernels.
> >
> > The kernel is a bzImage kernel if the protocol >= 2.00 and the 0x01
> > -bit (LOAD_HIGH) in the loadflags field is set:
> > +bit (LOAD_HIGH) in the loadflags field is set::
> >
> > is_bzImage = (protocol >= 0x0200) && (loadflags & 0x01);
> > load_address = is_bzImage ? 0x100000 : 0x10000;
> > @@ -916,8 +1035,8 @@ the entire 0x10000-0x90000 range of memory. This means it is pretty
> > much a requirement for these kernels to load the real-mode part at
> > 0x90000. bzImage kernels allow much more flexibility.
> >
> > -
> > -**** SPECIAL COMMAND LINE OPTIONS
> > +Special Command Line Options
> > +============================
> >
> > If the command line provided by the boot loader is entered by the
> > user, the user may expect the following command line options to work.
> > @@ -966,7 +1085,8 @@ or configuration-specified command line. Otherwise, "init=/bin/sh"
> > gets confused by the "auto" option.
> >
> >
> > -**** RUNNING THE KERNEL
> > +Running the Kernel
> > +==================
> >
> > The kernel is started by jumping to the kernel entry point, which is
> > located at *segment* offset 0x20 from the start of the real mode
> > @@ -980,7 +1100,7 @@ interrupts should be disabled. Furthermore, to guard against bugs in
> > the kernel, it is recommended that the boot loader sets fs = gs = ds =
> > es = ss.
> >
> > -In our example from above, we would do:
> > +In our example from above, we would do::
> >
> > /* Note: in the case of the "old" kernel protocol, base_ptr must
> > be == 0x90000 at this point; see the previous sample code */
> > @@ -1003,7 +1123,8 @@ switched off, especially if the loaded kernel has the floppy driver as
> > a demand-loaded module!
> >
> >
> > -**** ADVANCED BOOT LOADER HOOKS
> > +Advanced Boot Loader Hooks
> > +==========================
> >
> > If the boot loader runs in a particularly hostile environment (such as
> > LOADLIN, which runs under DOS) it may be impossible to follow the
> > @@ -1032,7 +1153,8 @@ IMPORTANT: All the hooks are required to preserve %esp, %ebp, %esi and
> > (relocated, if appropriate.)
> >
> >
> > -**** 32-bit BOOT PROTOCOL
> > +32-bit Boot Protocol
> > +====================
> >
> > For machine with some new BIOS other than legacy BIOS, such as EFI,
> > LinuxBIOS, etc, and kexec, the 16-bit real mode setup code in kernel
> > @@ -1045,7 +1167,7 @@ traditionally known as "zero page"). The memory for struct boot_params
> > should be allocated and initialized to all zero. Then the setup header
> > from offset 0x01f1 of kernel image on should be loaded into struct
> > boot_params and examined. The end of setup header can be calculated as
> > -follow:
> > +follow::
> >
> > 0x0202 + byte value at offset 0x0201
> >
> > @@ -1069,7 +1191,8 @@ must have read/write permission; CS must be __BOOT_CS and DS, ES, SS
> > must be __BOOT_DS; interrupt must be disabled; %esi must hold the base
> > address of the struct boot_params; %ebp, %edi and %ebx must be zero.
> >
> > -**** 64-bit BOOT PROTOCOL
> > +64-bit Boot Protocol
> > +====================
> >
> > For machine with 64bit cpus and 64bit kernel, we could use 64bit bootloader
> > and we need a 64-bit boot protocol.
> > @@ -1080,7 +1203,7 @@ traditionally known as "zero page"). The memory for struct boot_params
> > could be allocated anywhere (even above 4G) and initialized to all zero.
> > Then, the setup header at offset 0x01f1 of kernel image on should be
> > loaded into struct boot_params and examined. The end of setup header
> > -can be calculated as follows:
> > +can be calculated as follows::
> >
> > 0x0202 + byte value at offset 0x0201
> >
> > @@ -1107,7 +1230,8 @@ must have read/write permission; CS must be __BOOT_CS and DS, ES, SS
> > must be __BOOT_DS; interrupt must be disabled; %rsi must hold the base
> > address of the struct boot_params.
> >
> > -**** EFI HANDOVER PROTOCOL
> > +EFI Handover Protocol
> > +=====================
> >
> > This protocol allows boot loaders to defer initialisation to the EFI
> > boot stub. The boot loader is required to load the kernel/initrd(s)
> > @@ -1115,7 +1239,7 @@ from the boot media and jump to the EFI handover protocol entry point
> > which is hdr->handover_offset bytes from the beginning of
> > startup_{32,64}.
> >
> > -The function prototype for the handover entry point looks like this,
> > +The function prototype for the handover entry point looks like this::
> >
> > efi_main(void *handle, efi_system_table_t *table, struct boot_params *bp)
> >
> > @@ -1124,11 +1248,11 @@ firmware, 'table' is the EFI system table - these are the first two
> > arguments of the "handoff state" as described in section 2.3 of the
> > UEFI specification. 'bp' is the boot loader-allocated boot params.
> >
> > -The boot loader *must* fill out the following fields in bp,
> > +The boot loader *must* fill out the following fields in bp::
> >
> > - o hdr.code32_start
> > - o hdr.cmd_line_ptr
> > - o hdr.ramdisk_image (if applicable)
> > - o hdr.ramdisk_size (if applicable)
> > + - hdr.code32_start
> > + - hdr.cmd_line_ptr
> > + - hdr.ramdisk_image (if applicable)
> > + - hdr.ramdisk_size (if applicable)
> >
> > All other fields should be zero.
> > diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst
> > index 9f34545a9c52..d7fc8efac192 100644
> > --- a/Documentation/x86/index.rst
> > +++ b/Documentation/x86/index.rst
> > @@ -7,3 +7,5 @@ x86-specific Documentation
> > .. toctree::
> > :maxdepth: 2
> > :numbered:
> > +
> > + boot
>
>
>
> Thanks,
> Mauro

--
Cheers,
Changbin Du

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