| Binman Entry Documentation |
| =========================== |
| |
| This file describes the entry types supported by binman. These entry types can |
| be placed in an image one by one to build up a final firmware image. It is |
| fairly easy to create new entry types. Just add a new file to the 'etype' |
| directory. You can use the existing entries as examples. |
| |
| Note that some entries are subclasses of others, using and extending their |
| features to produce new behaviours. |
| |
| |
| |
| Entry: blob: Entry containing an arbitrary binary blob |
| ------------------------------------------------------ |
| |
| Note: This should not be used by itself. It is normally used as a parent |
| class by other entry types. |
| |
| Properties / Entry arguments: |
| - filename: Filename of file to read into entry |
| - compress: Compression algorithm to use: |
| none: No compression |
| lz4: Use lz4 compression (via 'lz4' command-line utility) |
| |
| This entry reads data from a file and places it in the entry. The |
| default filename is often specified specified by the subclass. See for |
| example the 'u_boot' entry which provides the filename 'u-boot.bin'. |
| |
| If compression is enabled, an extra 'uncomp-size' property is written to |
| the node (if enabled with -u) which provides the uncompressed size of the |
| data. |
| |
| |
| |
| Entry: blob-dtb: A blob that holds a device tree |
| ------------------------------------------------ |
| |
| This is a blob containing a device tree. The contents of the blob are |
| obtained from the list of available device-tree files, managed by the |
| 'state' module. |
| |
| |
| |
| Entry: blob-named-by-arg: A blob entry which gets its filename property from its subclass |
| ----------------------------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - <xxx>-path: Filename containing the contents of this entry (optional, |
| defaults to 0) |
| |
| where <xxx> is the blob_fname argument to the constructor. |
| |
| This entry cannot be used directly. Instead, it is used as a parent class |
| for another entry, which defined blob_fname. This parameter is used to |
| set the entry-arg or property containing the filename. The entry-arg or |
| property is in turn used to set the actual filename. |
| |
| See cros_ec_rw for an example of this. |
| |
| |
| |
| Entry: cros-ec-rw: A blob entry which contains a Chromium OS read-write EC image |
| -------------------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - cros-ec-rw-path: Filename containing the EC image |
| |
| This entry holds a Chromium OS EC (embedded controller) image, for use in |
| updating the EC on startup via software sync. |
| |
| |
| |
| Entry: files: Entry containing a set of files |
| --------------------------------------------- |
| |
| Properties / Entry arguments: |
| - pattern: Filename pattern to match the files to include |
| - compress: Compression algorithm to use: |
| none: No compression |
| lz4: Use lz4 compression (via 'lz4' command-line utility) |
| |
| This entry reads a number of files and places each in a separate sub-entry |
| within this entry. To access these you need to enable device-tree updates |
| at run-time so you can obtain the file positions. |
| |
| |
| |
| Entry: fill: An entry which is filled to a particular byte value |
| ---------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - fill-byte: Byte to use to fill the entry |
| |
| Note that the size property must be set since otherwise this entry does not |
| know how large it should be. |
| |
| You can often achieve the same effect using the pad-byte property of the |
| overall image, in that the space between entries will then be padded with |
| that byte. But this entry is sometimes useful for explicitly setting the |
| byte value of a region. |
| |
| |
| |
| Entry: fmap: An entry which contains an Fmap section |
| ---------------------------------------------------- |
| |
| Properties / Entry arguments: |
| None |
| |
| FMAP is a simple format used by flashrom, an open-source utility for |
| reading and writing the SPI flash, typically on x86 CPUs. The format |
| provides flashrom with a list of areas, so it knows what it in the flash. |
| It can then read or write just a single area, instead of the whole flash. |
| |
| The format is defined by the flashrom project, in the file lib/fmap.h - |
| see www.flashrom.org/Flashrom for more information. |
| |
| When used, this entry will be populated with an FMAP which reflects the |
| entries in the current image. Note that any hierarchy is squashed, since |
| FMAP does not support this. |
| |
| |
| |
| Entry: gbb: An entry which contains a Chromium OS Google Binary Block |
| --------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - hardware-id: Hardware ID to use for this build (a string) |
| - keydir: Directory containing the public keys to use |
| - bmpblk: Filename containing images used by recovery |
| |
| Chromium OS uses a GBB to store various pieces of information, in particular |
| the root and recovery keys that are used to verify the boot process. Some |
| more details are here: |
| |
| https://www.chromium.org/chromium-os/firmware-porting-guide/2-concepts |
| |
| but note that the page dates from 2013 so is quite out of date. See |
| README.chromium for how to obtain the required keys and tools. |
| |
| |
| |
| Entry: intel-cmc: Entry containing an Intel Chipset Micro Code (CMC) file |
| ------------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of file to read into entry |
| |
| This file contains microcode for some devices in a special format. An |
| example filename is 'Microcode/C0_22211.BIN'. |
| |
| See README.x86 for information about x86 binary blobs. |
| |
| |
| |
| Entry: intel-descriptor: Intel flash descriptor block (4KB) |
| ----------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| filename: Filename of file containing the descriptor. This is typically |
| a 4KB binary file, sometimes called 'descriptor.bin' |
| |
| This entry is placed at the start of flash and provides information about |
| the SPI flash regions. In particular it provides the base address and |
| size of the ME (Management Engine) region, allowing us to place the ME |
| binary in the right place. |
| |
| With this entry in your image, the position of the 'intel-me' entry will be |
| fixed in the image, which avoids you needed to specify an offset for that |
| region. This is useful, because it is not possible to change the position |
| of the ME region without updating the descriptor. |
| |
| See README.x86 for information about x86 binary blobs. |
| |
| |
| |
| Entry: intel-fsp: Entry containing an Intel Firmware Support Package (FSP) file |
| ------------------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of file to read into entry |
| |
| This file contains binary blobs which are used on some devices to make the |
| platform work. U-Boot executes this code since it is not possible to set up |
| the hardware using U-Boot open-source code. Documentation is typically not |
| available in sufficient detail to allow this. |
| |
| An example filename is 'FSP/QUEENSBAY_FSP_GOLD_001_20-DECEMBER-2013.fd' |
| |
| See README.x86 for information about x86 binary blobs. |
| |
| |
| |
| Entry: intel-me: Entry containing an Intel Management Engine (ME) file |
| ---------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of file to read into entry |
| |
| This file contains code used by the SoC that is required to make it work. |
| The Management Engine is like a background task that runs things that are |
| not clearly documented, but may include keyboard, deplay and network |
| access. For platform that use ME it is not possible to disable it. U-Boot |
| does not directly execute code in the ME binary. |
| |
| A typical filename is 'me.bin'. |
| |
| See README.x86 for information about x86 binary blobs. |
| |
| |
| |
| Entry: intel-mrc: Entry containing an Intel Memory Reference Code (MRC) file |
| ---------------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of file to read into entry |
| |
| This file contains code for setting up the SDRAM on some Intel systems. This |
| is executed by U-Boot when needed early during startup. A typical filename |
| is 'mrc.bin'. |
| |
| See README.x86 for information about x86 binary blobs. |
| |
| |
| |
| Entry: intel-vbt: Entry containing an Intel Video BIOS Table (VBT) file |
| ----------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of file to read into entry |
| |
| This file contains code that sets up the integrated graphics subsystem on |
| some Intel SoCs. U-Boot executes this when the display is started up. |
| |
| See README.x86 for information about Intel binary blobs. |
| |
| |
| |
| Entry: intel-vga: Entry containing an Intel Video Graphics Adaptor (VGA) file |
| ----------------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of file to read into entry |
| |
| This file contains code that sets up the integrated graphics subsystem on |
| some Intel SoCs. U-Boot executes this when the display is started up. |
| |
| This is similar to the VBT file but in a different format. |
| |
| See README.x86 for information about Intel binary blobs. |
| |
| |
| |
| Entry: powerpc-mpc85xx-bootpg-resetvec: PowerPC mpc85xx bootpg + resetvec code for U-Boot |
| ----------------------------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot-br.bin (default 'u-boot-br.bin') |
| |
| This enrty is valid for PowerPC mpc85xx cpus. This entry holds |
| 'bootpg + resetvec' code for PowerPC mpc85xx CPUs which needs to be |
| placed at offset 'RESET_VECTOR_ADDRESS - 0xffc'. |
| |
| |
| |
| Entry: section: Entry that contains other entries |
| ------------------------------------------------- |
| |
| Properties / Entry arguments: (see binman README for more information) |
| - size: Size of section in bytes |
| - align-size: Align size to a particular power of two |
| - pad-before: Add padding before the entry |
| - pad-after: Add padding after the entry |
| - pad-byte: Pad byte to use when padding |
| - sort-by-offset: Reorder the entries by offset |
| - end-at-4gb: Used to build an x86 ROM which ends at 4GB (2^32) |
| - name-prefix: Adds a prefix to the name of every entry in the section |
| when writing out the map |
| |
| A section is an entry which can contain other entries, thus allowing |
| hierarchical images to be created. See 'Sections and hierarchical images' |
| in the binman README for more information. |
| |
| |
| |
| Entry: text: An entry which contains text |
| ----------------------------------------- |
| |
| The text can be provided either in the node itself or by a command-line |
| argument. There is a level of indirection to allow multiple text strings |
| and sharing of text. |
| |
| Properties / Entry arguments: |
| text-label: The value of this string indicates the property / entry-arg |
| that contains the string to place in the entry |
| <xxx> (actual name is the value of text-label): contains the string to |
| place in the entry. |
| |
| Example node: |
| |
| text { |
| size = <50>; |
| text-label = "message"; |
| }; |
| |
| You can then use: |
| |
| binman -amessage="this is my message" |
| |
| and binman will insert that string into the entry. |
| |
| It is also possible to put the string directly in the node: |
| |
| text { |
| size = <8>; |
| text-label = "message"; |
| message = "a message directly in the node" |
| }; |
| |
| The text is not itself nul-terminated. This can be achieved, if required, |
| by setting the size of the entry to something larger than the text. |
| |
| |
| |
| Entry: u-boot: U-Boot flat binary |
| --------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot.bin (default 'u-boot.bin') |
| |
| This is the U-Boot binary, containing relocation information to allow it |
| to relocate itself at runtime. The binary typically includes a device tree |
| blob at the end of it. Use u_boot_nodtb if you want to package the device |
| tree separately. |
| |
| U-Boot can access binman symbols at runtime. See: |
| |
| 'Access to binman entry offsets at run time (fdt)' |
| |
| in the binman README for more information. |
| |
| |
| |
| Entry: u-boot-dtb: U-Boot device tree |
| ------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot.dtb (default 'u-boot.dtb') |
| |
| This is the U-Boot device tree, containing configuration information for |
| U-Boot. U-Boot needs this to know what devices are present and which drivers |
| to activate. |
| |
| Note: This is mostly an internal entry type, used by others. This allows |
| binman to know which entries contain a device tree. |
| |
| |
| |
| Entry: u-boot-dtb-with-ucode: A U-Boot device tree file, with the microcode removed |
| ----------------------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot.dtb (default 'u-boot.dtb') |
| |
| See Entry_u_boot_ucode for full details of the three entries involved in |
| this process. This entry provides the U-Boot device-tree file, which |
| contains the microcode. If the microcode is not being collated into one |
| place then the offset and size of the microcode is recorded by this entry, |
| for use by u_boot_with_ucode_ptr. If it is being collated, then this |
| entry deletes the microcode from the device tree (to save space) and makes |
| it available to u_boot_ucode. |
| |
| |
| |
| Entry: u-boot-elf: U-Boot ELF image |
| ----------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot (default 'u-boot') |
| |
| This is the U-Boot ELF image. It does not include a device tree but can be |
| relocated to any address for execution. |
| |
| |
| |
| Entry: u-boot-img: U-Boot legacy image |
| -------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot.img (default 'u-boot.img') |
| |
| This is the U-Boot binary as a packaged image, in legacy format. It has a |
| header which allows it to be loaded at the correct address for execution. |
| |
| You should use FIT (Flat Image Tree) instead of the legacy image for new |
| applications. |
| |
| |
| |
| Entry: u-boot-nodtb: U-Boot flat binary without device tree appended |
| -------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot.bin (default 'u-boot-nodtb.bin') |
| |
| This is the U-Boot binary, containing relocation information to allow it |
| to relocate itself at runtime. It does not include a device tree blob at |
| the end of it so normally cannot work without it. You can add a u_boot_dtb |
| entry after this one, or use a u_boot entry instead (which contains both |
| U-Boot and the device tree). |
| |
| |
| |
| Entry: u-boot-spl: U-Boot SPL binary |
| ------------------------------------ |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot-spl.bin (default 'spl/u-boot-spl.bin') |
| |
| This is the U-Boot SPL (Secondary Program Loader) binary. This is a small |
| binary which loads before U-Boot proper, typically into on-chip SRAM. It is |
| responsible for locating, loading and jumping to U-Boot. Note that SPL is |
| not relocatable so must be loaded to the correct address in SRAM, or written |
| to run from the correct address if direct flash execution is possible (e.g. |
| on x86 devices). |
| |
| SPL can access binman symbols at runtime. See: |
| |
| 'Access to binman entry offsets at run time (symbols)' |
| |
| in the binman README for more information. |
| |
| The ELF file 'spl/u-boot-spl' must also be available for this to work, since |
| binman uses that to look up symbols to write into the SPL binary. |
| |
| |
| |
| Entry: u-boot-spl-bss-pad: U-Boot SPL binary padded with a BSS region |
| --------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| None |
| |
| This is similar to u_boot_spl except that padding is added after the SPL |
| binary to cover the BSS (Block Started by Symbol) region. This region holds |
| the various used by SPL. It is set to 0 by SPL when it starts up. If you |
| want to append data to the SPL image (such as a device tree file), you must |
| pad out the BSS region to avoid the data overlapping with U-Boot variables. |
| This entry is useful in that case. It automatically pads out the entry size |
| to cover both the code, data and BSS. |
| |
| The ELF file 'spl/u-boot-spl' must also be available for this to work, since |
| binman uses that to look up the BSS address. |
| |
| |
| |
| Entry: u-boot-spl-dtb: U-Boot SPL device tree |
| --------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot.dtb (default 'spl/u-boot-spl.dtb') |
| |
| This is the SPL device tree, containing configuration information for |
| SPL. SPL needs this to know what devices are present and which drivers |
| to activate. |
| |
| |
| |
| Entry: u-boot-spl-elf: U-Boot SPL ELF image |
| ------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of SPL u-boot (default 'spl/u-boot') |
| |
| This is the U-Boot SPL ELF image. It does not include a device tree but can |
| be relocated to any address for execution. |
| |
| |
| |
| Entry: u-boot-spl-nodtb: SPL binary without device tree appended |
| ---------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of spl/u-boot-spl-nodtb.bin (default |
| 'spl/u-boot-spl-nodtb.bin') |
| |
| This is the U-Boot SPL binary, It does not include a device tree blob at |
| the end of it so may not be able to work without it, assuming SPL needs |
| a device tree to operation on your platform. You can add a u_boot_spl_dtb |
| entry after this one, or use a u_boot_spl entry instead (which contains |
| both SPL and the device tree). |
| |
| |
| |
| Entry: u-boot-spl-with-ucode-ptr: U-Boot SPL with embedded microcode pointer |
| ---------------------------------------------------------------------------- |
| |
| This is used when SPL must set up the microcode for U-Boot. |
| |
| See Entry_u_boot_ucode for full details of the entries involved in this |
| process. |
| |
| |
| |
| Entry: u-boot-tpl: U-Boot TPL binary |
| ------------------------------------ |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot-tpl.bin (default 'tpl/u-boot-tpl.bin') |
| |
| This is the U-Boot TPL (Tertiary Program Loader) binary. This is a small |
| binary which loads before SPL, typically into on-chip SRAM. It is |
| responsible for locating, loading and jumping to SPL, the next-stage |
| loader. Note that SPL is not relocatable so must be loaded to the correct |
| address in SRAM, or written to run from the correct address if direct |
| flash execution is possible (e.g. on x86 devices). |
| |
| SPL can access binman symbols at runtime. See: |
| |
| 'Access to binman entry offsets at run time (symbols)' |
| |
| in the binman README for more information. |
| |
| The ELF file 'tpl/u-boot-tpl' must also be available for this to work, since |
| binman uses that to look up symbols to write into the TPL binary. |
| |
| |
| |
| Entry: u-boot-tpl-dtb: U-Boot TPL device tree |
| --------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot.dtb (default 'tpl/u-boot-tpl.dtb') |
| |
| This is the TPL device tree, containing configuration information for |
| TPL. TPL needs this to know what devices are present and which drivers |
| to activate. |
| |
| |
| |
| Entry: u-boot-tpl-dtb-with-ucode: U-Boot TPL with embedded microcode pointer |
| ---------------------------------------------------------------------------- |
| |
| This is used when TPL must set up the microcode for U-Boot. |
| |
| See Entry_u_boot_ucode for full details of the entries involved in this |
| process. |
| |
| |
| |
| Entry: u-boot-tpl-with-ucode-ptr: U-Boot TPL with embedded microcode pointer |
| ---------------------------------------------------------------------------- |
| |
| See Entry_u_boot_ucode for full details of the entries involved in this |
| process. |
| |
| |
| |
| Entry: u-boot-ucode: U-Boot microcode block |
| ------------------------------------------- |
| |
| Properties / Entry arguments: |
| None |
| |
| The contents of this entry are filled in automatically by other entries |
| which must also be in the image. |
| |
| U-Boot on x86 needs a single block of microcode. This is collected from |
| the various microcode update nodes in the device tree. It is also unable |
| to read the microcode from the device tree on platforms that use FSP |
| (Firmware Support Package) binaries, because the API requires that the |
| microcode is supplied before there is any SRAM available to use (i.e. |
| the FSP sets up the SRAM / cache-as-RAM but does so in the call that |
| requires the microcode!). To keep things simple, all x86 platforms handle |
| microcode the same way in U-Boot (even non-FSP platforms). This is that |
| a table is placed at _dt_ucode_base_size containing the base address and |
| size of the microcode. This is either passed to the FSP (for FSP |
| platforms), or used to set up the microcode (for non-FSP platforms). |
| This all happens in the build system since it is the only way to get |
| the microcode into a single blob and accessible without SRAM. |
| |
| There are two cases to handle. If there is only one microcode blob in |
| the device tree, then the ucode pointer it set to point to that. This |
| entry (u-boot-ucode) is empty. If there is more than one update, then |
| this entry holds the concatenation of all updates, and the device tree |
| entry (u-boot-dtb-with-ucode) is updated to remove the microcode. This |
| last step ensures that that the microcode appears in one contiguous |
| block in the image and is not unnecessarily duplicated in the device |
| tree. It is referred to as 'collation' here. |
| |
| Entry types that have a part to play in handling microcode: |
| |
| Entry_u_boot_with_ucode_ptr: |
| Contains u-boot-nodtb.bin (i.e. U-Boot without the device tree). |
| It updates it with the address and size of the microcode so that |
| U-Boot can find it early on start-up. |
| Entry_u_boot_dtb_with_ucode: |
| Contains u-boot.dtb. It stores the microcode in a |
| 'self.ucode_data' property, which is then read by this class to |
| obtain the microcode if needed. If collation is performed, it |
| removes the microcode from the device tree. |
| Entry_u_boot_ucode: |
| This class. If collation is enabled it reads the microcode from |
| the Entry_u_boot_dtb_with_ucode entry, and uses it as the |
| contents of this entry. |
| |
| |
| |
| Entry: u-boot-with-ucode-ptr: U-Boot with embedded microcode pointer |
| -------------------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot-nodtb.dtb (default 'u-boot-nodtb.dtb') |
| - optional-ucode: boolean property to make microcode optional. If the |
| u-boot.bin image does not include microcode, no error will |
| be generated. |
| |
| See Entry_u_boot_ucode for full details of the three entries involved in |
| this process. This entry updates U-Boot with the offset and size of the |
| microcode, to allow early x86 boot code to find it without doing anything |
| complicated. Otherwise it is the same as the u_boot entry. |
| |
| |
| |
| Entry: vblock: An entry which contains a Chromium OS verified boot block |
| ------------------------------------------------------------------------ |
| |
| Properties / Entry arguments: |
| - keydir: Directory containing the public keys to use |
| - keyblock: Name of the key file to use (inside keydir) |
| - signprivate: Name of provide key file to use (inside keydir) |
| - version: Version number of the vblock (typically 1) |
| - kernelkey: Name of the kernel key to use (inside keydir) |
| - preamble-flags: Value of the vboot preamble flags (typically 0) |
| |
| Output files: |
| - input.<unique_name> - input file passed to futility |
| - vblock.<unique_name> - output file generated by futility (which is |
| used as the entry contents) |
| |
| Chromium OS signs the read-write firmware and kernel, writing the signature |
| in this block. This allows U-Boot to verify that the next firmware stage |
| and kernel are genuine. |
| |
| |
| |
| Entry: x86-start16: x86 16-bit start-up code for U-Boot |
| ------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of u-boot-x86-16bit.bin (default |
| 'u-boot-x86-16bit.bin') |
| |
| x86 CPUs start up in 16-bit mode, even if they are 32-bit CPUs. This code |
| must be placed at a particular address. This entry holds that code. It is |
| typically placed at offset CONFIG_SYS_X86_START16. The code is responsible |
| for changing to 32-bit mode and jumping to U-Boot's entry point, which |
| requires 32-bit mode (for 32-bit U-Boot). |
| |
| For 64-bit U-Boot, the 'x86_start16_spl' entry type is used instead. |
| |
| |
| |
| Entry: x86-start16-spl: x86 16-bit start-up code for SPL |
| -------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of spl/u-boot-x86-16bit-spl.bin (default |
| 'spl/u-boot-x86-16bit-spl.bin') |
| |
| x86 CPUs start up in 16-bit mode, even if they are 64-bit CPUs. This code |
| must be placed at a particular address. This entry holds that code. It is |
| typically placed at offset CONFIG_SYS_X86_START16. The code is responsible |
| for changing to 32-bit mode and starting SPL, which in turn changes to |
| 64-bit mode and jumps to U-Boot (for 64-bit U-Boot). |
| |
| For 32-bit U-Boot, the 'x86_start16' entry type is used instead. |
| |
| |
| |
| Entry: x86-start16-tpl: x86 16-bit start-up code for TPL |
| -------------------------------------------------------- |
| |
| Properties / Entry arguments: |
| - filename: Filename of tpl/u-boot-x86-16bit-tpl.bin (default |
| 'tpl/u-boot-x86-16bit-tpl.bin') |
| |
| x86 CPUs start up in 16-bit mode, even if they are 64-bit CPUs. This code |
| must be placed at a particular address. This entry holds that code. It is |
| typically placed at offset CONFIG_SYS_X86_START16. The code is responsible |
| for changing to 32-bit mode and starting TPL, which in turn jumps to SPL. |
| |
| If TPL is not being used, the 'x86_start16_spl or 'x86_start16' entry types |
| may be used instead. |
| |
| |
| |
