src/cpu/intel/microcode/Kconfig

config MICROCODE_UPDATE_PRE_RAM
	bool
	depends on SUPPORT_CPU_UCODE_IN_CBFS
	default n if CPU_INTEL_FIRMWARE_INTERFACE_TABLE
	default y
	help
	  Select this option if you want to update the microcode
	  during the cache as RAM setup.

config RELOAD_MICROCODE_PATCH
	bool
	default n
	help
	  Select this option if SoC recommends to re-load microcode
	  patch as part of CPU multiprocessor initialization process.
	  This feature is mostly required with Intel latest generation
	  processors starting with Alder Lake (with modified MCHECK init
	  flow).

config CPU_INTEL_MICROCODE_CBFS_SPLIT_BINS
	bool "For Intel CPU, include microcode per CPUID into CBFS"
	depends on CBFS_VERIFICATION && !MICROCODE_UPDATE_PRE_RAM
	default n
	help
	  This option controls whether to include external microcode binaries per
	  CPUID in CBFS.

	  The current approach of loading microcode blobs post CPU reset is to search
	  the unified blob in the CBFS and then perform the CBFS verification. The bigger
	  the unified microcode blob in size the longer it takes to perform the verification.

	  Select this option to store the split microcode blobs per CPUID in the CBFS.
	  As the microcode blobs will be divided into smaller chunks per CPUID, which will
	  reduce the overall search, verify and load time.

	  The microcode file may be removed from the ROM image at a later
	  time with cbfstool, if desired.

	  If unsure, and applicable, select "Generate from tree"

config CPU_INTEL_UCODE_SPLIT_BINARIES
	string "Specify the split microcode blob directory path"
	depends on CPU_INTEL_MICROCODE_CBFS_SPLIT_BINS
	default ""
	help
	  Provide the split microcode blob directory path if
	  CPU_INTEL_MICROCODE_CBFS_SPLIT_BINS config is enabled.

	  CPU_INTEL_MICROCODE_CBFS_SPLIT_BINS config is allowed to pack the individual microcode
	  patch file per CPUID inside the CBFS.

	  Intel distributes CPU microcode updates based on CPUID as part of the github repository
	  in INC format and expects it also getting used in binary form.

	  For example: Intel CPU microcode `m506e3.inc` is getting converted into F-MO-S
	  (06-5e-03) binary file for Linux kernel.

	  `MicrocodeConverter` is an Intel-provided tool for converting binary form MCU into
	  several other common formats for integration.

	  Implementation logic behind CPU_INTEL_MICROCODE_CBFS_SPLIT_BINS config relies on
	  converting Intel CPU microcode INC file into the binary file as per format specified
	  here `cpu_microcode_$(CPUID).bin`. For example: Intel CPU microcode `m506e3.inc` to
	  convert into `cpu_microcode_506e3.bin` binary file for coreboot to integrate if
	  CPU_INTEL_MICROCODE_CBFS_SPLIT_BINS config is enabled.

	  This config provides the directory name (including path) that holds the split microcode
	  binary files per CPUID as mentioned above for each coreboot variants. For example: if
	  google/kunimitsu had built with Intel SkyLake processor with CPUID `506e3` and `506e4`
	  then CPU_INTEL_UCODE_SPLIT_BINARIES refers to the directory path that holds the split
	  microcode binary files aka `cpu_microcode_506e3.bin` and `cpu_microcode_506e4.bin`.

	  CONFIG_CPU_UCODE_SPLIT_BINARIES="3rdparty/blobs/mainboard/google/kunimitsu/microcode_inputs/kunimitsu"
	  Refer to the file representation below:
	  |---3rdparty
	  |   |--- blobs
	  |   |    |--- mainboard
	  |   |    |   |--- google
	  |   |    |   |    |--- kunimitsu
	  |   |    |   |    |    |--- microcode_inputs
	  |   |    |   |    |    |    |--- kunimitsu
	  |   |    |   |    |    |    |    |--- cpu_microcode_506e3.bin
	  |   |    |   |    |    |    |    |--- cpu_microcode_506e4.bin

	  Users of this config option requires to manually place the microcode binary files per
	  CPUIDs as per the given format (`cpu_microcode_$(CPUID).bin`) in a directory.
	  Finally specify the microcode binary directory path using CPU_UCODE_SPLIT_BINARIES
	  config.

	  At runtime (either from romstage/ramstage), coreboot read the CPUID and search for the
	  `cpu_microcode_$(CPUID).bin` file (in this example: cpu_microcode_506e3.bin) inside RW
	  CBFS. Eventually able to locate the appropriate `cpu_microcode_$(CPUID).bin` file and
	  perform the verification prior loading into the CPUs (BSP and APs).

	  If unsure, leave this blank.