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 Intel Processor Microcode Package for Linux

 CPU microcode is a mechanism to correct certain errata in existing systems.
 The normal preferred method to apply microcode updates is using the system
 BIOS, but for a subset of Intel's processors this can be done at runtime
 using the operating system. This package contains those processors that
 support OS loading of microcode updates.

 The target user for this package are OS vendors such as Linux distributions
 for inclusion in their OS releases. Intel recommends getting the microcode
 using the OS vendor update mechanism. Expert users can of course update their
 microcode directly outside the OS vendor mechanism. This method is complex and
 thus could be error prone.

 Microcode is best loaded from the BIOS. Certain microcode must only be applied
 from the BIOS. Such processor microcode updates are never packaged in this
 package since they are not appropriate for OS distribution. An OEM may receive
 microcode packages that might be a superset of what is contained in this
 package.

 OS vendors may choose to also update microcode that kernel can consume for early
 loading. For e.g. Linux can update processor microcode very early in the kernel
 boot sequence. In situations when the BIOS update isn't available, early loading
 is the next best alternative to updating processor microcode. Microcode states
 are reset on a power reset, hence its required to be updated everytime during
 boot process.

 Loading microcode using the initrd method is recommended so that the microcode
 is loaded at the earliest time for best coverage. Systems that cannot tolerate
 downtime may use the late reload method to update a running system without a
 reboot.

 == About Processor Signature, Family, Model, Stepping and Platform ID ==
 Processor signature is a number identifying the model and version of a
 Intel processor. It can be obtained using the CPUID instruction, and can
 also be obtained via the command lscpu or from the content of /proc/cpuinfo.
 It's usually presented as 3 fields: Family, Model and Stepping
 (In the table of updates below, they are shorten as F, MO and S).

 The width of Family/Model/Stepping is 12/8/4bit, but when arranged in the
 32bit processor signature raw data is like 0FFM0FMS, hexadecimal.
 e.g. if a processor signature is 0x000906eb, it means
 Family=0x006, Model=0x9e and Stepping=0xb

 A processor product can be implemented for multiple types of platforms,
 So in MSR(17H), Intel processors have a 3bit Platform ID field,
 that can specify a platform type from at most 8 types.
 A microcode file for a specified processor model can support multiple
 platforms, so the Platform ID of a microcode (shorten as PI in the table)
 is a 8bit mask, each set bit indicates a platform type that it supports.
 One can find the platform ID on Linux using rdmsr from msr-tools.

 == Microcode update instructions ==
 -- intel-ucode/ --
 intel-ucode directory contains binary microcode files named in
 family-model-stepping pattern. The file is supported in most modern Linux
 distributions. It's generally located in the /lib/firmware directory,
 and can be updated through the microcode reload interface.

 To update early loading initrd, consult your distribution on how to package
 microcode files for early loading. Some distros use update-initramfs or dracut.
 As recommended above, please use the OS vendors are recommended method to ensure
 microcode file is updated for early loading before attempting the late-load
 procedure below.

 To update the intel-ucode package to the system, one need:
 1. Ensure the existence of /sys/devices/system/cpu/microcode/reload
 2. Copy intel-ucode directory to /lib/firmware, overwrite the files in
 /lib/firmware/intel-ucode/
 3. Write the reload interface to 1 to reload the microcode files, e.g.
   echo 1 > /sys/devices/system/cpu/microcode/reload

 If you are using the OS vendor method to update microcode, the above steps may
 have been done automatically during the update process.

 -- intel-ucode-with-caveats/ --
 This directory holds microcode that might need special handling.
 BDX-ML microcode is provided in directory, because it need special commits in
 the Linux kernel, otherwise, updating it might result in unexpected system
 behavior.
 OS vendors must ensure that the late loader patches (provided in
 linux-kernel-patches\) are included in the distribution before packaging the
 BDX-ML microcode for late-loading.

 == 20190618 Release ==
 -- Updates upon 20190514 release --
 Processor             Identifier     Version       Products
 Model        Stepping F-MO-S/PI      Old->New
 ---- new platforms ----------------------------------------

 ---- updated platforms ------------------------------------
 SNB-E/EN/EP  C1/M0    6-2d-6/6d 0000061d->0000061f Xeon E3/E5, Core X
 SNB-E/EN/EP  C2/M1    6-2d-7/6d 00000714->00000718 Xeon E3/E5, Core X
	Intel Processor Microcode Package for Linux

	CPU microcode is a mechanism to correct certain errata in existing systems.
	The normal preferred method to apply microcode updates is using the system
	BIOS, but for a subset of Intel's processors this can be done at runtime
	using the operating system. This package contains those processors that
	support OS loading of microcode updates.

	The target user for this package are OS vendors such as Linux distributions
	for inclusion in their OS releases. Intel recommends getting the microcode
	using the OS vendor update mechanism. Expert users can of course update their
	microcode directly outside the OS vendor mechanism. This method is complex and
	thus could be error prone.

	Microcode is best loaded from the BIOS. Certain microcode must only be applied
	from the BIOS. Such processor microcode updates are never packaged in this
	package since they are not appropriate for OS distribution. An OEM may receive
	microcode packages that might be a superset of what is contained in this
	package.

	OS vendors may choose to also update microcode that kernel can consume for early
	loading. For e.g. Linux can update processor microcode very early in the kernel
	boot sequence. In situations when the BIOS update isn't available, early loading
	is the next best alternative to updating processor microcode. Microcode states
	are reset on a power reset, hence its required to be updated everytime during
	boot process.

	Loading microcode using the initrd method is recommended so that the microcode
	is loaded at the earliest time for best coverage. Systems that cannot tolerate
	downtime may use the late reload method to update a running system without a
	reboot.

	== About Processor Signature, Family, Model, Stepping and Platform ID ==
	Processor signature is a number identifying the model and version of a
	Intel processor. It can be obtained using the CPUID instruction, and can
	also be obtained via the command lscpu or from the content of /proc/cpuinfo.
	It's usually presented as 3 fields: Family, Model and Stepping
	(In the table of updates below, they are shorten as F, MO and S).

	The width of Family/Model/Stepping is 12/8/4bit, but when arranged in the
	32bit processor signature raw data is like 0FFM0FMS, hexadecimal.
	e.g. if a processor signature is 0x000906eb, it means
	Family=0x006, Model=0x9e and Stepping=0xb

	A processor product can be implemented for multiple types of platforms,
	So in MSR(17H), Intel processors have a 3bit Platform ID field,
	that can specify a platform type from at most 8 types.
	A microcode file for a specified processor model can support multiple
	platforms, so the Platform ID of a microcode (shorten as PI in the table)
	is a 8bit mask, each set bit indicates a platform type that it supports.
	One can find the platform ID on Linux using rdmsr from msr-tools.

	== Microcode update instructions ==
	-- intel-ucode/ --
	intel-ucode directory contains binary microcode files named in
	family-model-stepping pattern. The file is supported in most modern Linux
	distributions. It's generally located in the /lib/firmware directory,
	and can be updated through the microcode reload interface.

	To update early loading initrd, consult your distribution on how to package
	microcode files for early loading. Some distros use update-initramfs or dracut.
	As recommended above, please use the OS vendors are recommended method to ensure
	microcode file is updated for early loading before attempting the late-load
	procedure below.

	To update the intel-ucode package to the system, one need:
	1. Ensure the existence of /sys/devices/system/cpu/microcode/reload
	2. Copy intel-ucode directory to /lib/firmware, overwrite the files in
	/lib/firmware/intel-ucode/
	3. Write the reload interface to 1 to reload the microcode files, e.g.
	echo 1 > /sys/devices/system/cpu/microcode/reload

	If you are using the OS vendor method to update microcode, the above steps may
	have been done automatically during the update process.

	-- intel-ucode-with-caveats/ --
	This directory holds microcode that might need special handling.
	BDX-ML microcode is provided in directory, because it need special commits in
	the Linux kernel, otherwise, updating it might result in unexpected system
	behavior.
	OS vendors must ensure that the late loader patches (provided in
	linux-kernel-patches\) are included in the distribution before packaging the
	BDX-ML microcode for late-loading.

	== 20190618 Release ==
	-- Updates upon 20190514 release --
	Processor Identifier Version Products
	Model Stepping F-MO-S/PI Old->New
	---- new platforms ----------------------------------------

	---- updated platforms ------------------------------------
	SNB-E/EN/EP C1/M0 6-2d-6/6d 0000061d->0000061f Xeon E3/E5, Core X
	SNB-E/EN/EP C2/M1 6-2d-7/6d 00000714->00000718 Xeon E3/E5, Core X