Older Post Home. Subscribe to: Post Comments Atom. Unexplained crashes, microcode updates, and CPU errata Computers are complicated machines. A Common Missight in Most Hypervisors. This isn't exactly related to hypervisor development, I just thought it was a neat find. The English United States version of this software update installs files that have the attributes that are listed in the following tables. Protect yourself online: Windows Security support. Learn how we guard against cyber threats: Microsoft Security.
Learn about the terminology that Microsoft uses to describe software updates. Windows Server, version , all editions Windows 10, version , all editions Windows Server, version , all editions Windows 10, version , all editions More Need more help? Expand your skills. Get new features first. A subscription to help make the most of your time. For up to 6 people.
Premium apps. Try 1 month free. Was this information helpful? Yes No. Thank you! Any more feedback? The more you tell us the more we can help. Can you help us improve? Exceptions to this will generally be communicated. The microcode update is generally cleared by a warm reset.
However, any state that persists across a warm reset for example, last branch records or machine check banks and has been modified by the update will remain modified after the reset. One exception is that certain microcode update components only take effect after a warm reset and thus are not cleared by warm reset. For such components, loading the update stages certain changes to take effect on the next warm reset.
Since a warm reset generally clears the microcode update content, the processor may be affected only by those components that take effect after a warm reset between when that reset occurs and when the microcode update is later reloaded at one of the previously discussed locations for microcode updates. A second warm reset after the update is reloaded is not needed. Some microcode update components may only be effective if the update is loaded at or before a specific load point.
In particular, some components may not take effect if the update is loaded after the late BIOS microcode update, or outside of the FIT. Any such requirements will be documented.
If any component is not effective, it does not prevent other components within the same update from being effective. Some microcode update components may impact system performance.
Since the microcode update load point may determine the effectiveness of certain components, the performance impact of those components may also depend on the load point. Therefore, the same microcode update may have a different performance impact depending on when it is loaded. Loading an update on one logical processor also loads the same update on all other logical processors in the same core all of the sibling hyperthreads.
For some processors, loading an update on one logical processor may also load the same update on logical processors on other physical cores. This may differ based on different configurations. If software attempts to load an update with the same update revision as what is currently loaded, the CPU may or may not reload the update.
Once loaded, some updates may prevent loading of another update with a lower update revision. If loading an update with a lower revision is allowed, loading the lower revision may not clear all aspects of the previously loaded update with the higher revision. Loading a microcode update that creates a new software-controllable state will initialize that state to a well-defined setting described in the documentation associated with that particular capability.
Loading a microcode update will not perturb any settings of previously configured software-controllable states for example, MSR values , even if those states were created by a previously loaded microcode update. To load an update during runtime, software should synchronize all logical processors within the system perform a rendezvous to load the update in a coordinated manner. Once all logical processors have been synchronized, one logical processor in each core should load the update while sibling logical processors wait in a spin loop of only basic instructions.
Some guidelines are:. Note that you can only update to a higher version of microcode. Performance varies by use, configuration and other factors.
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