12th Generation Intel® Core™ Processors Datasheet, Volume 1 of 2
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Intel Volume Management Device Technology
Standard Operating Systems generally recognize individual PCIe Devices and load individual drivers. This is undesirable in some cases such as, for example, when there are several PCIe-based hard-drives connected to a platform where the user wishes to configure them as part of a RAID array. The Operating System current treats individual hard-drives as separate volumes and not part of a single volume.
In other words, the Operating System requires multiple PCIe devices to have multiple driver instances, making volume management across multiple host bus adapters (HBAs) and driver instances difficult.
Intel Volume Management Device (VMD) technology provides a means to provide volume management across separate PCI Express HBAs and SSDs without requiring operating system support or communication between drivers. For example, the OS will see a single RAID volume instead of multiple storage volumes, when Volume Management Device is used.
Intel Volume Management Device technology does this by obscuring each storage controller from the OS, while allowing a single driver to be loaded that would control each storage controller.
Intel Volume Management technology requires support in BIOS and driver, memory and configuration space management.
A Volume Management Device (VMD) exposes a single device to the operating system, which will load a single storage driver. The VMD resides in the processor's PCIe root complex and it appears to the OS as a root bus integrated endpoint. In the processor, the VMD is in a central location to manipulate access to storage devices which may be attached directly to the processor or indirectly through the PCH. Instead of allowing individual storage devices to be detected by the OS and therefore causing the OS to load a separate driver instance for each, VMD provides configuration settings to allow specific devices and root ports on the root bus to be invisible to the OS.
Access to these hidden target devices is provided by the VMD to the single, unified driver.
Supports MMIO mapped Configuration Space (CFGBAR):
Supports MMIO Low
Supports MMIO High
Supports Register Lock or Restricted Access
Supports Device Assign
MSI Remapping Disable