Intel VMD in a laptop?

mikeymikec

Lifer
May 19, 2011
15,669
5,878
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I've been getting ready to do a clean install on an Asus TUF Gaming F17 laptop when I was a bit surprised to find that Win11 setup couldn't find any storage devices. I tracked down the issue to Intel VMD being enabled in the BIOS. Intel VMD appears to be an enterprise-level tech to allow hot-plugging SSDs, but why on earth would virtually anyone want that in a laptop, let alone as the default setting?

I can't find any other advantages of Intel VMD, so I've disabled it.
 
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George Nasir

Junior Member
Sep 20, 2022
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Without Intel VMD, the BIOS and operating system of a system handle these events with varied degrees of success. NVMe drives may be added to and removed from the PCIe bus without causing any issues thanks to Intel VMD, which enhances uptime and serviceability.
 

Billy Tallis

Senior member
Aug 4, 2015
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but why on earth would virtually anyone want that in a laptop, let alone as the default setting?
Prior to Tiger Lake (IIRC), Intel implemented NVMe RAID and SSD caching (Optane Memory) using a weird feature of the PCH to hide NVMe drives from the regular PCIe system and make them only accessible through the SATA controller, so that only Intel's RST drivers would be able to find the NVMe drives. OEMs were encouraged to have this functionality enabled by default, and it was sure to be on by default for any model where Optane Memory was one of the available storage options.

When Intel started providing PCIe lanes for NVMe drives direct from the CPU rather than through the PCH, they needed a different method to ensure that regular NVMe driver software couldn't find and claim the drives before Intel RST did. That's why they brought VMD to the consumer CPUs (no, there weren't any plans to start offering hot-swappable NVMe drives in laptops). It had the nice side effect of meaning that Intel's storage hacks for the sake of RST no longer caused problems for Linux users, because VMD was already well-documented and fully supported by Linux, quite the opposite to Intel's prior PCH-based strategy.

Now that Optane Memory is dead, Intel sold their SSD business, and DirectStorage is forcing everyone to stick with the regular Microsoft NVMe drivers, these shenanigans should be gone for good.
 

sdifox

No Lifer
Sep 30, 2005
89,865
11,979
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Without Intel VMD, the BIOS and operating system of a system handle these events with varied degrees of success. NVMe drives may be added to and removed from the PCIe bus without causing any issues thanks to Intel VMD, which enhances uptime and serviceability.
Err nvme is not built for hot swap.
 

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