boot guest from passed through AHCI on ESXi 6.0 (can that work??)

Discussion in 'VMware, VirtualBox, Citrix' started by ServeTheServer, Dec 29, 2016.

  1. ServeTheServer

    ServeTheServer New Member

    Dec 29, 2016
    Likes Received:

    I want to try out an all-in-one build. Everything works:
    • ESXi 6.0 boots from usb key
    • A second small usb key is configured as datastore. However because I reserved the memory no swap file and other unwanted writes will take place on the datastore. It only has the vmx files. The vmdk's are sortof replaced by the real disks via the passed through AHCI controller.
    • the Intel AHCI (SunrisePoint 8086:a102) controller is passed through to the vm
    • the vmx only has the sata controller (NO vmware lsi controller) for the cd drive (or is the cd drive IDE like back in the days?)
    • the vm is configured to use BIOS (NOT EFI)
    • when the vm is powered up the guest installation starts from the iso.
    • The OS installer sees the SSD's. So the pass through clearly works.
    • After finishing the installation the guest OS won't boot.
    • Booting the SSD directly instead of the ESXi from the usb key does boot the OS. So it's bootable.
    I suspect that because the AHCI controller doesn't have a bios it isn't bootable. But that limitation isn't very obvious.

    I see three solutions:
    1. Get a large and durable usb key and use that as datastore for the boot disk of the guest. Several drawbacks: not as reliable,durable and fast as a ssd connected directly via sata (remember that there's only usb because all sata ports are passed through), a lot of configuration needed to minimize the amount off writes on the root filesystem.
    2. Get a LSI based SAS card and flash it to IT-mode. These cards are bootable so that probably will work. But is rather expensive, consumes a fair amount of power and it costs me an extra PCIe slot
    3. Get some supported PCIe sata card and connect the bootdrives to that card. Should also work but not ideal and it costs me an extra PCIe slot. However because almost any pcie sata card has a marvel chipset and regardless of the chip model seem to suffer of some obscure bug which prevents them being used when vt-d is enabled at the same time. This makes the sata card also not a very attractive option.
    Is there something I'm missing? Is there a setting to boot the guest from the builtin AHCI controller?

    Please note that I didn't name the guest OS because it's largely irrelevant.

    Thank you for your time and interest,


    Added some finding about the marvel sata chips and vt-d.
    Last edited: Dec 29, 2016
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