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    SubjectRe: Failure to shutdown/reboot with intel_iommu=on
    Hi Lenny,

    On Tue, May 12, 2020 at 04:00:26PM -0400, Lenny Szubowicz wrote:
    > Some Lenovo laptops provide an ACPI DMAR RMRR that identifies the memory
    > range that the kernel should open up for permissable DMA access
    > for this purpose. Unfortunately, the PCI device that performs these
    > DMA operations is hidden from the kernel by the BIOS. Given that the
    > associated PCI device is hidden, the Linux kernel does not act upon
    > the associated DMAR RMRR.

    That sounds aweful. We should add to the VT-d driver that it sets up
    RMRR mappings for request-ids which are not present as a PCI device, to
    fix the Laptops which have it.

    For the others, is the region the TPM talks to via DMA known so that we
    can add a quirk?


    Joerg

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