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    SubjectRe: [PATCHv7 00/14] mm, x86/cc: Implement support for unaccepted memory
    On Tue, 9 Aug 2022 at 13:11, Kirill A. Shutemov
    <kirill.shutemov@linux.intel.com> wrote:
    >
    > On Sat, Jul 23, 2022 at 01:14:07PM +0200, Ard Biesheuvel wrote:
    > > On Thu, 21 Jul 2022 at 19:13, Dave Hansen <dave.hansen@intel.com> wrote:
    > > >
    > > > On 7/19/22 17:26, Marc Orr wrote:
    > > > > - Dave's suggestion to "2. Boot some intermediate thing like a
    > > > > bootloader that does acceptance ..." is pretty clever! So if upstream
    > > > > thinks this FW-kernel negotiation is not a good direction, maybe we
    > > > > (Google) can pursue this idea to avoid introducing yet another tag on
    > > > > our images.
    > > >
    > > > I'm obviously speaking only for myself here and not for "upstream" as a
    > > > whole, but I clearly don't like the FW/kernel negotiation thing. It's a
    > > > permanent pain in our necks to solve a very temporary problem.
    > >
    > > EFI is basically our existing embodiment of this fw/kernel negotiation
    > > thing, and iff we need it, I have no objection to using it for this
    > > purpose, i.e., to allow the firmware to infer whether or not it should
    > > accept all available memory on behalf of the OS before exiting boot
    > > services. But if we don't need this, even better.
    >
    > FW/kernel negotiation does not work if there's a boot loader in the middle
    > that does ExitBootServices(). By the time kernel can announce if it
    > supports unaccepted memory there's nobody to announce to.
    >

    Why would you want to support such bootloaders for TDX anyway? TDX
    heavily relies on measured boot abstractions and other things that are
    heavily tied to firmware.

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