On Tue, 9 Aug 2022 at 13:11, Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> 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@xxxxxxxxx> 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.
