EBBR Notes 2025.04.23 - ARM-software/ebbr GitHub Wiki
Heinrich Schuchardt (Canonical)
Jon Humphreys (Texas Instruments)
Vincent Stehlé (Arm)
Pull #141 : All runtime services optional after ExitBootServices()
Pull #142 : Conditionally require SCMI 2.x, x >= 1 recommended
The two pull requests were discussed; some more investigations are needed to progress on the runtime services, and for the SCMI one some more comments are needed for clarity.
Pull #141 : All runtime services optional after ExitBootServices()
Fear that other OSes need SetVirtualAddressMap() & ConvertPointer()
Linux has efi=novamap
Concerns for automotive about runtime services harming realtime and/or safety
Target of EBBR? Allow all OSes to boot?
We are stricter than UEFI 2.11 at this point
Do we pass SCT if we do not have those services?
Do we have enough to boot Windows today? Even with ACPI?
Check if BSD would be happy without SetVirtualAddressMap() & ConvertPointer()
Pine64 A64 could boot BSD; see list
Try on a mac :)
-> investigate a bit more
Pull #142 : Conditionally require SCMI 2.x, x >= 1 recommended
Is it really desired to prevent 3.0?
Add a comment why it cannot be 3.x and must be 2.x
3.x is guaranteed to be incompatible with 2.x, otherwise it should be called 2.y
Discussion between agent and server could start with 2.1, with negotiation to 3.x
Firmware implementing only 3.x would not be able to support old Linux of today, which support only 2.x
We can revisit when 3.0 is out
Given the complexity, capturing a nice requirement is of help to system implementers
-> polish a bit more
Birds of a feather session at Connect
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