Typo: (IIRC ACPI has the same problem [with consistency], but you have the luxury of NOT having to worry about that [in the context of EBBR]). ________________________________ From: Andrei Warkentin <[email protected]> Sent: Monday, May 4, 2020 1:34 PM To: Grant Likely <[email protected]>; [email protected] <[email protected]> Cc: Francois Ozog <[email protected]>; Ard Biesheuvel <[email protected]> Subject: Re: [EBBR PATCH] Add EFI GUID for device tree blob
Hi Grant, Please also factor in requirements for how memory containing DT must be described in the memory map (Ard mentioned using EfiACPIReclaimMemory). Maybe something like: * Devicetree loaded at boot time must be contained in memory of type EfiACPIReclaimMemory. Not a strong position, but you may also want to put the foot down on *when* the exposed Devicetree blob must be consistent (consistent with some firmware setting changes). Perhaps thats at ReadyToBoot or ExitBootServices. I don't think the exact choice matters as long as it's called out, so that an OS loader can be coded to fetch the blob exactly once at the right time, and be guaranteed to work on any EBBR-compliant implementation (IIRC ACPI has the same problem, but you have the luxury of having to worry about that). You might want to expand the GUID text to be something like: The following GUID must be used to describe the flattened Devicetree blob (dtb) in the EFI_CONFIGURATION_TABLE structure referenced by the EFI System Table. A ________________________________ From: Grant Likely <[email protected]> Sent: Monday, May 4, 2020 12:20 PM To: [email protected] <[email protected]> Cc: Grant Likely <[email protected]>; Andrei Warkentin <[email protected]>; Francois Ozog <[email protected]> Subject: [EBBR PATCH] Add EFI GUID for device tree blob None of the relevent specs (EFI, DT, EBBR) specify the GUID for passing a DTB. Add it to the EBBR document so it is documented somewhere relevant. Fixes: #45 Cc: Andrei Warkentin <[email protected]> Cc: Francois Ozog <[email protected]> Signed-off-by: Grant Likely <[email protected]> --- source/chapter2-uefi.rst | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/source/chapter2-uefi.rst b/source/chapter2-uefi.rst index f6a5802..cf2f652 100644 --- a/source/chapter2-uefi.rst +++ b/source/chapter2-uefi.rst @@ -86,6 +86,16 @@ tables. - An Advanced Configuration and Power Interface [ACPI]_ table, or - a Devicetree [DTSPEC]_ system description +A Devicetree system description MUST be provided in Flattened Devicetree (DTB) +format version 17 or higher. +The following GUID must be used in the EFT system table to identify the DTB. + +.. code-block:: c + + #define EFI_DTB_GUID \ + EFI_GUID(0xb1b621d5, 0xf19c, 0x41a5, \ + 0x83, 0x0b, 0xd9, 0x15, 0x2c, 0x69, 0xaa, 0xe0) + As stated above, EBBR systems must not provide both ACPI and Devicetree tables at the same time. Systems that support both interfaces must provide a configuration -- 2.20.1 IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. _______________________________________________ boot-architecture mailing list [email protected] https://lists.linaro.org/mailman/listinfo/boot-architecture
