Once Rob accepts the dtschema patch here, it can be used as a normative reference.
https://github.com/devicetree-org/dt-schema/pull/177
On Sun, 2 Nov 2025 at 15:48, Samer El-Haj-Mahmoud Samer.El-Haj-Mahmoud@arm.com wrote:
Thanks, Ard for the proposal.
We will work on submitting as a CR to the DMTF SMBIOS working group. It would be very helpful if there is a normative reference that defines /chosen/smbios3-entrypoint.
Thanks, --Samer
[1] https://github.com/devicetree-org/devicetree-specification/releases/tag/v0.4
-----Original Message----- From: Ard Biesheuvel ardb@kernel.org Sent: Friday, October 31, 2025 8:28 AM To: Samer El-Haj-Mahmoud Samer.El-Haj-Mahmoud@arm.com; Jose Marinho Jose.Marinho@arm.com Cc: Adriana Nicolae adriana@arista.com; Rob Herring robh@kernel.org; Ilias Apalodimas ilias.apalodimas@linaro.org; Boot Architecture Mailman List boot-architecture@lists.linaro.org; linux-efi linux-efi@vger.kernel.org; open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS devicetree@vger.kernel.org; Tom Rini trini@konsulko.com Subject: SMBIOS discovery for DT platforms booting without EFI
L.S.,
Adriana is proposing [0] a method for DT based platforms that boot without EFI to expose the SMBIOS tables via the /chosen DT node.
There appears to be consensus between the stakeholders in the u-boot and linux communities that this is a reasonable thing to do, and it looks like this is going to be adopted soon.
Adriana has kindly agreed to contributing the u-boot side implementation as well, so all the pieces will be there in terms of code.
What is lacking is a contribution to the DMTF spec, which currently only permits the EFI config table method for non-x86 systems. So some wording should be added to paragraph 5.2.2 (SMBIOS 3.9 [1])
It currently reads
On non-UEFI systems, the 64-bit SMBIOS Entry Point structure can be located by application software by searching for the anchor-string on paragraph (16-byte) boundaries within the physical memory address range 000F0000h to 000FFFFFh.
Given that this makes sense only on x86 systems, I suggest we rephrase this along the lines of
On non-UEFI systems, the 64-bit SMBIOS Entry Point structure can be located by application software
- on x86 systems only, by searching for the anchor-string on paragraph
(16-byte) boundaries within the physical memory address range 000F0000h to 000FFFFFh,
- on DT based systems, by obtaining the physical memory address of the
structure from the /chosen/smbios3-entrypoint property in the device tree.
Maybe Rob can suggest a normative reference to be added to section 2?
Thanks, Ard.
[0] https://lore.kernel.org/all/CAERbo5z6BzHqQxXdxPxmxE_eDR7GGGbt3A8kB0 gQiWFBE-28Ug@mail.gmail.com/T/#u [1] https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3. 9.0.pdf
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