SMBIOS entry point

[Mark Kettenis]

> From: Heinrich Schuchardt <xypron.glpk at gmx.de>
> Date: Thu, 15 Oct 2020 19:18:21 +0200
> 
> According to
> 
> DSP0134, 3.4.0, System Management BIOS (SMBIOS) Reference Specification
> https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.4.0.pdf
> 
> our struct smbios_entry is an SMBIOS 2.1 (32-bit) Entry Point structure.
> This structure requires that the SMBIOS table is located below 4 GiB.
> 
> Some boards (ZynqMP, Versal) do not have memory mapped in the low 4 GiB
> of the address space. So shouldn't we use the SMBIOS 3.0 (64-bit) Entry
> Point structure?
> 
> Is there any restriction on 32bit boards that would stop us from using
> the SMBIOS 3.0 Entry Point?

I don't think so.  You'll have to advertise it using the
SMBIOS3_TABLE_GUID though.  And maybe some older OSes don't support it
yet though.  Apparently providing both the 32-bit and 64-bit entry
point is allowed.

Other arm64 UEFI implementations (EDK2 and whatever Lenovo/Ampere
provides on their systems) do provide the SMBIOS 3.0 entry point and
currently that is all that OpenBSD checks for on arm64.