git: boot: Expose SMBIOS entry point via kenv

[Aaron LI]

commit 5e488df32cb01056a5b714a522e51c69ab7b4612
Author: Aaron LI <aly at aaronly.me>
Date:   Sat May 6 08:48:11 2023 +0800

    boot: Expose SMBIOS entry point via kenv
    
    The SMBIOS Reference Specification (v3.6.0) says (in Section 5.2.1):
    
    "On UEFI-based systems, the SMBIOS Entry Point structure can be located
    by looking in the EFI Configuration Table for the SMBIOS GUID
    (SMBIOS_TABLE_GUID, {EB9D2D31-2D88-11D3-9A16- 0090273FC14D}) and using
    the associated pointer."
    
    So export the SMBIOS entry point via kenv to allow the SMBIOS table be
    found in UEFI-only mode, where the BIOS is not mapped into the standard
    address space and thus the SMBIOS table might not appear between 0xf0000
    and 0xfffff.  For example, dmidecode(8) was failing with:
    
        Scanning /dev/mem for entry point.
        # No SMBIOS nor DMI entry point found, sorry.
    
    Use the same kenv 'hint.smbios.0.mem' as FreeBSD to help with dports(7).
    
    Refer-to: FreeBSD (revision 307326)
    Discussed-with: swildner

Summary of changes:
 stand/boot/pc32/libi386/smbios.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/5e488df32cb01056a5b714a522e51c69ab7b4612


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