Hi all,
I'm trying to enable CorebootPayloadPkg on PC Engines APU2 (AMD Embedded
G series GX-412TC). I passed some asserts related to RTC and memory
reservation for LAPIC/APIC/HPET. Now it looks like I'm starting UEFI Shell:

[Bds]Booting UEFI Shell
[Bds] Expand
MemoryMapped(0xB,0x830000,0xC0FFFF)/FvFile(7C04A583-9E3E-4F1C-AD65-E05268D0B4D1)
->
MemoryMapped(0xB,0x830000,0xC0FFFF)/FvFile(7C04A583-9E3E-4F1C-AD65-E05268D0B4D1)
PROGRESS CODE: V03058000 I0
InstallProtocolInterface: 5B1B31A1-9562-11D2-8E3F-00A0C969723B CF8FBD40
Loading driver at 0x000CF54D000 EntryPoint=0x000CF556CCF Shell.efi
InstallProtocolInterface: BC62157E-3E33-4FEC-9920-2D3B36D750DF CF927818
ProtectUefiImageCommon - 0xCF8FBD40
  - 0x00000000CF54D000 - 0x00000000000F4380
PROGRESS CODE: V03058001 I0
InstallProtocolInterface: 387477C2-69C7-11D2-8E39-00A0C969723B CF8DEBA0
InstallProtocolInterface: 752F3136-4E16-4FDC-A22A-E5F46812F4CA CF8DDF98

What's missing is UEFI Shell output on serial console. APU2 do not have
wired video output. That's why I would like to enable UEFI Shell output
to serial.

I tried to replace DebugLib with
MdePkg/Library/BaseDebugLibSerialPort/BaseDebugLibSerialPort.inf, but
this lead to reboot after loading protocols.

I believe this is well known problem, but cannot find information about
that. Any pointers would be appreciated.

Best Regards,
-- 
Piotr Król
Embedded Systems Consultant
https://3mdeb.com | @3mdeb_com