Is it possible to update AMI bios from Linux?

I have a motherboard on Supermicro server (model X9SCM(+)/X9SCM). And it is not possible to update it via Supermicro Update Manager - looks like bmc just cannot communicate with bios at all on this motherboard.

I have read that AMI joined LVFS service in 2018. However, in their account it is said:

Restricted to upload firmware for any hardware with vendor ID: DMI:American Megatrends Inc.

I misunderstand that. They restrict uploads to their hardware? So how it is then possible to update?

Official Statement: AMI enables customers to create BIOS update packages that can be uploaded to LVFS. So users can create update packages themselves?

I have not found any information about how to do it. Maybe there is some unofficial (external) repository with .cub files for fwupdmgr?

I have loaded archlinux live iso, installed fwupd and run fwupdmgr get-devices, but got:

root@archiso ~ # fwupdmgr get-devices 
Unknown                  [***************************************]
WARNING: UEFI capsule updates not available or enabled
  See https://github.com/fwupd/fwupd/wiki/PluginFlag:capsules-unsupported for more information.
X9SCL/X9SCM

At that url they say that bios setting that enabling capsule updates may fix that, but I cannot see such option in bios settings.

Am I missing something? Or it is just AMI completely restricted updates only to its proprietary utility?

In the downloadable update archive file from supermicro web site there is a firmware file and afudos utility. It is Ami Firmware Update utility for DOS. While it is possible to update such way, it is inconvenient.

I have seen several variants of AFU utility for different kinds of operating systems:

• afudos for Disk Operating System
• afuefi for Unified Extensible Firmware Interface Shell
• afuwin for Microsoft Windows
• afulnx for Linux

I have successfully tested updating with afuefi from uefi shell. From hdd it works perfectly fine. I used aptio 4 version of afuefi, because aption 5 version said to do so, looks generation dependent. I have also made an eltorito bootable iso with needed files. But the problem it the ipmi virtual media speed, which is unusably slow and impossible to even begin flashing.

Probably, afulnx version could do the trick, but it is only mentioned in pdf files when you download AFU archives from official page. But there is no afulnx there. Is it possible to find it somewhere? Why it is not in official archives?

Maybe there are some other semi-official ways of upgrading? For example, "UEFI BIOS Updater" (UBU)?

Is it possible to update AMI bios/uefi from Linux?