RE: unable to get virtual serial console for EFI

From: Souradeep Chakrabarti <>
Date: Tue, 24 May 2022 12:29:05 UTC

I am trying to get the virtual serial console to access via putty while booting FreeBSD 13 arm64 bootonly on Hyper-V.

Setting console="efi" is not helping to have the virtual serial console access using putty for ARM64. It is before any kernel module loaded.

I can get the loader output in vmconnect.exe but not in the putty.

Though I can see VM is getting connected to Hyper-V virtual COM1 console. But no output is coming to putty.

I have following question :

Any specific support from EFI firmware, is required for virtual serial to work in EFI loader in this phase of loading?

I can see FreeBSD EFI loader is able to read the ConInDev and ConOutDev variables.

With set console="efi" or set console="comconsole,efi"  or set console="efi" , nothing in getting redirected in putty in arm64.

But in X86 that is not the problem.

Without this debugging the bring up of FreeBSD on arm64 Hyper-V is quite difficult. Any help or pointers are really appreciated.