mfsbsd booted with Grub stuck on black screen (on HPE ProLiant BL460c Gen10 servers)

[MGlaus]

I'm aware that this use case may be not supported. If this is the case feel free to close the issue.

My Setup

My server provisioning tool uses Grub over PXE Boot to start a mfsbsd installation (also over pxe) to then install FreeBSD on the server. This is done because the provisioning tool customizes the Grub config to pass a script path over a kernel parameter to mfsbsd.

To boot into mfbsd we use the following grub config. The referenced files (/boot/freebsd/12.4/kernel.gz , /boot/freebsd/12.4/device.hints, /boot/freebsd/12.4/mfsroot.gz) are extracted out of a self built mfsbsd image.

menuentry 'FreeBSD (mfsBSD) PXEGrub2 12.4' {
  set root=(http,10.2.0.20)
  kfreebsd /boot/freebsd/12.4/kernel.gz -h -v
  kfreebsd_loadenv /boot/freebsd/12.4/device.hints
  kfreebsd_module /boot/freebsd/12.4/mfsroot.gz type=mfs_root
  set kFreeBSD.hw.memtest.tests=0
  set kFreeBSD.kern.vty=vt
  set kFreeBSD.kern.console=efi,comconsole
  set kFreeBSD.vfs.root.mountfrom=ufs:/dev/md0
  set kFreeBSD.mfsbsd.mac_interfaces=ext1
  set kFreeBSD.mfsbsd.ifconfig_ext1_mac=$net_default_mac
  set kFreeBSD.mfsbsd.ifconfig_ext1=DHCP
  set kFreeBSD.provisioning.url=http://provisioning.domain.tld:8080/unattended/provision
}

The problem

This setup worked for FreeBSD 12.4 and earlier. But with FreeBSD 13.2 or 13.3 , after grub executed, the server hangs on a black screen (before any FreeBSD Output). This issue only occurs on HPE ProLiant BL460c Gen10 dervers, on HPE ProLiant BL460c Gen9 servers mfsbsd boots without a problem.

I did have other problems with the FreeBSD 13.2 bootloader on the Gen10 servers, but these i could resolve by defining some setting sin the bios and loader.conf.
I tried to set the following setting in mfsbsd but it did not work.

comconsole_speed="115200"
boot_multicons="YES"
boot_serial="YES"

I even tried to pass some of these settings over Grub to the kernel with kfreebsd /boot/freebsd/12.4/kernel.gz -D -v -S115200 (and some variations of it), but again it did nothing.

I appreciate any help or hints but understand if this is not the right place to ask this.