Hang when loading the xhci driver

From: Olivier_Cochard-Labbé <olivier_at_freebsd.org>
Date: Thu, 18 Sep 2025 23:57:27 UTC 
Hi,
I am testing an HP Zbook (Strix Halo) and it boots correctly using the
latest 16 kernel, but only when booting from the USB install media.
Once installed and booting from disk, using the exact same kernel (and
loader.conf), it seems to hang at the xHCI driver loading state.

Extract of the dmesg while booting from USB (working):

pcib7: <API PCI-PCI bridge> at device 8.3 on pci0
pcib5: <ACPI PCI bus> on pcib7
xhci1: <XHCI (generic) USB 3.0 controller> mem 0xd43000...
xhci1: 64 bytes context size, 64-bit DMA

And when booting from disk, it displays the pcib5 line, but hangs here.

What kind of debug feature could I enable here (verbose and safe doesn’t
help) ? Setting hw.usb.xhci.debug=1 in the /boot/loader.conf didn’t display
more detail.
Thanks.