On Thu, Jan 15, 2026 at 09:17:57PM -0800, Greg Steuck wrote:
> My new toy has PCI UART but no legacy COM port:
>
> puc0 at pci0 dev 26 function 0 "Intel C3000 UART" rev 0x11: ports: 16 com
> com4 at puc0 port 0 apic 2 int 16: ns16550a, 16 byte fifo
>
> BIOS redirects to "COM0(Pci Bus0,Dev26,Func0)" which becomes com4.
>
> "set tty com0" or "set tty com4" at boot> both hang (expected, I guess,
> no ISA port, PCI not enumerated yet).
>
> probing: pc0 mem[640K 993M 924M 96M 892K 3M 14336M]
> disk: hd0 hd1
> >> OpenBSD/amd64 BOOTX64 3.70
> boot> set tty com4
> switching console to com4
>
> Getty on tty04 works fine in multiuser.
>
> probing: pc0 mem[640K 993M 924M 96M 892K 3M 14336M]
> disk: hd0 hd1
> >> OpenBSD/amd64 BOOTX64 3.70
> boot> boot
> booting hd0a:/bsd: 22534069+4744208+458880+0+1359872
> [1978765+128+1515096+1204887]=0x203d700
> entry point at 0x1001000
>
> OpenBSD/amd64 (xxx) (tty04)
>
> login:
>
> Question: Is there any way to redirect kernel console to com4 after PCI
> is up, or is console device fixed at boot? If it's fixed, I presume
> that's a fundamental limitation?
find the address for the uart io bar with pcidump -v
then at the boot prompt or in /etc/boot.conf
machine comaddr 0x...
