There is > com0 at isa0 port 0x3f8/8 irq 4: ns16550a, 16 byte fifo in your dmesg.
So, I assume your box reports com port somehow (via ACPI probably) Some boxes may have comport built into chipset but no external cable for it. I have one, I bought cable separately. Another option is to use UART that connects to USB
