PCI probing in the kernel

My question relates to how does the kernel go about its business of
discovering PCI devices (after boot time) . I am loading the e1000(em)
driver by kldloading the `if_em` module. The kernel seems to be calling the
probe routine multiple times. So the log below includes messages coming from
the kernel and also includes my own debug logs.

 

```

Jun 25 11:16:45 FreeBSD12 kernel: em probing

Jun 25 11:16:45 FreeBSD12 syslogd: last message repeated 5 times

Jun 25 11:16:45 FreeBSD12 kernel: em0: +++ Calling em_register

Jun 25 11:16:45 FreeBSD12 kernel: em probing

Jun 25 11:16:45 FreeBSD12 syslogd: last message repeated 5 times

Jun 25 11:16:45 FreeBSD12 kernel: em0: +++ Calling em_register

Jun 25 11:16:45 FreeBSD12 kernel: em probing

Jun 25 11:16:45 FreeBSD12 kernel: em0: +++ Calling em_register

Jun 25 11:16:45 FreeBSD12 kernel: em0: <Intel(R) PRO/1000 Network
Connection> port 0x2000-0x203f mem
0xfd5c0000-0xfd5dffff,0xfdff0000-0xfdffffff irq 19 at device 1.0 on pci2

Jun 25 11:16:45 FreeBSD12 kernel: em attaching

Jun 25 11:16:45 FreeBSD12 kernel: em0: +++ Calling em_register

Jun 25 11:17:34 FreeBSD12 kernel: em0: Using 2048 TX descriptors and 2048 RX
descriptors

Jun 25 11:17:35 FreeBSD12 kernel: em probing

Jun 25 11:17:35 FreeBSD12 syslogd: last message repeated 5 times

Jun 25 11:17:35 FreeBSD12 kernel: em1: +++ Calling em_register

Jun 25 11:17:35 FreeBSD12 kernel: em probing

Jun 25 11:17:36 FreeBSD12 kernel: Base = 5ee7e000, Length = 8000

```

It seems that the `probe->register` sequence seems to be getting repeated
multiple times until the adapter is identified properly and its resources
allocated. Isn't multiple registration a cause of concern? Or may something
is wrong with the way I think. May be I am not getting it right? Could
someone elaborate?