[CentOS] CentOS7 sometimes don't detect NIC after reboot

Tue Sep 17 13:55:57 UTC 2019
Miroslav Geisselreiter <mg at intar.cz>

Dne 17.9.2019 v 15:25 Mauricio Tavares napsal(a):
> On Tue, Sep 17, 2019 at 9:11 AM Miroslav Geisselreiter <mg at intar.cz> wrote:
>> Dne 17.9.2019 v 14:02 Mauricio Tavares napsal(a):
>>> On Tue, Sep 17, 2019 at 7:06 AM Miroslav Geisselreiter <mg at intar.cz> wrote:
>>>> I have brand new PC with this components:
>>>> CPU Intel® Pentium G5400, LGA1151
>>>> motherboard ASUS PRIME B360M-C
>>>> 16 GB RAM
>>>> HDD 2x ADATA SSD 256GB XPG GAMMIX S11, PCIe Gen3x4 M.2 2280 (RAID1)
>>>> NIC Intel X550-T1 Ethernet Converged Network Adapter
>>>> I installed CentOS 7 and two NICs were detected:
>>>> eno1 (on motherboard)
>>>> enp1s0 (Intel X550-T1)
>>>> When I restart the machine sometimes enp1s0 is missing. It is not
>>>> detected during boot. It looks like NIC card is not installed / not
>>>> present. After next reboot everything is fine and I do not see any
>>>> problems with NIC card.
>>>> How can I avoid this problem with missing NIC? Can you help me, please?
>>>         Nothing exciting on dmesg? Did you check the pci chain to see if
>>> it is being reported as there?
>> I do not know what you mean "check the pci chain". My knowledge of
>> kernel level is weak, sorry. What else can I do?
>        The "checking the pci chain" argument is that sometimes the card
> is there but is cheerfully ignored. From
>> [    1.720556] ixgbe 0000:01:00.0: irq 138 for MSI/MSI-X
> You know that it is in bus 1 slot 0, so try something like
> lspci -s 01:00.0 -v
> to see if it reports something there. Just in the odd case the pci
> side of your computer knows there is a card there but the kernel can't
> be bothered (flaky driver?). I am probably not using the right
> terminology, and clearly expect someone to set me right, I've had
> network cards that would show in the pci chain but not in dmesg. Other
> thing you want to think about is that I've had cards that only worked
> if were inserted in a specific slot for no reason whatsoever.
Thank you Mauricio and Mark for fast response.
lspci -s 01:00.0 -v
01:00.0 Ethernet controller: Intel Corporation Ethernet Controller 10G 
X550T (rev 01)
         Subsystem: Intel Corporation Ethernet Converged Network Adapter 
         Flags: bus master, fast devsel, latency 0, IRQ 16
         Memory at a0000000 (64-bit, prefetchable) [size=2M]
         Memory at a0200000 (64-bit, prefetchable) [size=16K]
         Expansion ROM at a2300000 [disabled] [size=512K]
         Capabilities: [40] Power Management version 3
         Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+
         Capabilities: [70] MSI-X: Enable+ Count=64 Masked-
         Capabilities: [a0] Express Endpoint, MSI 00
         Capabilities: [100] Advanced Error Reporting
         Capabilities: [140] Device Serial Number 9f-f8-46-ff-ff-28-00-00
         Capabilities: [150] Alternative Routing-ID Interpretation (ARI)
         Capabilities: [160] Single Root I/O Virtualization (SR-IOV)
         Capabilities: [1a0] Transaction Processing Hints
         Capabilities: [1b0] Access Control Services
         Capabilities: [1c0] Latency Tolerance Reporting
         Capabilities: [1d0] #19
         Kernel driver in use: ixgbe
         Kernel modules: ixgbe

I will check again after reboot and as Mark recommend I will reseat the 
card. I will check BIOS too. As this is production machine I cannot do 
that now. I am going to buy another cheaper 1 Gb Intel card for testing 
purposes. I will report my results later.