dmesg does not work

Copitano · 02-05-2021, 07:43 AM

I have a RPi 3B+ connected with a 4 port USB HUB with adapter.
Yesterday after restart of the Pi i had trouble finding ttyUSB0 and ttyUSB1 that where connected directly to the Pi.
Connected to Pi:
16GB USBstick (mounted) USBbackup
4 port USB HUB
mbus to serial converter for Kamstrup 602 heatmeter
RFXcomXL
After restart MBus converter and RFXcom where disconnected. I now connected them to the external USB HUB.
dmesg at first could not find ttyUSB's After another restart it did and i could fix the problem. Now when i typ any dmesg command in conmmandline (Putty) nothing shows however mbus and RFX work in domoticz.
How can i fix this dmesg not showing anything?

Emerson · 02-05-2021, 07:51 AM

Just guessing, your SD card may be dying.

Copitano · 02-05-2021, 05:29 PM

I don't think so because I have been using an eMMC module instead of SD since mid-December.

Emerson · 02-05-2021, 05:34 PM

OK, there must be other logs. I have no Pi running right now, so I cannot check where the kernel log goes, but it must be there somewhere.

Copitano · 02-05-2021, 06:05 PM

Okay, I can see what i can find out.

Copitano · 02-05-2021, 06:51 PM

Found a file named kern.log in /var/log.
its a log list and mostly looks like this:

Code:

Feb  4 21:47:54 raspberrypi kernel: [1892287.451360] ieee80211 phy0: brcmf_run_escan: error (-110)
Feb  4 21:47:54 raspberrypi kernel: [1892287.451384] ieee80211 phy0: brcmf_cfg80211_scan: scan error (-110)
Feb  4 21:48:54 raspberrypi kernel: [1892347.451783] ieee80211 phy0: brcmf_run_escan: error (-110)
Feb  4 21:48:54 raspberrypi kernel: [1892347.451809] ieee80211 phy0: brcmf_cfg80211_scan: scan error (-110)
Feb  4 21:49:54 raspberrypi kernel: [1892407.452206] ieee80211 phy0: brcmf_run_escan: error (-110)
Feb  4 21:49:54 raspberrypi kernel: [1892407.452240] ieee80211 phy0: brcmf_cfg80211_scan: scan error (-110)

However i found reboot info at Feb 4 21:51:10. Thats where trouble started.
Wat should i look for in the file?

Emerson · 02-05-2021, 06:59 PM

Any block device or filesystem errors. Maybe running fsck is in order, perhaps there was some filesystem corruption. Just guessing.

Copitano · 02-05-2021, 08:13 PM

I'm going to investigate further tomorrow. Now sleep first.

Copitano · 02-07-2021, 08:40 AM

Sometimes life can be simple if you don't overlook the most obvious solution. Once in a while I swap the eMMC for an SD with an image of the entire system. I did that today. After replacing the eMMC module and restarting it, all USB ports are found again with dmesg | grep -i usb. Solved!