Kernel Overview
You can use dmesg
command to troubleshooting kernel errors. The dmesg
command prints messages from the kernel ring buffer.
The following command, for example, presents kernel messages in a human-readable format:
dmesg --human --kernel
To examine kernel messages as you perform actions, such as reproducing a problem, in another terminal, you can run the command with the --follow
option, which waits for new messages and prints them as they occur:
dmesg --human --kernel --follow
The kernel buffer is limited in memory size. As a result, the kernel cyclically overwrites the end of the information in the buffer from which dmesg
pulls information. The systemd journal, however, saves the information from the buffer to a log file so that you can access older information.
To view it, run the following command:
journalctl -k
If required, you can check the modules that are loaded on your Photon OS machine by running the lsmod
command. For example:
lsmod
Module Size Used by
vmw_vsock_vmci_transport 28672 1
vsock 36864 2 vmw_vsock_vmci_transport
coretemp 16384 0
hwmon 16384 1 coretemp
crc32c_intel 24576 0
hid_generic 16384 0
usbhid 28672 0
hid 106496 2 hid_generic,usbhid
xt_conntrack 16384 1
iptable_nat 16384 0
nf_conntrack_ipv4 16384 2
nf_defrag_ipv4 16384 1 nf_conntrack_ipv4
nf_nat_ipv4 16384 1 iptable_nat
nf_nat 24576 1 nf_nat_ipv4
iptable_filter 16384 1
ip_tables 24576 2 iptable_filter,iptable_nat