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
xt_conntrack 16384 2
nft_compat 20480 2
nf_tables 204800 39 nft_compat
nfnetlink 20480 2 nft_compat,nf_tables
xt_LOG 16384 0
nf_log_syslog 20480 0
nf_conntrack 114688 1 xt_conntrack
nf_defrag_ipv6 20480 1 nf_conntrack
nf_defrag_ipv4 16384 1 nf_conntrack
af_packet 45056 2
vmwgfx 294912 1
psmouse 110592 0
drm_ttm_helper 16384 1 vmwgfx
ttm 53248 2 vmwgfx,drm_ttm_helper
vfat 24576 1
drm_kms_helper 118784 1 vmwgfx
fat 69632 1 vfat
syscopyarea 16384 1 drm_kms_helper
sysfillrect 16384 1 drm_kms_helper
sysimgblt 16384 1 drm_kms_helper
fb_sys_fops 16384 1 drm_kms_helper
evdev 20480 2
mousedev 20480 0
button 16384 0
sch_fq_codel 20480 2
drm 368640 5 vmwgfx,drm_kms_helper,drm_ttm_helper,ttm
fuse 114688 1
i2c_core 49152 2 drm_kms_helper,drm
dm_mod 131072 0
loop 28672 0
backlight 16384 1 drm
configfs 36864 1
dmi_sysfs 16384 0
hid_generic 16384 0
usbhid 28672 0
hid 114688 2 usbhid,hid_generic
xhci_pci 16384 0
xhci_hcd 167936 1 xhci_pci
uhci_hcd 40960 0
ehci_pci 16384 0
crc32c_intel 24576 2
ehci_hcd 69632 1 ehci_pci
usbcore 217088 6 xhci_hcd,ehci_pci,usbhid,ehci_hcd,xhci_pci,uhci_hcd
sr_mod 24576 0
cdrom 49152 1 sr_mod
usb_common 16384 4 xhci_hcd,usbcore,ehci_hcd,uhci_hcd
rdrand_rng 16384 0
rng_core 20480 1 rdrand_rng
efivarfs 20480 1
ipv6 450560 270
autofs4 36864 2