Linux messages truncated (log buffer too small)

[paulmenzel]

The log (ring) buffer for the Linux messages is too small to hold all messages from a boot:

# more /etc/issue
DENT OS DENTOS-HEAD, 2023-06-22.21:43-d97c46b

# more /proc/cmdline
console=ttyS0,115200 earlycon=uart8250,mmio32,0xf0512000 onl_platform=arm64-accton-as5114-48x-r0 arm-smmu.disable_bypass=n maxcpus=4 pci=pcie_bus_safe cpuidle.off=1
# dmesg | wc -l
1862
# dmesg | head
[   22.906794] sfp sfp-4: using device tree for GPIO lookup
[   22.906800] of_get_named_gpiod_flags: can't parse 'rate-select0-gpios' property of node '/sfp-4[0]'
[   22.906810] of_get_named_gpiod_flags: can't parse 'rate-select0-gpio' property of node '/sfp-4[0]'
[   22.906818] sfp sfp-4: using lookup tables for GPIO lookup
[   22.906821] sfp sfp-4: No GPIO consumer rate-select0 found
[   22.906826] sfp sfp-4: Host maximum power 2.0W
[   22.907003] lm75 1-004c: supply vs not found, using dummy regulator
[   22.912853] mdio_bus i2c:sfp-5: GPIO lookup for consumer reset
[   22.917611] mdio_bus i2c:sfp-5: using lookup tables for GPIO lookup
[   22.917615] mdio_bus i2c:sfp-5: No GPIO consumer reset found
# dmesg | tail -21
[   58.355974] br0: port 48(swp48) entered disabled state
[3814524.720900] sfp sfp-9: module removed
[3814537.511919] sfp sfp-9: module BROCADE          57-0000075-01    rev A    sn AAF211210000K91  dc 110519
[3814541.663647] sfp sfp-5: module removed
[3814583.815754] sfp sfp-48: module removed
[3814598.133459] sfp sfp-47: module removed
[3814605.382336] sfp sfp-48: module BROCADE          57-0000075-01    rev A    sn AAA212203415662  dc 120516
[3814609.258902] Aldrin2 0000:01:00.0 swp48: Link is Up - 10Gbps/Full - flow control off
[3814609.266815] IPv6: ADDRCONF(NETDEV_CHANGE): swp48: link becomes ready
[3814609.273639] br0: port 48(swp48) entered blocking state
[3814609.282537] br0: port 48(swp48) entered learning state
[3814609.288186] br0: port 48(swp48) entered forwarding state
[3814609.296572] IPv6: ADDRCONF(NETDEV_CHANGE): br0: link becomes ready
[3814620.390846] sfp sfp-10: module Foundry Networks GBIC-SFP+SR-B    rev B4   sn M4093012         dc 151125
[3814620.400672] Aldrin2 0000:01:00.0 swp10: switched to inband/10gbase-r link mode
[3878924.113868] sfp sfp-17: module OPNEXT,INC       TRS5020EN-S301   rev 0000 sn 0852A-81046      dc 08122600
[3878924.123689] Aldrin2 0000:01:00.0 swp17: switched to inband/10gbase-r link mode
[3878928.624898] sfp sfp-18: module Intel Corp       FTLX8571D3BCV-IT rev A    sn ASS1D2Z          dc 141230
[3878928.634759] Aldrin2 0000:01:00.0 swp18: switched to inband/10gbase-r link mode
[5046838.675280] mvpp2 f2000000.ethernet ma1: Link is Down
[5046888.849309] mvpp2 f2000000.ethernet ma1: Link is Up - 1Gbps/Full - flow control off

No idea, if the Linux configuration should be updated, or the Linux CLI parameter log_buf_len be set.

PS:

Also the journal buffer is too small too store all messages from one boot:

# journalctl -o short-monotonic -b -k | head
-- Logs begin at Sun 2023-07-16 12:08:56 CEST, end at Sun 2023-09-17 14:56:51 CEST. --
[    3.242352] ec-as5114-48x-03.molgen.mpg.de kernel: of_get_named_gpiod_flags: can't parse 'wp-gpio' property of node '/ap806/config-space@f0000000/sdhci@6e0000[0]'
[    3.242371] ec-as5114-48x-03.molgen.mpg.de kernel: xenon-sdhci f06e0000.sdhci: using lookup tables for GPIO lookup
[    3.242376] ec-as5114-48x-03.molgen.mpg.de kernel: xenon-sdhci f06e0000.sdhci: No GPIO consumer wp found
[    3.242713] ec-as5114-48x-03.molgen.mpg.de kernel: ledtrig-cpu: registered to indicate activity on CPUs
[    3.250780] ec-as5114-48x-03.molgen.mpg.de kernel: usbcore: registered new interface driver usbhid
[    3.256390] ec-as5114-48x-03.molgen.mpg.de kernel: usbhid: USB HID core driver
[    3.267911] ec-as5114-48x-03.molgen.mpg.de kernel: mmc0: SDHCI controller on f06e0000.sdhci [f06e0000.sdhci] using ADMA 64-bit
[    3.285050] ec-as5114-48x-03.molgen.mpg.de kernel: netem: version 1.3
[    3.288252] ec-as5114-48x-03.molgen.mpg.de kernel: Initializing XFRM netlink socket