Reimplementing printk() [LWN.net]

Reimplementing printk()

Posted Feb 27, 2019 8:45 UTC (Wed) by jogness (subscriber, #49775)
In reply to: Reimplementing printk() by Cyberax
Parent article: Reimplementing printk()

You really should be using the sequence number. That is a reliable, monotonically increasing value. (For my proposal as well.) Also, it allows you to identify if messages are missing.

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Reimplementing printk()

Posted Feb 27, 2019 9:45 UTC (Wed) by Cyberax (✭ supporter ✭, #52523) [Link] (3 responses)

I can't read /dev/kmsg, it might not be accessible. dmesg is all I can reliably get :(

Reimplementing printk()

Posted Feb 27, 2019 11:10 UTC (Wed) by jogness (subscriber, #49775) [Link] (2 responses)

Isn't dmesg just using /dev/kmsg? Or are you using "dmesg -S"?

Reimplementing printk()

Posted Feb 28, 2019 20:34 UTC (Thu) by Cyberax (✭ supporter ✭, #52523) [Link] (1 responses)

I get piped dmesg output. I can play with its options but I don't see how I can make it print sequence numbers.

Reimplementing printk()

Posted Mar 6, 2019 10:46 UTC (Wed) by jogness (subscriber, #49775) [Link]

If you can call dmesg, I expect you can read /dev/kmsg as well. Take a look at the output of:

cat /dev/kmsg

The second field is the sequence number. You can read about the format here:

https://www.kernel.org/doc/Documentation/ABI/testing/dev-...