On Sat, Feb 08, 2020 at 03:27:55PM -0500, Bryan Steele wrote: > On Sat, Feb 08, 2020 at 11:28:41AM +0100, whistlez...@riseup.net wrote: > > Hi, > > I have some strange output from dmesg, what could be ? > > At the follwoing link I've posted some screenshots: > > https://postimg.cc/gallery/1o4wsaw74/ > > Thank you > > I thought this was pretty well known, but you're looking at garbage > from previous boots. Something scribbled over that memory. > > "On some systems the message buffer can survive reboot and be retained > (in the hope of exposing information from a crash)." > > https://man.openbsd.org/dmesg > > -Bryan.
The dmesg buffer is a circular buffer, where old data is at the start and new data is appeneded to it untill it is full, then it wraps around to the start. There are some "magic number" sanity checks, but those are not entirely foolpoof. It's all done as a best effort attempt to preverve logging from across a reboot. -Bryan.
