::msgbuf could see more than 8KB of logs
::msgbuf dcmd in MDB can be very useful for debugging the state of a machine leading up to a crash dump. The messages it reads are stored in a STREAMS data queue,
log_recentq, with a high water mark of
LOG_RECENTSIZE -- presently 8KB.
At this stage, the budget for memory here probably extends to at least, say, 64KB. This would provide eight times more kernel log context in a crash dump.
Updated by Joshua M. Clulow about 1 month ago
Might be worth confirming that roughly the expected number of bytes come out, as well as just that it still works; e.g., via, say:
odin # mdb -k Loading modules: [ unix genunix ... ] > ::msgbuf ! wc -c 7947
(NB: this system has been up for months, and has thus generated a bunch of log messages already. You might need to induce some to be generated for testing!)