devsk wrote: >> James Carlson wrote: >>> - change "console=graphics" to "console=text -k" >> and press enter >> >> ... and you'll probably want "-m >> milestone=single-user" as well. As I >> said, it's not easy to work with. > > I am wondering how do I reproduce this live. May be dumping and doing offline > is best. > > Here is what I am thinking (and hoping, mostly hoping...:-)). I will boot > normally in text console. On the console, I will start 'screen' as root. In > one 'screen' session, I will keep 'ps' typed and in the other I will start > the debugger. I will press enter on 'ps' and jump to 2nd screen session to > get the diagnostic information. Will this work? Will it let me 'C-a 2'? I > have a strong feeling it will not work (similar to your "blind typing" case).
Now an academic question, as Jonathan Adams has likely nailed the underlying problem, but, no, that's not going to work. The world comes to a screeching halt when kmdb wrests control from the kernel. No "screen" or other user-level artifice will help you. Now, if kmdb "knew" how to handle the (sadly) per-adapter graphics/text switching mechanism, or if there were some sort of virtual console mechanism that worked with kmdb, you'd have more luck. But that doesn't exist. For what it's worth, folks inside Sun just attach serial ports to the system and set up "console=ttya" when doing this sort of work. It's the most reliable way to run the kernel under a live debugger. Personally, unless I'm debugging a problem that occurs very, very early in the boot sequence (before the root file system is mounted), I don't bother with this hassle. I stick with post-mortem debugging, because it's far easier. You have the whole UNIX environment to support you when running mdb on a dump. For example, you can do "::dcmds ! grep something" when looking at a dump, but there's no feasible way to do anything like that when you're staring at the kmdb prompt. (A useful trick here, if a driver or daemon is causing the trouble, is to boot up to the point where it dumps, then, on reboot, catch the reboot and use "-m milestone=none". You can then manually mount the file systems you want, use "dumpadm" to set the dump device, and then "savecore".) -- James Carlson 42.703N 71.076W <carls...@workingcode.com> _______________________________________________ observability-discuss mailing list observability-discuss@opensolaris.org
