Date: Tue, 23 Apr 96 15:48:33 MDT From: Greg Lehey <lehey.pad@sni.de> To: erich@lodgenet.com (Eric L. Hernes) Cc: lehey.pad@sni.de, hackers@freebsd.org Subject: Re: request for a new "feature" as regards DDB Message-ID: <199604231348.PAA05687@nixpbe.pdb.sni.de> In-Reply-To: <199604231329.IAA18341@jake.lodgenet.com>; from "Eric L. Hernes" at Apr 23, 96 8:29 am
next in thread | previous in thread | raw e-mail | index | archive | help
> > Greg Lehey writes: >> >> Good idea. I'll add it to my list. For those who don't know, I had >> planned to make some major changes to ddb Real Soon Now. > > I can't remember if it was mentioned before, but I'd like to > see the hardware debug registers used for memory/io watchpoints. This is one of my definite plans. At the risk of repeating what I wrote a couple of months ago, I have already written a kernel debugger (lowbug), which has a number of features lacking in ddb (and vice versa). Hardware breakpointing is one of the lowbug features. > I'll probably whip up something rudimentary in the next couple > days, but full blown support in ddb would be nice. What are you planning to do? > BTW has anyone used the watchpoints claimed to be available in ddb? > It looks like it goes through the vm system, does that make sense? > The man page says that watchpoints on user space work best, what > sense does it make to put a kernel watchpoint on a user address? Why not? One of the things I don't like about ddb (and most other kernel debuggers, for that matter) is that they don't take the user environment into account. Maybe the problem is that the watchpoints slow the kernel down too much. In lowbug, you can set a condition for a breakpoint (or watchpoint, which I prefer to call memory access breakpoints) only to happen on behalf of a specific pid. >> On the other subject, changing out of X into character mode: I believe > > SCO uses dbtty(0|1) to switch from vt0 to sio0 on the fly, This would require appropriate support in the tty driver. I don't know if I like that. > they > also note that the serial line is not initialized in any way, so if > you've got a mouse sitting there, it's now you're console. I'd > say this is probably one of the better ways to handle this situation. Putting the console on the mouse is good? My mouse isn't that intelligent :-) But yes, going serial if the VGA is in X mode is probably a good idea. Greg
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199604231348.PAA05687>