Date: Thu, 7 Mar 96 11:58:22 MET From: Greg Lehey <lehey.pad@sni.de> To: jkh@time.cdrom.com (Jordan K. Hubbard) Cc: hackers@freebsd.org (Hackers; FreeBSD) Subject: Re: using ddb to debug a double-panic? Message-ID: <199603071101.MAA23706@nixpbe.pdb.sni.de> In-Reply-To: <13468.826196248@time.cdrom.com>; from "Jordan K. Hubbard" at Mar 07, 96 2:57 am
next in thread | previous in thread | raw e-mail | index | archive | help
>> I've been thinking about improving ddb. About 4 years ago, I wrote a >> similar kernel debugger for BSD/386, and was thinking of incorporating >> some of its features into ddb. One of the things it could do was > > I think the real challenge here is to implement gdb-remote. I was at > Cisco a little while back and got asked this - apparently the Cisco > engineers use the gdb-remote features of their routers to debug IOS > over serial lines. > > We could do the same thing with serial console support and a command > in ddb to drop into gdb-remote mode, then you'd just fire up your > gdb on some other box and say "over there! I want to debug that guy!" I think that there's room for both. I wrote my lowbug because I was dissatisfied with BSDI's kgdb, which does essentially what you describe. In particular, it's difficult to debug a keyboard driver with ddb, and it's difficult to debug a serial driver with kgdb. In addition, kgdb requires a second machine, something that's not always available. Also, kgdb doesn't have all the facilities of (ddb + lowbug), like real hardware memory access breakpoints. I tried looking at the gdb code a while back, and it wasn't very encouraging. Greg
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199603071101.MAA23706>