Date: Fri, 8 Mar 1996 04:10:08 +1100 From: Bruce Evans <bde@zeta.org.au> To: jkh@time.cdrom.com, lehey.pad@sni.de Cc: hackers@FreeBSD.ORG Subject: Re: using ddb to debug a double-panic? Message-ID: <199603071710.EAA32641@godzilla.zeta.org.au>
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>> 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. This consideration has stopped me from working on both ddb and on my own debugger. gdb over ethernet would be even more interesting. >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 Keyboard drivers are easy to debug using ddb over a serial console. (except ddb doesn't support i/o instructions). Serial drivers and anything else that depends on disabling interrupts are not so easy to debug using ddb because ddb doesn't keep interrupts disabled when tracing and doesn't disable interrupts unless they are already disabled. >addition, kgdb requires a second machine, something that's not always >available. Also, kgdb doesn't have all the facilities of (ddb + This is an important point. I have plenty of machines and serial lines but I only use serial a console when I know in advance that I need it to debug. Bruce
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