Messages in this thread |  | | Date | Mon, 16 Sep 2002 16:53:44 +0200 | From | Jens Axboe <> | Subject | Re: [linux-usb-devel] Re: [BK PATCH] USB changes for 2.5.34 |
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On Mon, Sep 16 2002, David Woodhouse wrote: > > axboe@suse.de said: > > See, even though I'm not fundamentally against using kernel > > debuggers, I think this is very wrong. Where are you now? You are just > > learning about the bio interface and the changes needed to make it > > run. And this is definitely the most wrong point to start using a > > debugger, and can only result in a dac960 that works by trial and > > error. > > Nevertheless, the existence of a case where it's not sensible to use a > debugger does not prove the non-existence of cases where it _is_ sensible > to use a debugger. > > A case that happened to me recently -- tail-call optimisations screwed up > the return value of a function somewhere deep in the routing code. Adding a > printk made the problem go away. Staring at the C code was also of no use -- > the C code was just fine. > > Now, are you seriously suggesting that instead of using GDB to work out WTF > was going on I should have spent three weeks starting at the output of > 'objdump -d vmlinux' ?
I'm not suggesting anything for your case, and I'm not arguing against kernel debuggers. Please re-read what I wrote: using a debugger for what Daniel is attempting right now is stupid. Are you seriously suggesting that you would trust your data to a driver that had been ported to 2.5, not by studying the interface changes but by 'code blow up, gdb inspection' method? I hope not.
I've used a kernel debugger a few times, for the things I tend to do it's not very helpful. Or let me rephrase that into saying that it's not more helpful than simply having the kernel compiled with -g and using gdb on the resulting vmlinux just for backtraces and code inspection. So I'm fine, and so I don't care very much about the typical pro/con integrated debugger debates.
-- Jens Axboe
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