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SubjectRe: [linux-usb-devel] Re: [BK PATCH] USB changes for 2.5.34
On Sunday 15 September 2002 21:43, Andrew Morton wrote:
> I suspect the example which you give is not a very typical one. Generally
> people use kgdb for poking around looking at kernel state. I almost never
> single-step. I set breakpoints so that I can inspect state within a
> particular context, and for coverage testing ("is this path being executed").

Right, I almost never single-step either. Probably, my favorite technique
is to replace BUG() with asm("int3").

> Also as a replacement for printk/rebuild/reboot.

Yup. I still use a lot of printks, but they are mostly for tracing, not

> Also for inspecting ad-hoc instrumentation: just add `some_global_int++;'
> and then take a look at its value - much quicker than exposing it via /proc.

Yep, I noticed you doing that, very useful, I picked up that technique
from you. Then I made a little all-purpose proc interface for myself
to make it easy to export my stats structures, which is kind of nice too,
because then you can put a patch out with the hooks still in it, making
it easier for others to participate in the analysis.

> It's also very good to have kgdb on hand when you happen to hit a
> really rare bug - I hit a weirdo request queue corruption thing the
> other day, an hour into a `dbench 1024' run. Was able to get a
> decent amount of information. Heaven knows how long it would take
> to make that bug trigger a second time...

Yes, this last one applies equally to kdb, but since I'm not relying
on kdb at the moment, best to leave the lid on that can of flamable

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