Re: Make the 32 bit Frame Pointer backtracer fall back totraditional

From: Linus Torvalds
Date: Fri Jan 11 2008 - 14:42:20 EST




On Thu, 10 Jan 2008, Arjan van de Ven wrote:
>
> What do you think of this approach instead of your proposal?

Looks ok to me. I get the feeling that we *should* be able to make the

#ifdef CONFIG_FRAME_POINTER
..

thing be a bit cleaner with this (since you have the non-frame-pointer
thing inside the loop as well), and use one common routine for it all,
with just certain helper functions always retuning a NULL or something for
the non-frame-pointer thing.

In other words, I *think* the non-frame-pointer case should always be
doable as a "series of single-word unverified frames", but if that kind of
cleanup doesn't work, I certainly don't hate your patch either..

(I also wonder if we should limit the number of entries we print out.
Sometimes the stack frame ends up being so deep that we lose the
*important* stuff. I think it might be good idea to have some rule like
"the first 5 entries go to the screen, the rest will be KERN_DEBUG and
only go to the logs by default" - so a "dmesg" would show it all, but if
the machine is hung, the screen won't have been scrolled away from all
the other things by a long backtrace!)

Linus
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