[Crash-utility] Re: [PATCH 0/3] Display local variables & function parameters from stack frames
Dave Anderson schrieb:
- These days you'd be hard-pressed to find a distribution kernel that is
compiled with CONFIG_FRAME_POINTER. And if it is, the handling can
be folded into the currently-existing backtracer. (In fact, the original
x86 backtrace code does have a separate code path for kernels that
were built without -fomit-frame-pointer.) But by the time x86_64 came
around, -fomit-frame-pointer was pretty much the default, and I don't think
I've ever seen an x86_64 dumpfile with frame-pointers, certainly not
from a distributor. So, yes it's nice you've got something that works
with that configuration, but it's pretty unrealistic.
AFAIK the hand-written x86_64 assembler code doesn't take the frame
pointer into account. So yes, CONFIG_FRAME_POINTER for x86_64 is really
unrealistic. That may have changed after the x86/x86_64 merge since I
got that statement from Andi Kleen before the merge, but anyway.
the starting point. With the huge cumbersome memory sizes of
modern machines,
it's more likely that the ELF vmcore seen by the secondary kdump kernel will
be run through "makedumpfile -c ..." into the compressed kdump format
prior to the dump ever being seen by whoever analyzes it. At Red Hat, the
support organization pretty much makes all customers use "makedumpfile -c
..."
by default. And of course with the compressed kdump format, there is no
register set as your starting point.
That's also the default for SLES 11. (At least if they didn't change it
in the meanwhile.)
Regards,
Bernhard