Re: [Crash-utility] Handle the NT_PRSTATUS lost for the "bt" command
----- Original Message -----
> That seems to be a bug (?), but it's not particularly
important,
> because for x86 and x86_64, the data in the NT_PRSTATUS notes is
> only used if the starting point for backtraces if the PC/SP pair
> cannot be determined otherwise, which is the case virtually all of
> the time. So the registers found in the NT_PRSTATUS notes are
> pretty much useless...
I seem to be minor bug, if some of cpus are offline while panic,
can't backtrace the same number of cpus from tail because of returning NULL.
I think current task's PC/SP can not obtain from thread_struct corectly,
then NT_PRSTATUS notes need to be stored for them instead.
For the active tasks, the PC/SP starting points can typically be found
by looking at the stack contents. The NT_PRSTATUS notes are a relatively
recent addition to compressed kdumps, i.e., have only existed since
header version 4. Only in very rare circumstances do the x86 and
x86_64 arches need to utilize the registers in the compressed kdump
NT_PRSTATUS notes.
That being said, I will fix the invalid value that is stored in
dd->num_prstatus_notes so that diskdump_get_prstatus_percpu()
will work as expected if there are offline cpus. That function is
currently used only by x86 and x86_64, so there should be no issues
with the other arches.
Yes I'm going to rework, and thanks for your reviews.
I'm modifying difficult parts this time, very helpful.
I'll do more tests before sending reworked PPC only patch.
I also have to study about kexectools or makedumpfile more about
how NT_PRSTATUS or others are treated, haven't understood enough.
OK thanks,
Dave