On Wednesday 21 December 2016 08:56 AM, Xunlei Pang wrote:
On 12/20/2016 at 11:38 PM, Pratyush Anand wrote:
On Monday 19 December 2016 08:10 AM, Dave Young wrote:
Hi, Pingfan
On 12/19/16 at 10:08am, Pingfan Liu wrote:
kexec-tools always allocates program headers for present cpus. But
when crashing, offline cpus have dummy headers. We do not copy these
dummy notes into ELF file, also have no need of warning on them.
I still think it is not worth such a fix, if you feel a lot of warnings
in case large cpu numbers, I think you can change the pr_warn to
pr_warn_once, we do not care the null cpu notes if it has nothing bad
to the vmcore.
I agree. Warning is more like information here. May be, we can count the number of times
real_sz was 0, and then can print an info at the end in stead of warning, like..."N
number of CPUs would have been offline, PT_NOTE entries was absent for them."
Well, OTOH the warning may also be due to some user-space misuse, we can't
distinguish that without extra information added.
Yes, yes..I agree, I meant that the above info is just indicative. May
be "might have been" could be better word than "would have been" in the
above info print message.
Another possible user-space fix would be: Firstly fix kexec-tools to add notes
only for online cpus,
then utilize udev rules(cpu online/offline events) to automatically trigger
kdump kernel reload.
Hummm..this is certainly possible. But can we do much even when we get
the info that the PT_NOTE was compromised by user space?
Therefore, I am of the view that if at all we are concerned about number
of warning messages in case of multiple offline cpu, then we can just
print the total number of NULL PT_NOTE at the end of loop.
~Pratyush
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