[Crash-utility] Re: seek error when loading /proc/kcore with type: "page_offset_base"

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On 24/08/05 02:30PM, Tao Liu wrote:
> For live debug, I noticed for cachyos, kallsyms will output 0 address
> for kernel symbols even as root:
> 
> [root@cachyos-x8664 ~]# cat /proc/kallsyms |less
> 0000000000000000 A fixed_percpu_data
> 0000000000000000 A __per_cpu_start
> 0000000000000000 A cpu_debug_store
> 0000000000000000 A irq_stack_backing_store
> ...
> [root@cachyos-x8664 ~]# cat /proc/sys/kernel/kptr_restrict
> 2
> 
> This would prevent crash to detect the kaslr info. To avoid this,
> please enable the address presenting by:
> 
> [root@cachyos-x8664 ~]# echo 0 > /proc/sys/kernel/kptr_restrict
> [root@cachyos-x8664 ~]# cat /proc/kallsyms |less
> 0000000000000000 A fixed_percpu_data
> 0000000000000000 A __per_cpu_start
> 0000000000001000 A cpu_debug_store
> 0000000000002000 A irq_stack_backing_store
> ...
> 
> then invoke the crash for live debug will have no problem.

Tao, thanks for surfacing this. I'm curious why the commit that Kazu referenced
also appears to solve the problem. I can get live debug to work when I compile
crash from HEAD without enabling the addresses. Do you know why?

https://github.com/crash-utility/crash/commit/6752571d8d782d07537a258a1ec8919ebd1308ad

> Also so if you are dealing with the newest kernel, both makedumpfile and 
> crash will need to be newest, otherwise some bugs you may encounter.

Will do!

> Thanks,
> Tao Liu
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