[Crash-utility] [PATCH 2/3] crash: ARM: get online CPUs from cpu_active_mask

[Dave Anderson]

----- Original Message -----
> On 2014/4/26 3:20, Dave Anderson wrote:
> > 
> > 
> > ----- Original Message -----
> >> For ARM32 platfrom, The system will "offline" all CPUs except the
> >> crashing one, by clear the cpu_online_mask. So we need to find
> >> another way to get online-CPUs number for crash utility.
> >>
> >> This patch uses cpu_active_mask to get that value.
> >>
> >> Signed-off-by: Liu Hua <sdu.liu at huawei.com>
> >> ---
> >>  arm.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/arm.c b/arm.c
> >> index 3c38cd5..c94d7bf 100644
> >> --- a/arm.c
> >> +++ b/arm.c
> >> @@ -1518,7 +1518,7 @@ arm_display_machine_stats(void)
> >>  static int
> >>  arm_get_smp_cpus(void)
> >>  {
> >> -	return get_cpus_online();
> >> +	return get_cpus_active();
> >>  }
> >>  
> >>  /*
> > 
> > When did this start happening?  I ask because no other ARM users have
> > reported this until now.  I've only got one sample SMP vmcore, and
> > clearly the non-crashing cpu was not offlined:
> > 
> 
> 
> Hi Dave,
> 
>  commit 36a2e5010fe87 "kexec: offline non panic CPUs on Kdump panic "
>  introduces this change. <v3.10.27-1-g36a2e50>
> 
>  The following messges come from the ARM boards on my hand. The crash
>  utility has added my patchs.
> 
> (1) ARM A15 16 CPUs
> 
>   crash> sys
> 
>       KERNEL: vmlinux
>     DUMPFILE: vmcore_my  [PARTIAL DUMP]
>         CPUS: 16
>         DATE: Fri Feb 28 10:07:55 2014
>       UPTIME: 00:03:57
> LOAD AVERAGE: 0.03, 0.01, 0.01
>        TASKS: 140
>     NODENAME: arma15el
>      RELEASE: 3.10.37+
>      VERSION: #2 SMP Thu Apr 24 21:13:28 CST 2014
>      MACHINE: armv7l  (unknown Mhz)
>       MEMORY: 3.1 GB
>        PANIC: "Internal error: Oops: a07 [#1] SMP ARM" (check log for details
> 
>   crash> help -k
>        ....
>        cpu_possible_map: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
>        cpu_present_map: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
>        cpu_online_map: 0
>        ...
> 
> 
> (2) ARM A9 4 CPUs
> 
> crash> sys
>       KERNEL: vmlinux
>     DUMPFILE: vmcore
>         CPUS: 2
>         DATE: Mon Apr 14 11:09:10 2014
>       UPTIME: 00:06:17
> LOAD AVERAGE: 0.16, 0.05, 0.02
>        TASKS: 45
>     NODENAME: arma9el
>      RELEASE: 3.10.37+
>      VERSION: #6 SMP Tue Apr 22 13:23:30 CST 2014
>      MACHINE: armv7l  (unknown Mhz)
>       MEMORY: 1.5 GB
>        PANIC: "Internal error: Oops: 817 [#1] SMP ARM" (check log for
>        details)
> 
>   crash> help -k
>        ....
> 	cpu_possible_map: 0 1
>         cpu_present_map: 0 1
>         cpu_online_map: 1
> 
> 
>    crash> p per_cpu__runqueues
> 
>    PER-CPU DATA TYPE:
>    struct rq runqueues;
>    PER-CPU ADDRESSES:
>    [0]: c069a680
>    [1]: c06a2680
> 
> With my patches, "sys" command is ok. And I can get per_cpu variables correctly.
> But something should be done for "help -k". May be I should add fully support
> for cpu_active_mask. If necessory, I will resend this patch series.

It's not necessary, but it would be nice to have, and would be 
easy to add. 

Also, would it be possible that you can let me have a copy of your
16-cpu vmlinux/vmcore pair?  That would be a great sample for
my testing.  

Thanks,
  Dave