[RFC] [PATCH] cpu_hotplug on IBM JS20 system

[Srinivasa Ds]

Hi
when I tried to hot plug a cpu on IBM bladecentre JS20 system,it dropped 
in to xmon. On analyzing the problem,I found out that "self-stop" token  
is not exported
to the OS through rtas(Could be verified by looking in to 
/proc/device-tree/rtas file).

1:mon> e
cpu 0x1: Vector: 700 (Program Check) at [c00000000ff1bab0]
  pc: c00000000001b144: .rtas_stop_self+0x34/0x70
  lr: c0000000000439c0: .pSeries_mach_cpu_die+0x34/0x40
  sp: c00000000ff1bd30
 msr: 8000000000021032
current = 0xc00000000ff050b0
paca    = 0xc0000000005ec500
  pid   = 0, comm = swapper
kernel BUG in rtas_stop_self at arch/powerpc/kernel/rtas.c:829!
===========================================
void rtas_stop_self(void)
{
      struct rtas_args *rtas_args = &rtas_stop_self_args;

      local_irq_disable();

      BUG_ON(rtas_args->token == RTAS_UNKNOWN_SERVICE);
===================================================
#ifdef CONFIG_HOTPLUG_CPU
      rtas_stop_self_args.token = rtas_token("stop-self");
#endif /* CONFIG_HOTPLUG_CPU */
#ifdef CONFIG_RTAS_ERROR_LOGGING
      rtas_last_error_token = rtas_token("rtas-last-error");
===================================================

Since we are not supported by hardware for cpu hotplug. I have developed 
the patch which will disable cpu hotplug on IBM bladecentre JS20.  
Please let me know your comments on this please.

Signed-off-by: Srinivasa DS <srinivasa at in.ibm.com>





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