[Skiboot] [RFC PATCH] opal/xstop: Use nvram param to enable/disable sw checkstop.

[Oliver]

On Fri, Dec 15, 2017 at 4:15 AM, ppaidipe <ppaidipe at linux.vnet.ibm.com> wrote:
> Hi Mahesh
>
> On 2017-12-14 21:06, Mahesh J Salgaonkar wrote:
>>
>> From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
>>
>> Add a mechanism to enable/disable sw checkstop by looking at nvram option
>> opal-sw-xstop=<enable/disable>.
>>
>> For now this patch disables the sw checkstop trigger unless explicitly
>> enabled through nvram option 'opal-sw-xstop=enable'. This will allow an
>> opportunity to get host kernel in panic path or xmon for unrecoverable
>> HMIs or MCE, to be able to debug the issue effectively.
>
>
> It will be good to enable by default, and let's give control to user to
> disable
> the sw-xstop using nvram option. Otherwise all test infrastructures will
> break.

Why does the test infrastructure require SW initiated checkstops?


>
> Thanks
> Pridhiviraj
>
>
>>
>> To enable sw checkstop in opal issue following command:
>>
>> # nvram -p ibm,skiboot --update-config opal-sw-xstop=enable
>>
>> NOTE: This is a workaround patch to disable sw checkstop by default to
>> gain
>> control in host kernel for better checkstop debugging. Once we have most
>> of
>> the checkstop issues stabilized/resolved, revisit this patch to enable sw
>> checkstop by default.
>>
>> Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
>> ---
>>  hw/xscom.c |   13 +++++++++++++
>>  1 file changed, 13 insertions(+)
>>
>> diff --git a/hw/xscom.c b/hw/xscom.c
>> index de5a27e..4d3d88f 100644
>> --- a/hw/xscom.c
>> +++ b/hw/xscom.c
>> @@ -24,6 +24,7 @@
>>  #include <errorlog.h>
>>  #include <opal-api.h>
>>  #include <timebase.h>
>> +#include <nvram.h>
>>
>>  /* Mask of bits to clear in HMER before an access */
>>  #define HMER_CLR_MASK  (~(SPR_HMER_XSCOM_FAIL | \
>> @@ -827,6 +828,18 @@ int64_t xscom_trigger_xstop(void)
>>  {
>>         int rc = OPAL_UNSUPPORTED;
>>
>> +       /*
>> +        * Workaround until we iron out all checkstop issues at present.
>> +        *
>> +        * By deafult do not trigger sw checkstop unless explicitly
>> enabled
>> +        * through nvram option 'opal-sw-xstop=enable'.
>> +        *
>> +        * NOTE: Once all checkstop issues are resolved/stabilized reverse
>> +        * the logic to enable sw checkstop by default.
>> +        */
>> +       if (!nvram_query_eq("opal-sw-xstop", "enable"))
>> +               return rc;
>> +
>>         if (xstop_xscom.addr)
>>                 rc = xscom_writeme(xstop_xscom.addr,
>>                                 PPC_BIT(xstop_xscom.fir_bit));
>>
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>
>
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