Nikunj A Dadhania <nik...@linux.vnet.ibm.com> writes:
> Alexander Graf <ag...@suse.de> writes:
>
>> On 17.06.14 11:59, Nikunj A Dadhania wrote:
>>> Alexander Graf <ag...@suse.de> writes:
>>>> On 17.06.14 11:30, Nikunj A Dadhania wrote:
>>>>> Alexander Graf <ag...@suse.de> writes:
>
>>>>>>> + spapr_rtas_register("ibm,os-term", rtas_ibm_os_term);
>>>>>>> + spapr_rtas_register("ibm,extended-os-term", rtas_ibm_ext_os_term);
>>>>>> Why do we need the extended-os-term if we don't do anything with it?
>>>>> Linux kernel checks for both of them because of legacy:
>>>>>
>>>>> arch/powerpc/kernel/rtas.c:
>>>>>
>>>>> void rtas_os_term(char *str)
>>>>> {
>>>>> [...]
>>>>> /*
>>>>> * Firmware with the ibm,extended-os-term property is guaranteed
>>>>> * to always return from an ibm,os-term call. Earlier versions
>>>>> without
>>>>> * this property may terminate the partition which we want to
>>>>> avoid
>>>>> * since it interferes with panic_timeout.
>>>> But we do not return from the RTAS call, so we don't adhere to the
>>>> extended semantics?
>>> But you would return without calling os-term call if
>>> ibm,extended-os-term isnt registered. For that reason I h ave defined
>>> a
>>> stub.
>>
>> I appreciate the hacker mentality, but Linux explicitly checks on
>> ibm,extended-os-term to ensure that the hypervisor does not stop the VM
>> when it calls ibm,os-term. However, the implementation above does stop
>> the VM when the guest calls ibm,os-term.
>
> Seems to be added to do just that:
>
> commit e9bbc8cde0e3c33b42ddbe1b02108cb5c97275eb
> Author: Anton Blanchard <an...@samba.org>
> Date: Thu Feb 18 12:11:51 2010 +0000
>
> powerpc/pseries: Call ibm,os-term if the ibm,extended-os-term is present
>
> We have had issues in the past with ibm,os-term initiating shutdown of a
> partition. This is confusing to the user, especially if panic_timeout is
> non zero.
>
> The temporary fix was to avoid calling ibm,os-term if a panic_timeout was
> set
> and since we set it on every boot we basically never call ibm,os-term.
>
> An extended version of ibm,os-term has since been implemented which gives
> us
> the behaviour we want:
>
> "When the platform supports extended ibm,os-term behavior, the return
> to the
> RTAS will always occur unless there is a kernel assisted dump active as
> initiated by an ibm,configure-kernel-dump call."
>
> This patch checks for the ibm,extended-os-term property and calls
> ibm,os-term
> if it exists.
>
> Signed-off-by: Anton Blanchard <an...@samba.org>
> Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
I was thinking of the following:
1) Return the RTAS unsupported for extended-os-term
2) A comment in the beginning of the function to suggest that this is a
stub need for legacy of PowerVM
Please let me know your thoughts.
Regards,
Nikunj
