[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-ppc] [PATCH v2] ppc: spapr-rtas - implement os-term rtas call

From: Nikunj A Dadhania
Subject: Re: [Qemu-ppc] [PATCH v2] ppc: spapr-rtas - implement os-term rtas call
Date: Wed, 25 Jun 2014 10:06:28 +0530
User-agent: Notmuch/0.17+27~gae47d61 (http://notmuchmail.org) Emacs/24.3.1 (x86_64-redhat-linux-gnu)

Nikunj A Dadhania <address@hidden> writes:

> Alexander Graf <address@hidden> writes:
>> On 17.06.14 11:59, Nikunj A Dadhania wrote:
>>> Alexander Graf <address@hidden> writes:
>>>> On 17.06.14 11:30, Nikunj A Dadhania wrote:
>>>>> Alexander Graf <address@hidden> 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 <address@hidden>
> 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 <address@hidden>
>     Signed-off-by: Benjamin Herrenschmidt <address@hidden>

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.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]