On 02.03.2012, at 17:20, Scott Wood wrote:
> On Fri, Mar 02, 2012 at 03:12:33PM +0100, Alexander Graf wrote:
>> When running inside a virtual machine, we can not modify timebase, so
>> let's just not call the functions for it then.
>>
>> This resolves hangs when booting e500 SMP guests on overcommitted hosts.
>>
>> Reported-by: Stuart Yoder <B08248@xxxxxxxxxxxxx>
>> Signed-off-by: Alexander Graf <agraf@xxxxxxx>
>> ---
>> arch/powerpc/platforms/85xx/smp.c | 7 +++++++
>> 1 files changed, 7 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/85xx/smp.c b/arch/powerpc/platforms/85xx/smp.c
>> index ff42490..d4b6c1f 100644
>> --- a/arch/powerpc/platforms/85xx/smp.c
>> +++ b/arch/powerpc/platforms/85xx/smp.c
>> @@ -249,6 +249,13 @@ void __init mpc85xx_smp_init(void)
>> smp_85xx_ops.cause_ipi = doorbell_cause_ipi;
>> }
>>
>> + /* When running under a hypervisor, we can not modify tb */
>> + np = of_find_node_by_path("/hypervisor");
>> + if (np) {
>> + smp_85xx_ops.give_timebase = NULL;
>> + smp_85xx_ops.take_timebase = NULL;
>> + }
>> +
>> smp_ops = &smp_85xx_ops;
>
> Again, for 85xx we should *never* sync the timebase in the kernel,
> hypervisor or no.
The code says "if the kexec config option is enabled, do the sync". I'm fairly sure it's there for a reason.
Git blame points to the following commit:
commit f933a41e419a954ef90605224e02c3ded78f3372
Author: Matthew McClintock <msm@xxxxxxxxxxxxx>
Date: Wed Jul 21 16:14:53 2010 -0500
powerpc/85xx: kexec for SMP 85xx BookE systems
Adds support for kexec on 85xx machines for the BookE platform.
Including support for SMP machines
Based off work from Maxim Uvarov <muvarov@xxxxxxxxxx>
Signed-off-by: Matthew McClintock <msm@xxxxxxxxxxxxx>
Signed-off-by: Kumar Gala <galak@xxxxxxxxxxxxxxxxxxx>
Alex
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