Re: [Xen-devel] Xen/arm: Virtual ITS command queue handling

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 15/05/15 13:47, Vijay Kilari wrote:
>> Aside ignoring the second bullet it's not possible to drop like that a
>> SYNC/INVALL command sent be the guest. How can you decide when a SYNC is
>> required or not? Why dropping "optional" SYNC would be fine? The spec
>> only says "This command specifies that all actions for the specified
>> re-distributor must be completed"...
> 
>  If Xen is sending SYNC/INVALL commands to pITS based on the commands
> Xen is sending on pITS, there is no harm in ignoring guest commands.
> 
> SYNC/INVALL are always depends on previous ITS commands.
> IMO, Alone these commands does not have any significance.

The SYNC command ensure that any commands before it has been completed...

The guest can decide to put one after only one command or after a batch
of command.

You have to respect it and not let Xen guess when it's necessary to have
one.

Regards,

-- 
Julien Grall

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