[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH V1 1/2] Xen acpi memory hotplug driver
Liu, Jinsong wrote: > Konrad Rzeszutek Wilk wrote: >> On Thu, Dec 06, 2012 at 04:27:36AM +0000, Liu, Jinsong wrote: >>>>>>> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index >>>>>>> 126d8ce..abd0396 100644 --- a/drivers/xen/Kconfig >>>>>>> +++ b/drivers/xen/Kconfig >>>>>>> @@ -206,4 +206,15 @@ config XEN_MCE_LOG >>>>>>> Allow kernel fetching MCE error from Xen platform and >>>>>>> converting it into Linux mcelog format for mcelog tools >>>>>>> >>>>>>> +config XEN_ACPI_MEMORY_HOTPLUG >>>>>>> + bool "Xen ACPI memory hotplug" >>>>>> >>>>>> There should be a way to make this a module. >>>>> >>>>> I have some concerns to make it a module: >>>>> 1. xen and native memhotplug driver both work as module, while we >>>>> need early load xen driver. >>>>> 2. if possible, a xen stub driver may solve load sequence issue, >>>>> but it may involve other issues * if xen driver load then >>>>> unload, native driver may have chance to load successfully; >>>> >>>> The stub driver would still "occupy" the ACPI bus for the memory >>>> hotplug PnP, so I think this would not be a problem. >>>> >>> >>> I'm not quite clear your mean here, do you mean it has >>> 1. xen_stub driver + xen_memhoplug driver, then xen_strub driver >>> unload and entirely replaced by xen_memhotplug driver, or >>> 2. xen_stub driver (w/ stub ops) + xen_memhotplug ops (not driver), >>> then xen_stub driver keep occupying but its stub ops later replaced >>> by xen_memhotplug ops? >> >> #2 >>> >>> If in way #1, it has risk that native driver may load (if xen >>> driver unload). If in way #2, xen_memhotplug ops lose the chance to >>> probe/add/bind existed memory devices (since it's done when driver >>> registerred). >> >> Could the stub driver have a queue of events? > > If so, why not do 'real' add ops (like our patch did, to build-in xen > memory hotplug logic)? > I'm not quite clear your purpose of insisting module -- what's > advantage of module you prefer? > >> >>> >>>>> * if xen driver load --> unload --> load again, then it will >>>>> lose hotplug notification during unload period; >>>> >>>> Sure. But I think we can do it with this driver? After all the >>>> function of it is to just tell the firmware to turn on/off sockets >>>> - and if we miss one notification we won't take advantage of the >>>> power savings - but we can do that later on. >>>> >>> >>> Not only inform firmware. >>> Hotplug notify callback will invoke acpi_bus_add -> ... -> >>> implicitly invoke drv->ops.add method to add the hotadded memory >>> device. >> >> Gotcha. > > ? So it will lose the notification and no way to add the new memory > device in the future. > > Xen memory hotplug logic consist of 2 parts: > 1) driver logic (.add/.remove etc) > 2) notification install/callback logic > If you want to use 'xen_stub driver + .add/.remove ops', then > notification install/callback logic would implement with xen_stub > driver (means in build-in part, otherwise it would lose notification > when the ops unload) --> but that would make xen_stub in big build-in > size. How about * build-in part: xen_stub driver (stub .add to record what matched cpu devices) + notification install/callback; * module part: .add/.remove ops; w/ it, native driver has no chance to load and no hotplug event lose, and approximately 1/3 code is build-in and 2/3 are module. I think it will work but I'm not quite sure, at least we can have a try/test? Thanks, Jinsong > >>> >>>> >>>>> * if xen driver load --> unload --> load again, then it will >>>>> re-add all memory devices, but the handle for 'booting memory >>>>> device' and 'hotplug memory device' are different while we have no >>>>> way to distinguish these 2 kind of devices. >>>> >>>> Wouldn't the stub driver hold onto that? >>>> >>> >>> Same question as comment #1. Do you mean it has a xen_stub driver >>> (w/ stub ops) and a xen_memhotplug ops? >> >> Correct. >>> >>>>> >>>>> IMHO I think to make xen hotplug logic as module may involves >>>>> unexpected result. Is there any obvious advantages of doing so? >>>>> after all we have provided config choice to user. Thoughts? >>>> >>>> Yes, it becomes a module - which is what we want. >>>> >>> >>> What I meant here is, module will bring some unexpected issues for >>> xen hotplug. We can provide user 'bool' config choice, let them >>> decide to build-in or not, but not 'tristate' choice. >> >> What would be involved in making it an tristate choice? >>> >>> Thanks >>> Jinsong > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxx > http://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |