[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH V1 1/2] Xen acpi memory hotplug driver
>>>> 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? 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). >> * 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. > >> * 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? >> >> 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. Thanks Jinsong _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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