On Sat, Sep 22, 2012 at 01:46:57PM +0000, Blue Swirl wrote: > On Fri, Sep 21, 2012 at 11:17 AM, Vasilis Liaskovitis > <vasilis.liaskovitis@xxxxxxxxxxxxxxxx> wrote: > > Example: > > "-dimm id=dimm0,size=512M,node=0,populated=off" > > There should not be a need to introduce a new top level option, > instead you should just use -device, like > -device dimm,base=0,id=dimm0,size=512M,node=0,populated=off > > That would also specify the start address. What is "base"? the start address? I think the start address should be calculated by the chipset / board, not by the user. The "-dimm" option is supposed to specify the dimm/memory layout, and not create any devices. If we don't want this new option, I have a question: A "-device/device_add" means we create a new qdev device at startup or as a hotplug operation respectively. So, the semantics of "-device dimm,id=dimm0,size=512M,node=0,populated=on" are clear to me. What does "-device dimm,populated=off" mean from a qdev perspective? There are 2 alternatives: - The device is created on the dimmbus, but is not used/populated yet. Than the activation/acpi-hotplug of the dimm may require a separate command (we used to have "dimm_add" in versions < 3). "device_add" handling always hotplugs a new qdev device, so this wouldn't fit this usecase, because the device already exists. In this case, the actual "acpi hotplug" operation is decoupled from qdev device creation. - The dimmdevice is not created when "-device dimm,populated=off" (this would require some ugly checking in normal -device argument handling). Only the dimm layout is saved. The hotplug is triggered from a normal device_add later. So in this case, the "acpi hotplug" happens at the same time as the qdev hotplug. Do you see a simpler alternative without introducing a new option? Using the "-dimm" option follows the second semantic and avoids changing the "-device" semantics. Dimm layout description is decoupled from dimmdevice creation, and qdev hotplug coincides with acpi hotplug. thanks, - Vasilis -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
