On Wed, 2013-07-17 at 19:33 -0400, KOSAKI Motohiro wrote: > On Wed, Jul 17, 2013 at 7:29 PM, Toshi Kani <toshi.kani@xxxxxx> wrote: > > On Wed, 2013-07-17 at 19:22 -0400, KOSAKI Motohiro wrote: > >> On Wed, Jul 17, 2013 at 5:45 PM, Toshi Kani <toshi.kani@xxxxxx> wrote: > >> > CONFIG_ARCH_MEMORY_PROBE enables /sys/devices/system/memory/probe > >> > interface, which allows a given memory address to be hot-added as > >> > follows. (See Documentation/memory-hotplug.txt for more detail.) > >> > > >> > # echo start_address_of_new_memory > /sys/devices/system/memory/probe > >> > > >> > This probe interface is required on powerpc. On x86, however, ACPI > >> > notifies a memory hotplug event to the kernel, which performs its > >> > hotplug operation as the result. Therefore, users should not be > >> > required to use this interface on x86. This probe interface is also > >> > error-prone that the kernel blindly adds a given memory address > >> > without checking if the memory is present on the system; no probing > >> > is done despite of its name. The kernel crashes when a user requests > >> > to online a memory block that is not present on the system. > >> > > >> > This patch disables CONFIG_ARCH_MEMORY_PROBE by default on x86, > >> > and clarifies it in Documentation/memory-hotplug.txt. > >> > >> Why don't you completely remove it? Who should use this strange interface? > > > > According to the comment below, this probe interface is used on powerpc. > > So, we cannot remove it, but to disable it on x86. > > I meant x86. Why can't we completely remove ARCH_MEMORY_PROBE section > from x86 Kconfig? Oh, I see what you meant. I do not expect any need for end-users, but I was not sure if someone working on the memory hotplug development might use it for fake hot-add testing. Yes, if you folks do not see any need, I will remove it from x86 Kconfig. Thanks, -Toshi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>