(2013/07/20 2:47), Toshi Kani 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, regular users do not need > this interface on x86. This probe interface is also error-prone and > misleading 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 interface is > currently used for testing as it can fake a hotplug event. > > This patch disables CONFIG_ARCH_MEMORY_PROBE by default on x86, adds > its Kconfig menu entry on x86, and clarifies its use in Documentation/ > memory-hotplug.txt. > > Signed-off-by: Toshi Kani <toshi.kani@xxxxxx> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> Thanks, Yasuaki Ishimatsu > --- > Documentation/memory-hotplug.txt | 16 +++++++++------- > arch/x86/Kconfig | 7 ++++++- > 2 files changed, 15 insertions(+), 8 deletions(-) > > diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt > index 8e5eacb..8fd254c 100644 > --- a/Documentation/memory-hotplug.txt > +++ b/Documentation/memory-hotplug.txt > @@ -210,13 +210,15 @@ If memory device is found, memory hotplug code will be called. > > 4.2 Notify memory hot-add event by hand > ------------ > -In some environments, especially virtualized environment, firmware will not > -notify memory hotplug event to the kernel. For such environment, "probe" > -interface is supported. This interface depends on CONFIG_ARCH_MEMORY_PROBE. > - > -Now, CONFIG_ARCH_MEMORY_PROBE is supported only by powerpc but it does not > -contain highly architecture codes. Please add config if you need "probe" > -interface. > +On powerpc, the firmware does not notify a memory hotplug event to the kernel. > +Therefore, "probe" interface is supported to notify the event to the kernel. > +This interface depends on CONFIG_ARCH_MEMORY_PROBE. > + > +CONFIG_ARCH_MEMORY_PROBE is supported on powerpc only. On x86, this config > +option is disabled by default since ACPI notifies a memory hotplug event to > +the kernel, which performs its hotplug operation as the result. Please > +enable this option if you need the "probe" interface for testing purposes > +on x86. > > Probe interface is located at > /sys/devices/system/memory/probe > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index b32ebf9..408ef68 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1344,8 +1344,13 @@ config ARCH_SELECT_MEMORY_MODEL > depends on ARCH_SPARSEMEM_ENABLE > > config ARCH_MEMORY_PROBE > - def_bool y > + bool "Enable sysfs memory/probe interface" > + default n > depends on X86_64 && MEMORY_HOTPLUG > + help > + This option enables a sysfs memory/probe interface for testing. > + See Documentation/memory-hotplug.txt for more information. > + If you are unsure how to answer this question, answer N. > > config ARCH_PROC_KCORE_TEXT > def_bool y > -- 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>