(2013/07/18 8:51), Toshi Kani wrote:
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.
I do not think the interface is necessary. So I vote to Kosaki's opinion.
Thanks,
Yasuaki Ishimatsu
Thanks,
-Toshi
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