CONFIG_MEMORY_HOTREMOVE is unset for Fedora kernels, but CONFIG_MEMORY_HOTPLUG _is_ set. I was just testing memory hotplug with libvirt + qemu and noticed this, I figured I'd request for it to be enabled for virt testing/dev. I looked for an explanation for why it's off in dist-git but all I got was this: commit 2ee9f1482920f6d831eb6d70458bd0988394982b Author: Dave Jones <davej> Date: Fri Jan 13 17:33:51 2012 -0500 Disable memory hotplug on x86-64 Which seems to be in the midst of disabling a bunch of misc kernel stuff.
*********** MASS BUG UPDATE ************** We apologize for the inconvenience. There is a large number of bugs to go through and several of them have gone stale. Due to this, we are doing a mass bug update across all of the Fedora 23 kernel bugs. Fedora 23 has now been rebased to 4.7.4-100.fc23. Please test this kernel update (or newer) and let us know if you issue has been resolved or if it is still present with the newer kernel. If you have moved on to Fedora 24 or 25, and are still experiencing this issue, please change the version to Fedora 24 or 25. If you experience different issues, please open a new bug report for those.
Looks like latest kernels have this: $ cat /boot/config-4.7.4-200.fc24.x86_64 | grep HOTREMOVE CONFIG_MEMORY_HOTREMOVE=y CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE=y