[snip]>+config XEN_ACPI_HOTPLUG_MEMORY >+ tristate "Xen ACPI memory hotplug" >+ depends on XEN_DOM0 && XEN_STUB && ACPI >+ default n >+ help >+ This is Xen ACPI memory hotplug. >+ >+ Currently Xen only support ACPI memory hot-add. If you want >+ to hot-add memory at runtime (the hot-added memory cannot be >+ removed until machine stop), select Y/M here, otherwise select N.I''m wondering if the memory removal is not implemented because of the same complication QEMU developers are having. To find a way to keep track of the references to to memory to be removed (e.g in DMA block operations). Did you had this issue? Kind Regards, Erlon
Erlon Cruz wrote:> [snip] >> +config XEN_ACPI_HOTPLUG_MEMORY >> + tristate "Xen ACPI memory hotplug" >> + depends on XEN_DOM0 && XEN_STUB && ACPI >> + default n >> + help >> + This is Xen ACPI memory hotplug. >> + >> + Currently Xen only support ACPI memory hot-add. If you want >> + to hot-add memory at runtime (the hot-added memory cannot be >> + removed until machine stop), select Y/M here, otherwise select N. > > I''m wondering if the memory removal is not implemented because of the > same complication QEMU developers are having. To find a way to keep > track of the references to to memory to be removed (e.g in DMA block > operations). Did you had this issue? >Sorry for late reply. Per my understanding, currently to hot-remove memory is more complicated than to hot-add memory, not only bz of complication of QEMU, but hard to reclaim data structure os/vmm already alloc and occupy. Maybe it would become simpler w/ some h/w assist tech next generation. Thanks, Jinsong
On Mon, Mar 11, 2013 at 5:14 AM, Liu, Jinsong <jinsong.liu@intel.com> wrote:> Erlon Cruz wrote: > > [snip] > >> +config XEN_ACPI_HOTPLUG_MEMORY > >> + tristate "Xen ACPI memory hotplug" > >> + depends on XEN_DOM0 && XEN_STUB && ACPI > >> + default n > >> + help > >> + This is Xen ACPI memory hotplug. > >> + > >> + Currently Xen only support ACPI memory hot-add. If you want > >> + to hot-add memory at runtime (the hot-added memory cannot be > >> + removed until machine stop), select Y/M here, otherwise select N. > > > > I''m wondering if the memory removal is not implemented because of the > > same complication QEMU developers are having. To find a way to keep > > track of the references to to memory to be removed (e.g in DMA block > > operations). Did you had this issue? > > > > Sorry for late reply. > >Hi Liu, thanks for replying, no problem. Per my understanding, currently to hot-remove memory is more complicated> than to hot-add memory, not only bz of complication of QEMU, but hard to > reclaim data structure os/vmm already alloc and occupy. Maybe it would > become simpler w/ some h/w assist tech next generation. > >Hmm, it makes sense. I read a few discussions about the issue on QEMU list but didn''t see any clear solution for the problem.> Thanks, > Jinsong_______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel