* Li, Tianyou (tianyou...@intel.com) wrote: > Hi Dave, > > Thanks for your response. Below are my explanations: > > > Can you explain what you mean by 'persistent' - where do you intend to > > store the guests memory? > > There could be a file or memory region that can survive across guest > shutdown/reboot. Seems Artyom has pointed out the right direction and I have > verified by looking into the code throughout the call stack from > pc_memory_init to qemu_ram_alloc_from_file. I plan to write something like > kernel module to verify the persistency characteristics from guest point of > view.
Maybe it's worth checking the stuff in docs/memory-hotplug.txt - that shows how to create a memory region backed by a file (in that case using a hugepagefs - but I think it's general). Note, I don't think there's a way to use that at the moment for main PC memory. > > > Also, remember that you'll need to save/load the device state as well as > > the rest of RAM. > > Device state handling could be done from two different aspects: 1. From host > perspective or, 2. From guest perspective. From host, qemu will always know > the state of guest devices so that we can use qemu command to checkpoint > states, as you point out (very appreciated that, I do not know the command > xen-save-devices-state before). From guest, it can be something like suspend > to RAM or S3 for PC to checkpoint the current state of PC and restore them > when wakeup. Currently I will prefer the #2. > > In summary, I'd like to have the functionality in qemu that can save & > restore PC main memory at shutdown/power-on phase. Thanks. Dave > > Regards, > Tianyou > > > -----Original Message----- > From: Dr. David Alan Gilbert [mailto:dgilb...@redhat.com] > Sent: Wednesday, April 20, 2016 4:36 PM > To: Li, Tianyou <tianyou...@intel.com> > Cc: qemu-devel@nongnu.org > Subject: Re: [Qemu-devel] Persistent Main Memory in QEmu > > * Li, Tianyou (tianyou...@intel.com) wrote: > > Hi, > > > > Currently we are trying to implement below functionalities in QEmu: main > > memory in guest can be logically viewed as persistent and its content can > > be survived through reboot or shutdown/powerup. > > > > I have looked into the QEmu memory management code include memory.c, exec.c > > and other related source, unfortunately I do not have the chance to get > > clue of how to make QEmu main memory persistent. I found that > > pmemsave<http://doc.opensuse.org/documentation/html/openSUSE_114/opensuse-kvm/cha.qemu.monitor.html#id547777> > > could dump physical memory of guest, but I could not find how to restore > > the dump file before VM startup to execution. > > Can you explain what you mean by 'persistent' - where do you intend to store > the guests memory? > Also, remember that you'll need to save/load the device state as well as the > rest of RAM. If you've got a way to preserve RAM then maybe hte > xen-save-devices-state qemu command could be used to store the rest of > devices. > > Dave > > > > > Could anyone provide some hints to me? Thanks in advance! > > > > Regards, > > Tianyou > -- > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
