* Peng Tao (tao.p...@linux.alibaba.com) wrote: > By removing the share ram check, qemu is able to migrate > to private destination ram when x-ignore-shared capability > is on. Then we can create multiple destination VMs based > on the same source VM. > > This changes the x-ignore-shared migration capability to > work similar to Lai's original bypass-shared-memory > work(https://lists.gnu.org/archive/html/qemu-devel/2018-04/msg00003.html) > which enables kata containers (https://katacontainers.io) > to implement the VM templating feature. > > An example usage in kata containers(https://katacontainers.io): > 1. Start the source VM: > qemu-system-x86 -m 2G \ > -object > memory-backend-file,id=mem0,size=2G,share=on,mem-path=/tmpfs/template-memory \ > -numa node,memdev=mem0 > 2. Stop the template VM, set migration x-ignore-shared capability, > migrate "exec:cat>/tmpfs/state", quit it > 3. Start target VM: > qemu-system-x86 -m 2G \ > -object > memory-backend-file,id=mem0,size=2G,share=off,mem-path=/tmpfs/template-memory > \ > -numa node,memdev=mem0 \ > -incoming defer > 4. connect to target VM qmp, set migration x-ignore-shared capability, > migrate_incoming "exec:cat /tmpfs/state" > 5. create more target VMs repeating 3 and 4 > > Cc: Dr. David Alan Gilbert <dgilb...@redhat.com> > Cc: Yury Kotov <yury-ko...@yandex-team.ru> > Cc: Jiangshan Lai <la...@hyper.sh> > Cc: Xu Wang <x...@hyper.sh> > Signed-off-by: Peng Tao <tao.p...@linux.alibaba.com>
I think this is OK, but please post this to qemu-devel. Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com> > --- > migration/ram.c | 7 ------- > 1 file changed, 7 deletions(-) > > diff --git a/migration/ram.c b/migration/ram.c > index 1ca9ba7..cdb82a3 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -3373,7 +3373,6 @@ static int ram_save_setup(QEMUFile *f, void *opaque) > } > if (migrate_ignore_shared()) { > qemu_put_be64(f, block->mr->addr); > - qemu_put_byte(f, ramblock_is_ignored(block) ? 1 : 0); > } > } > > @@ -4340,12 +4339,6 @@ static int ram_load(QEMUFile *f, void *opaque, int > version_id) > } > if (migrate_ignore_shared()) { > hwaddr addr = qemu_get_be64(f); > - bool ignored = qemu_get_byte(f); > - if (ignored != ramblock_is_ignored(block)) { > - error_report("RAM block %s should %s be > migrated", > - id, ignored ? "" : "not"); > - ret = -EINVAL; > - } > if (ramblock_is_ignored(block) && > block->mr->addr != addr) { > error_report("Mismatched GPAs for block %s " > -- > 1.8.3.1 > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK