Thanks,from the path you have list to me,it can be well explained,but according to the source code,in the end of kvm_init,kvm_memory_listener and kvm_io_listener were registered by memory_listener_register(),and in the end of memory_listener_register(),listener_add_address_space() was called for each address_space,so the listener->region_add was executed then.I do not know what mistake I have made,can you explain it to me ?? thank you very much!
2017-04-17 18:26 GMT+08:00 Peter Xu <pet...@redhat.com>: > On Mon, Apr 17, 2017 at 06:09:11PM +0800, jack.chen wrote: >> hello,I have some questions about memory allocation in qemu for >> virtual machine.I found when configure_accelerator function was called >> ,memory slots were registered to KVM,but at that time address_space >> have not been initialized and ram have not been allocated,it is really >> confused me,Thanks a lot!! > > Here's how I understand it... > > configure_accelerator() does not register memory slots in KVM. > Instead, it registers memory listeners. See > kvm_memory_listener_register(), especially: > > kml->listener.region_add = kvm_region_add; > > That's the hook function to be called when there are new memory region > added to the system. > > Further, when RAM is initialzed, it'll modify the address space layout > of system_memory, and the registered listener of KVM (kvm_region_add) > will be invoked, it'll further sync with kvm. It should be in the > following path if you break at kvm_region_add in gdb: > > #0 0x00005555557ba13a in kvm_region_add (listener=0x5555568330c0, > section=0x7fffffffd310) at /root/git/qemu/kvm-all.c:859 > #1 0x00005555557c1910 in address_space_update_topology_pass > (as=0x55555629e240 <address_space_memory>, old_view=0x5555567a7090, > new_view=0x5555568d3460, adding=true) at /root/git/qemu/memory.c:871 > #2 0x00005555557c19f3 in address_space_update_topology (as=0x55555629e240 > <address_space_memory>) at /root/git/qemu/memory.c:886 > #3 0x00005555557c1b41 in memory_region_transaction_commit () at > /root/git/qemu/memory.c:922 > #4 0x00005555557c4bfd in memory_region_update_container_subregions > (subregion=0x5555568d2fc0) at /root/git/qemu/memory.c:2075 > #5 0x00005555557c4c64 in memory_region_add_subregion_common > (mr=0x5555567a5830, offset=0, subregion=0x5555568d2fc0) at > /root/git/qemu/memory.c:2085 > #6 0x00005555557c4ca0 in memory_region_add_subregion (mr=0x5555567a5830, > offset=0, subregion=0x5555568d2fc0) at /root/git/qemu/memory.c:2093 > #7 0x000055555583fd68 in pc_memory_init (pcms=0x5555567a4100, > system_memory=0x5555567a5830, rom_memory=0x5555568d21a0, > ram_memory=0x7fffffffd550) at /root/git/qemu/hw/i386/pc.c:1383 > #8 0x0000555555847363 in pc_q35_init (machine=0x5555567a4100) at > /root/git/qemu/hw/i386/pc_q35.c:147 > #9 0x0000555555847cac in pc_init_v2_9 (machine=0x5555567a4100) at > /root/git/qemu/hw/i386/pc_q35.c:310 > #10 0x00005555558f7cf8 in main (argc=11, argv=0x7fffffffda78, > envp=0x7fffffffdad8) at /root/git/qemu/vl.c:4557 > > Hope this helps. Thanks. > > -- > Peter Xu
