Re: [Qemu-devel] qemu memory manage question

[jack.chen]

Hello, now I am confused about some structures in qemu related to
memory management,they are
MemoryRegion、AddressSpace、FlatView、FlatRange、MemoryRegionSection、RAMList、RAMBlock、KVMSlot、kvm_userspace_memory_region,who
can tell me the concrete connection among these structures.
thanks a lot!

2017-04-18 10:25 GMT+08:00 jack.chen <address@hidden>:
> Thanks very much!!
>
> 2017-04-17 19:19 GMT+08:00 李强 <address@hidden>:
>>
>>
>>> -----Original Message-----
>>> From: Qemu-devel
>>> [mailto:address@hidden On Behalf Of
>>> jack.chen
>>> Sent: Monday, April 17, 2017 6:56 PM
>>> To: Peter Xu
>>> Cc: qemu
>>> Subject: Re: [Qemu-devel] qemu memory manage question
>>>
>>> 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!
>>>
>>
>> They are callbacks.
>> Every change of memory topology will call these listeners, add 
>> subregion(Peter's example),
>> modify the property of memory, create address space for example.
>>
>> Thanks.
>>
>> --
>> Li Qiang /the Gear Team, Qihoo 360 Inc
>>
>>
>>> 2017-04-17 18:26 GMT+08:00 Peter Xu <address@hidden>:
>>> > 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
>>