[Qemu-devel] AioContext, IOthread and Block migration thread

[Yaodong Yang]

I'm a newer in QEMU, and I have the following questions:

1. Is it true that all the requests to disk images need to go through function 
bdrv_co_do_readv() or bdrv_co_do_writev()?

2. In block-migration thread, the bdrv_co_do_readv is also called to read 
blocks from disk images, in order to finish migration. How do migration thread 
and IOthread cooperate with each other? there is an coroutine created inside 
migration thread and a new botoom half created for this purpose, but I do not 
understand well about it. Could someone explain it for me?

3. What is the meaning of copy on read ?

Thanks!
Yaodong