hi dear all.
im searching for qemu io (storage) stack. i searched a lot but just found some slides which does not present so
much.is there any text explanation or article or blog post which describes precisely qemu io stack?
I would be grateful if you provide something for me.and have some question hope you answer them.
before ask my question its worth noting that i have an excellent background about Linux io stack and read qemu source code for main iothread and know about qemu structure, guest os ,...
I read [hw/block/virtio-blk.c] and started fromvirtio_blk_handle_output function and trace it until reached toio_submit! that great we reached host kernel libaio syscalls.but what made me confuesd, is what and where and when th stuffs fordoing a typical io request from a typical guest os starts?!
now here is my questions:
1- i wanna know codes which doing so.(start an io request untilio_submit get called)
2- can you give me th exact path of an io request from app in guest osthrough qemu until get to real disk?
3- does it possible to determin bellow featers for an io request:a- which guest os sent this io request?b- address which io request points to?c- request type read/write?d- request size?
4- if there is multiple disks in system, where it is define iorequest is corresponds to which disk?thank a lot