[Qemu-devel] qemu io path

[Ata Fatahi baarzi <afbcesh91@gmail.com>]

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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 io
thread and know about qemu structure, guest os ,...
i read [hw/block/virtio-blk.c]  and started from
virtio_blk_handle_output function and trace it until reached to
io_submit! that great we reached host kernel libaio syscalls.
but what made me confuesd, is what and where and when th stuffs for
doing 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 until
io_submit get called)
2- can you give me th exact path of an io request from app in guest os
through 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?
e- if there is multiple disks in system, where it is define io
request is corresponds to which disk?
thank a lot



-- 
Best Regrads
Ata Fatahi Baarzi <http://ce.sharif.edu/~fatahibarzi>

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