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Date: Mon, 15 Jul 2013 11:46:08 +0800
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20130715034608.GE21224@stefanha-thinkpad.redhat.com>
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Subject: Re: [Qemu-devel] Questions about Block subsystem in QEMU.
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To: Yaodong Yang <yyang@cse.unl.edu>
Cc: qemu-devel@nongnu.org, qemu-discuss@nongnu.org

On Mon, Jul 08, 2013 at 11:15:12PM -0500, Yaodong Yang wrote:
> I have a question about the qemu block-subsytem. When a user in guest os
> perform an io operation, how this io request performed in the qemu. Where
> is the start point in qemu code to serve this request.

QEMU emulates a number of different storage controllers, including
virtio-blk, virtio-scsi, IDE, USB Mass Storage Device, SD cards, etc.

See hw/block/ for storage controller emulation code, which the guest
drivers invoke through hardware register accesses.

Stefan