[Qemu-devel] guest cannot boot up successfully using qemu.git in Xen

[Liu, SongtaoX]

I encountered a problem that the guest cannot boot up successfully using 
qemu.git in Xen.
after creating the guest by "xl cr xlexample.hvm", "xl list" shows the guest's 
vcpu has no status, and "xl vnc $dom_id" cannot connect to the guest.

The qemu.git source is from git://git.qemu.org/qemu.git

The qemu compile steps:
./configure --enable-xen --target-list=x86_64-softmmu 
--extra-cflags="-I/xen-unstable.hg/tools/include -I/xen-unstable.hg/tools/libxc 
-I/xen-unstable.hg/tools/xenstore" 
--extra-ldflags="-L/xen-unstable.hg/tools/libxc 
-L/xen-unstable.hg/tools/xenstore"
make
make install

The xlexample.hvm includes the two lines:
device_model_override= '/usr/local/bin/qemu-system-x86_64'
device_model_version= 'qemu-xen'

Using "git bisect", the commit: 0ca5aa4f4c4a8bcc73988dd52a536241d35e5223 
introduced the problem.

commit 0ca5aa4f4c4a8bcc73988dd52a536241d35e5223
Author: Paolo Bonzini <address@hidden>
Date:   Wed Apr 10 15:23:27 2013 +0200

    qemu-char: another io_add_watch_poll fix

    After attaching the source, we have to remove the reference we hold
    to it, because we do not hold anymore a pointer to the source.

    If we do not do this, removing the source will not finalize it and
    will not drop the "real" I/O watch source.

    This showed up when backporting the new flow control patches to older
    versions of QEMU that still used select.  The whole select then failed
    with EBADF (poll instead will reporting POLLNVAL on a single pollfd)
    and QEMU froze.

    Signed-off-by: Paolo Bonzini <address@hidden>
    Message-id: address@hidden
    Signed-off-by: Anthony Liguori <address@hidden>

Regards
Carl(Songtao)