[libvirt-users] Mount URL as cdrom/iso KVM/QEMU

Thu Aug 9 14:36:57 UTC 2018

On Thu, Aug 09, 2018 at 11:46:24AM +0000, Inception Hosting wrote:
> Hi Daniel,
> 
> 
> I have noticed that it will fail exactly as you said if <cdrom> is first in
> the boot order, if <hd> is first in the boot order the XML validates and it starts as usual.

That is interesting....

> 
> first in log except below is with cdrom set to first in boot order, second is with hd set first.
> 
> 2018-08-09 11:39:28.625+0000: starting up libvirt version: 3.9.0, package: 14.el7_5.6 (CentOS BuildSystem <http://bugs.centos.org>, 2018-06-27-14:13:57, x86-01.bsys.centos.org), qemu version: 2.10.0(qemu-kvm-ev-2.10.0-21.el7_5.4.1), hostname: devnode9.com

> -drive file=http://distro.ibiblio.org:80/puppylinux/puppy-xenial/32/xenialpup-7.5-uefi.iso,format=raw,if=none,id=drive-ide0-0-1,readonly=on
> -device ide-cd,bus=ide.0,unit=1,drive=drive-ide0-0-1,id=ide0-0-1,bootindex=2
> -drive file=/dev/Kvmvol/kvm104_img,format=raw,if=none,id=drive-virtio-disk0,cache=none
>< -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1

Here we actually see the HD set first (bootindex=1) and CDROM set secound (bootindex=2)

> 2018-08-09 11:40:04.963+0000: starting up libvirt version: 3.9.0, package: 14.el7_5.6 (CentOS BuildSystem <http://bugs.centos.org>, 2018-06-27-14:13:57, x86-01.bsys.centos.org), qemu version: 2.10.0(qemu-kvm-ev-2.10.0-21.el7_5.4.1), hostname: devnode9.com

> -drive if=none,id=drive-ide0-0-1,readonly=on
> -device ide-cd,bus=ide.0,unit=1,drive=drive-ide0-0-1,id=ide0-0-1,bootindex=2
> -drive file=/dev/Kvmvol/kvm104_img,format=raw,if=none,id=drive-virtio-disk0,cache=none
> -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1

And this is the same boot order.  What's different, however ,is that libvirt has launched
the QEMU with no media present in the CDROM tray, so there's no URL for QEMU to complain
about.

I dont know what would have caused libvirt to drop the URL for this CDROM...

> 
> Cheers.
> 
> ________________________________
> From: Daniel P. Berrangé <berrange at redhat.com>
> Sent: 09 August 2018 12:27
> To: Inception Hosting
> Cc: Vasiliy Tolstov; libvirt-users at redhat.com
> Subject: Re: [libvirt-users] Mount URL as cdrom/iso KVM/QEMU
> 
> On Thu, Aug 09, 2018 at 10:50:46AM +0000, Inception Hosting wrote:
> > Just a quick correction and apologies, the actual issue is that http
> > will not work, https will so I dont think this is a bug as such I
> > think this is by design likely for security.
> >
> >
> > Looking at the man page for qemu-kvm it states http will work with
> > examples given however only https works, my best guess from looking
> > at the spec file from the srpm is that it has only been enabled in
> > the centos qemu-kvm-ev with https:
> 
> Yes, the qemu RPMs in centos & RHEL have disabled support for http://
> protocol, however, I expect that to immediately fail when trying to
> start the guest. eg
> 
> # /usr/libexec/qemu-kvm  -drive file=http://example.com/foo/bar -accel tcg
> qemu-kvm: -drive file=http://example.com/foo/bar: Driver 'http' is not whitelisted
> 
> so I'm puzzelled why your guest successfully started at all with a
> http protocol in use.
> 
> Are you able to share your QEMU log from /var/log/libvirt/qemu/$GUESTNAME.log
> from a VM that fails to launch with http ?
> 
> Regards,
> Daniel
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Regards,
Daniel
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