Bug 821665

If you don't specify a model for the SCSI controller, it uses the defalt which is 'lsi'. Unfortunately RHEL builds of KVM have removed support for this model. This (horrible) error message from KVM is actually telling you that 'lsi' is not supported.

If you want to use multiple virtio-scsi controllers, you should explicitly add multiple <controller> elements requesting virtio-scsi explicitly.

(In reply to comment #1)
> If you don't specify a model for the SCSI controller, it uses the defalt which
> is 'lsi'. Unfortunately RHEL builds of KVM have removed support for this model.
> This (horrible) error message from KVM is actually telling you that 'lsi' is
> not supported.
> 
> If you want to use multiple virtio-scsi controllers, you should explicitly add
> multiple <controller> elements requesting virtio-scsi explicitly.

But for lun logical unit, it can accept more than 7 lun for 1 scsi-id like

-device scsi-block,drive=disk0,scsi-id=0,lun=0 \
-device scsi-block,drive=disk1,scsi-id=0,lun=1 \
-device scsi-block,drive=disk2,scsi-id=0,lun=2 \
-device scsi-block,drive=disk3,scsi-id=0,lun=3 \
-device scsi-block,drive=disk4,scsi-id=0,lun=4 \
-device scsi-block,drive=disk5,scsi-id=0,lun=5 \
-device scsi-block,drive=disk6,scsi-id=0,lun=6 \
-device scsi-block,drive=disk7,scsi-id=0,lun=7 \
-device scsi-block,drive=disk8,scsi-id=0,lun=8 \
-device scsi-block,drive=disk9,scsi-id=0,lun=9 \
-device scsi-block,drive=disk10,scsi-id=0,lun=10 \
-device scsi-block,drive=disk11,scsi-id=0,lun=11 \

in qemu-kvm, we can not implement it with libvirt.

Automatic address assignment in libvirt assumes 7 luns per controller, if you want to go beyond that then you should specify the <address type="scsi" ..../> address details explicitly.

I'm reopening so that the qemu error can be improved.

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Couldn't the error message be improved in libvirt instead?  libvirt already reports errors for all other models that are invalid for qemu.

I don't think it can; all libvirt knows is that qemu has exited, right?  If there is a way for libvirt to be deterministic about what went wrong, I'm happy to fix it there, but I don't know of any way.  Also, I don't think this error is any more helpful for anybody starting qemu from the command line than it is for libvirt users.

I asked because I noticed libvirt doing something similar for usbredir:

    if (!qemuCapsGet(qemuCaps, QEMU_CAPS_USB_REDIR)) {
        qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                        _("USB redirection is not supported "
                          "by this version of QEMU"));
        goto error;
    }

Can be fixed in QEMU too, marking as Capacity.

Yeah, so that was my question--does qemu report that lsi isn't supported in a way that we can gather it into the caps?

Yes,

name "lsi53c895a", bus PCI, alias "lsi"

is present in the output of "qemu -device ?" iff the device is supported.

Eric, do we keep info like supported devices in caps?

We have in the past - we already do a 'qemu -device ?' when computing qemu caps, so it wouldn't be too hard to add another cap and use that to improve our error message.

Ok, thanks all.  I like the error message better from libvirt, so I'm moving back to libvirt.

On qemu-kvm-0.15.1, it supports only lsi scsi controller model.
On qemu-kvm-0.12.1.2, it supports only virtio-scsi-pci scsi model
On qemu 1.1.50, it supports both.
So, instead of using the lsilogic model by default, the patch tries
to check which model the current QEMU supports, then choose it, lsi
has the priority.

If a scsi model is given in XML explicitly, we try to check if
the underlying QEMU supports it or not, raise an error on checking
failure.

Patch sent to upstream
https://www.redhat.com/archives/libvir-list/2012-August/msg00414.html

commit 015c603bcd854b0c8d7ebf613e8f2ebe14c254be
Author: Guannan Ren <gren>
Date:   Wed Aug 8 15:06:33 2012 +0800

    qemu: add two qemu caps for lsi and virtio-scsi SCSI controllers
    
    Rename qemuDefaultScsiControllerModel to qemuCheckScsiControllerModel.
    When scsi model is given explicitly in XML(model > 0) checking if the
    underlying QEMU supports it or not first, raise an error on checking
    failure.
    When the model is not given(mode <= 0), return LSI by default, if
    the QEMU doesn't support it, raise an error.

commit 8694c716ae64a62f3452ed732ef3f74b929aabe8
Author: Guannan Ren <gren>
Date:   Wed Aug 8 14:25:24 2012 +0800

    qemu: add capabilities flags related to scsi controller
    
      QEMU_CAPS_SCSI_LSI
        set the flag when "lsi53c895a", bus PCI, alias "lsi" in
        the output of "qemu -device ?"
        -device lsi in qemu command line
    
      QEMU_CAPS_VIRTIO_SCSI_PCI
        set the flag when "name "virtio-scsi-pci", bus PCI" in
        the output of qemu devices query.
        -device virtio-scsi-pci in qemu command line

Verified it using the following versions. The result is expected.So move its status to VERIFIED.

libvirt-0.10.0-0rc1.el6.x86_64
qemu-kvm-0.12.1.2-2.295.el6.x86_64


Steps
1.# cat rhel6.2.xml
<domain type='kvm'>
......
    <controller type='scsi' index='0' model='lsilogic'/>
......
</domain>


2. # virsh define rhel6.2.xml
error: Failed to define domain from rhel6.2.xml
error: unsupported configuration: This QEMU doesn't support lsi scsi controller


3. Change the model to "virtio-scsi"
# cat rhel6.2.xml
<domain type='kvm'>
......
    <controller type='scsi' index='0' model='virtio-scsi'/>
......
</domain>


4.# virsh define rhel6.2.xml
Domain rhel6.2 defined from rhel6.2.xml


5.# virsh start rhel6.2
Domain rhel6.2 started


6.# virsh edit rhel6.2 ,and Change the model to "lsilogic".


7.# Save it
# virsh edit rhel6.2
error: unsupported configuration: This QEMU doesn't support lsi scsi controller
Failed. Try again? [y,n,f,?]:

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHSA-2013-0276.html