Bug 514831 - cannot attach USB floppy device to existing VM
cannot attach USB floppy device to existing VM
Product: Fedora
Classification: Fedora
Component: libvirt (Show other bugs)
All Linux
low Severity medium
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Assigned To: Daniel Veillard
Fedora Extras Quality Assurance
Depends On:
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Reported: 2009-07-30 19:12 EDT by James Ralston
Modified: 2009-07-31 05:04 EDT (History)
6 users (show)

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Doc Type: Bug Fix
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Last Closed: 2009-07-31 05:04:21 EDT
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Description James Ralston 2009-07-30 19:12:58 EDT
I have a KVM-based virtual guest on my laptop. I've attached a USB floppy drive (which appears as /dev/sdb) to my laptop. I need to make that floppy drive visible to the guest.


virsh # attach-disk myguest /dev/sdb fd0 --driver tap --type floppy
error: No support floppy in command 'attach-disk'

Hmmm. Let's try without --floppy:

virsh # attach-disk myguest /dev/sdb fd0 --driver tap
error: internal error cannot attach device on inactive domain

Ok, so I start the virtual guest, then try again:

virsh # attach-disk myguest /dev/sdb fd0 --driver tap --type floppy
error: this function is not supported by the hypervisor: disk bus 'ide' cannot be hotplugged.


From searching, I see that others have had problems performing this operation as well, but I haven't seen any resolutions.

For now, I've taken a decidedly brute-force approach, which is to rename /usr/bin/qemu-kvm to /usr/bin/qemu-kvm.REAL, and create this script as /usr/bin/qemu-kvm:

#! /bin/sh
exec qemu-kvm.REAL $@ -fda /dev/sdb

It works, but virsh could really use a healthy sprinkle of FAIL-B-GONE...


Comment 1 Daniel Berrange 2009-07-31 05:04:21 EDT
The 'attach-disk' command is for transient hotplugging of new disks, or changing the media on existing CDROM/floppy disks. It cannot hotplug IDE disks/cdroms or floppy disks, only hotplug VirtIO or SCSI.

If you wish to add a floppy disk, then power off the VM, and use 'virsh edit GUEST' to alter the persistent config. Or use a combination fo 'virsh dumpxml', emacs, followed by 'virsh define'.

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