[Xen-users] Hotplug failure when running DomU from ramdisk

[Grant McWilliams <grantmasterflash@xxxxxxxxx>]

I got this brilliant idea to try to run a DomU from ramdisk. Since I'm just calling the disk image from a hard drive it seemed like if I put it in a ramdisk it would boot much faster. However, the boot fails and worse yet after it fails no other DomU will start. The Ramdisk DomU and the other non-modified DomUs die with a hotplug problem. Here's the relevant lines of the xend.log. 

> [2009-12-16 00:12:49 4273] DEBUG (XendDomainInfo:92) XendDomainInfo.create(['vm', ['name', 'student038'], ['memory', '300'], ['on_reboot', 'restart'], ['on_crash', 'restart'], ['vcpus', 1], ['on_xend_start', 'ignore'], ['on_xend_stop', 'shutdown'], ['bootloader', '/usr/bin/pygrub'], ['bootloader_args', ''], ['image', ['linux', ['videoram', 4]]], ['s3_integrity', 1], ['device', ['tap', ['uname', 'tap:aio:/media/ramdisk/student038.img'], ['dev', 'xvda'], ['mode', 'w']]], ['device', ['tap', ['uname', 'tap:aio:/srv/xen/student038-sdb.img'], ['dev', 'sdb'], ['mode', 'w']]], ['device', ['vif', ['bridge', 'classnet0'], ['mac', '00:16:3e:00:00:38']]]])
>
> [2009-12-16 00:12:49 4273] DEBUG (XendDomainInfo:2296) XendDomainInfo.constructDomain
> [2009-12-16 00:12:49 4273] DEBUG (balloon:166) Balloon: 315164 KiB free; need 4096; done.
> [2009-12-16 00:12:49 4273] DEBUG (XendDomain:452) Adding Domain: 21
>
> [2009-12-16 00:12:49 4273] DEBUG (XendDomainInfo:2497) XendDomainInfo.initDomain: 21 256
> [2009-12-16 00:12:49 12655] DEBUG (XendBootloader:113) Launching bootloader as ['/usr/bin/pygrub', '--output=/var/run/xend/boot/xenbl.12024', '/media/ramdisk/student038.img'].
>
> [2009-12-16 00:12:54 4273] DEBUG (XendDomainInfo:2521) _initDomain:shadow_memory=0x0, memory_static_max=0x12c00000, memory_static_min=0x0.
> [2009-12-16 00:12:54 4273] DEBUG (balloon:166) Balloon: 315052 KiB free; need 309248; done.
>
> [2009-12-16 00:12:54 4273] INFO (image:173) buildDomain os=linux dom=21 vcpus=1
> [2009-12-16 00:12:54 4273] DEBUG (image:659) domid          = 21
> [2009-12-16 00:12:54 4273] DEBUG (image:660) memsize        = 300
> [2009-12-16 00:12:54 4273] DEBUG (image:661) image          = /var/run/xend/boot/boot_kernel.lDjkNL
> [2009-12-16 00:12:54 4273] DEBUG (image:662) store_evtchn   = 1
> [2009-12-16 00:12:54 4273] DEBUG (image:663) console_evtchn = 2
> [2009-12-16 00:12:54 4273] DEBUG (image:664) cmdline        = ro root=/dev/VolGroup00/LogVol00 console=xvc0 
>
> [2009-12-16 00:12:54 4273] DEBUG (image:665) ramdisk        = /var/run/xend/boot/boot_ramdisk.baaFxA
> [2009-12-16 00:12:54 4273] DEBUG (image:666) vcpus          = 1
> [2009-12-16 00:12:54 4273] DEBUG (image:667) features       = 
>
> [2009-12-16 00:12:54 4273] DEBUG (image:668) flags          = 0
> [2009-12-16 00:12:54 4273] INFO (XendDomainInfo:2160) createDevice: tap : {'bootable': 1, 'uname': 'tap:aio:/media/ramdisk/student038.img', 'mode': 'w', 'dev': 'xvda', 'uuid': '3580acaf-6e6b-2111-0327-d983ed9a7775'}
>
> [2009-12-16 00:12:54 4273] DEBUG (DevController:95) DevController: writing {'virtual-device': '51712', 'device-type': 'disk', 'protocol': 'x86_64-abi', 'backend-id': '0', 'state': '1', 'backend': '/local/domain/0/backend/tap/21/51712'} to /local/domain/21/device/vbd/51712.
>
> [2009-12-16 00:12:54 4273] DEBUG (DevController:97) DevController: writing {'domain': 'student038', 'frontend': '/local/domain/21/device/vbd/51712', 'uuid': '3580acaf-6e6b-2111-0327-d983ed9a7775', 'bootable': '1', 'dev': 'xvda', 'state': '1', 'params': 'aio:/media/ramdisk/student038.img', 'mode': 'w', 'online': '1', 'frontend-id': '21', 'type': 'tap'} to /local/domain/0/backend/tap/21/51712.
>
> [2009-12-16 00:12:54 4273] INFO (XendDomainInfo:2160) createDevice: tap : {'bootable': 0, 'uname': 'tap:aio:/srv/xen/student038-sdb.img', 'mode': 'w', 'dev': 'sdb', 'uuid': '3b6979ff-50c9-ef28-2544-6320970fb2c2'}
>
> [2009-12-16 00:12:54 4273] DEBUG (DevController:95) DevController: writing {'virtual-device': '2064', 'device-type': 'disk', 'protocol': 'x86_64-abi', 'backend-id': '0', 'state': '1', 'backend': '/local/domain/0/backend/tap/21/2064'} to /local/domain/21/device/vbd/2064.
>
> [2009-12-16 00:12:54 4273] DEBUG (DevController:97) DevController: writing {'domain': 'student038', 'frontend': '/local/domain/21/device/vbd/2064', 'uuid': '3b6979ff-50c9-ef28-2544-6320970fb2c2', 'bootable': '0', 'dev': 'sdb', 'state': '1', 'params': 'aio:/srv/xen/student038-sdb.img', 'mode': 'w', 'online': '1', 'frontend-id': '21', 'type': 'tap'} to /local/domain/0/backend/tap/21/2064.
>
> [2009-12-16 00:12:55 4273] INFO (XendDomainInfo:2160) createDevice: vif : {'bridge': 'classnet0', 'mac': '00:16:3e:00:00:38', 'uuid': '56b5c2ad-9490-e6f3-7267-a3ae848b5ce4'}
>
> [2009-12-16 00:12:55 4273] DEBUG (DevController:95) DevController: writing {'mac': '00:16:3e:00:00:38', 'handle': '0', 'protocol': 'x86_64-abi', 'backend-id': '0', 'state': '1', 'backend': '/local/domain/0/backend/vif/21/0'} to /local/domain/21/device/vif/0.
>
> [2009-12-16 00:12:55 4273] DEBUG (DevController:97) DevController: writing {'bridge': 'classnet0', 'domain': 'student038', 'handle': '0', 'uuid': '56b5c2ad-9490-e6f3-7267-a3ae848b5ce4', 'script': '/etc/xen/scripts/vif-bridge', 'mac': '00:16:3e:00:00:38', 'frontend-id': '21', 'state': '1', 'online': '1', 'frontend': '/local/domain/21/device/vif/0'} to /local/domain/0/backend/vif/21/0.
>
> [2009-12-16 00:12:55 4273] DEBUG (XendDomainInfo:3052) Storing VM details: {'on_xend_stop': 'shutdown', 'shadow_memory': '0', 'uuid': 'd297fda1-d5fe-e7a6-4925-f7aa8a706bd3', 'on_reboot': 'restart', 'start_time': '1260951175.05', 'on_poweroff': 'destroy', 'bootloader_args': '', 'on_xend_start': 'ignore', 'on_crash': 'restart', 'xend/restart_count': '0', 'vcpus': '1', 'vcpu_avail': '1', 'bootloader': '/usr/bin/pygrub', 'image': "(linux (kernel ) (videoram 4) (notes (FEATURES 'writable_page_tables|writable_descriptor_tables|auto_translated_physmap|pae_pgdir_above_4gb|supervisor_mode_kernel') (VIRT_BASE 18446744071562067968) (GUEST_VERSION 2.6) (PADDR_OFFSET 18446744071562067968) (GUEST_OS linux) (HYPERCALL_PAGE 18446744071564189696) (LOADER generic) (ENTRY 18446744071564165120) (XEN_VERSION xen-3.0)))", 'name': 'student038'}
>
> [2009-12-16 00:12:55 4273] DEBUG (XendDomainInfo:1622) Storing domain details: {'console/ring-ref': '431020', 'image/entry': '18446744071564165120', 'console/port': '2', 'store/ring-ref': '431021', 'image/loader': 'generic', 'vm': '/vm/d297fda1-d5fe-e7a6-4925-f7aa8a706bd3', 'control/platform-feature-multiprocessor-suspend': '1', 'image/guest-os': 'linux', 'image/features/writable-descriptor-tables': '1', 'image/virt-base': '18446744071562067968', 'memory/target': '307200', 'image/guest-version': '2.6', 'image/features/supervisor-mode-kernel': '1', 'console/limit': '1048576', 'image/paddr-offset': '18446744071562067968', 'image/hypercall-page': '18446744071564189696', 'cpu/0/availability': 'online', 'image/features/pae-pgdir-above-4gb': '1', 'image/features/writable-page-tables': '1', 'console/type': 'xenconsoled', 'image/features/auto-translated-physmap': '1', 'name': 'student038', 'domid': '21', 'image/xen-version': 'xen-3.0', 'store/port': '1'}
>
> [2009-12-16 00:12:55 4273] DEBUG (DevController:95) DevController: writing {'protocol': 'x86_64-abi', 'state': '1', 'backend-id': '0', 'backend': '/local/domain/0/backend/console/21/0'} to /local/domain/21/device/console/0.
>
> [2009-12-16 00:12:55 4273] DEBUG (DevController:97) DevController: writing {'domain': 'student038', 'frontend': '/local/domain/21/device/console/0', 'uuid': '71ef139a-a1a1-f633-813a-3bd97435d291', 'frontend-id': '21', 'state': '1', 'location': '2', 'online': '1', 'protocol': 'vt100'} to /local/domain/0/backend/console/21/0.
>
> [2009-12-16 00:12:55 4273] DEBUG (XendDomainInfo:1709) XendDomainInfo.handleShutdownWatch
> [2009-12-16 00:12:55 4273] DEBUG (DevController:139) Waiting for devices vif.
> [2009-12-16 00:12:55 4273] DEBUG (DevController:144) Waiting for 0.
>
> [2009-12-16 00:12:55 4273] DEBUG (DevController:629) hotplugStatusCallback /local/domain/0/backend/vif/21/0/hotplug-status.
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:2724) XendDomainInfo.destroy: domid=21
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:2199) Destroying device model
>
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:2206) Releasing devices
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:2219) Removing vif/0
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:1134) XendDomainInfo.destroyDevice: deviceClass = vif, device = vif/0
>
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:2219) Removing vbd/51712
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:1134) XendDomainInfo.destroyDevice: deviceClass = tap, device = vbd/51712
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:2219) Removing vbd/2064
>
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:1134) XendDomainInfo.destroyDevice: deviceClass = tap, device = vbd/2064
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:2219) Removing console/0
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:1134) XendDomainInfo.destroyDevice: deviceClass = console, device = console/0
>
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:2204) No device model
> [2009-12-16 00:13:09 4273] DEBUG (XendDomainInfo:2206) Releasing devices

Any ideas why I can't run a DomU off a ramdisk? And even if that isn't possible why doesn't it muck up the rest of the DomUs? This is the message I get after it returns me to the command prompt.

> [root@server ~]# Error: Device 0 (vif) could not be connected. Hotplug scripts not working.


Grant McWilliams

Some people, when confronted with a problem, think "I know, I'll use Windows." 
Now they have two problems.

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