[libvirt] [PATCH] qemu: work around dash 0.5.5 bug in managed save

[Eric Blake]

On 10/25/2010 06:28 PM, Justin Clift wrote:
> On 10/23/2010 10:29 AM, Eric Blake wrote:
>> * configure.ac (VIR_WRAPPER_SHELL): Define to a replacement shell,
>> if /bin/sh is broken on<>  redirection.
>> * src/qemu/qemu_monitor.h (VIR_WRAPPER_SHELL_PREFIX)
>> (VIR_WRAPPER_SHELL_SUFFIX): New macros.
>> * src/qemu/qemu_monitor_text.c (qemuMonitorTextMigrateToFile): Use
>> them.
>> * src/qemu/qemu_monitor_json.c (qemuMonitorJSONMigrateToFile):
>> Likewise.
>> ---
>>
>> Took longer than I thought, but this should do the trick with no
>> overhead on decent systems, and while still avoiding buggy dash ==
>> /bin/sh with something that works elsewhere.
>>
>> This passes for me on Fedora, where /bin/sh is bash; testing on
>> Ubuntu or other debian-based system where /bin/sh is dash 0.5.5
>> would be appreciated.
>
> No obvious errors crop up when testing this on Ubuntu 10.04:
>
>    virsh # managedsave 1
>    Domain 1 state saved by libvirt

Thanks for testing, and for Stefan's review.  I've pushed this now.

> As a usability thing though, there doesn't seem to be a matching
> "managedrestore" command in virsh, and the "help managedsave"
> command is bit light on "how do we restart a saved domain?":
>
>    # help managedsave
>      NAME
>        managedsave - managed save of a domain state
>
>      SYNOPSIS
>        managedsave<domain>
>
>      DESCRIPTION
>        Save and stop a running domain, so libvirt can restart it from
>        the same state

Maybe wording along these lines would help:

help managedsave
...
Save and stop a running domain, so the next start will reuse the same state.

help start
...
Start a domain, either from the last managedsave state, or via a fresh boot.

> Are we supposed to restart it using "start" or something?  (we need
> to mention this, which I can follow up with a patch)

Yes, a followup patch would be nice.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org