[libvirt] [Xen-devel] [PATCH 00/12] libxl: fork: SIGCHLD flexibility
Jim Fehlig
jfehlig at suse.com
Thu Jan 30 16:14:01 UTC 2014
Daniel P. Berrange wrote:
> On Mon, Jan 27, 2014 at 06:39:36PM -0700, Jim Fehlig wrote:
>
>> [Adding libvirt list...]
>>
>> Ian Jackson wrote:
>>
>>> Jim Fehlig writes ("Re: [Xen-devel] [PATCH 00/12] libxl: fork: SIGCHLD flexibility"):
>>>
>
> BTW, I meant to ask before - what is the SIGCHLD reference about in the
> subject line ?
>
This is related to child processes started by libxl. E.g. running a
bootloader when creating PV VMs, running a save/restore helper when
saving/restoring a VM, etc.
> libvirt drivers that live inside libvirtd should never use or rely on
> the SIGCHLD signal at all. All VM processes started by libvirtd ought
> to be fully daemonized so that their parent is pid 1 / init. This ensures
> that the libvirtd daemon can be restarted without all the VMs getting
> reaped. Once the VMs are reparented to init, then libvirt or library
> code it uses has no way of ever receiving SIGCHLD.
>
Nod. VMs are "daemonized", in the context of Xen. Once running,
libvirtd can be restarted without reaping them.
Regards,
Jim
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