Re: [PATCH 2/3] Mini-OS: don't crash if no shutdown node is available

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 01/11/2023 4:42 pm, Juergen Gross wrote:
> On 01.11.23 17:38, Andrew Cooper wrote:
>> On 01/11/2023 9:00 am, Juergen Gross wrote:
>>> It might be perfectly fine not to have a control/shutdown Xenstore
>>> node. If this is the case, don't crash, but just terminate the
>>> shutdown thread after issuing a message that shutdown isn't available.
>>>
>>> In fini_shutdown() clearing the watch can result in an error now, in
>>> case the early exit above was taken. Just ignore this error now.
>>>
>>> Signed-off-by: Juergen Gross <jgross@suse.com>
>>
>> Which cases might we not have a control/shutdown node?
>
> Xenstore-stubdom. It should _never_ shutdown, and it isn't really under
> control of Xen tools (other than being created).
>
>> I'm all for coping better with its absence, but it's not a piece of the
>> Xen ABI which is optional.
>
> I'd like to differ here. See reasoning above.

If we're going to permit this configuration, then I think it needs an
extension to xenstore-paths to make it officially optional.

And I think it's reasonable to support, but I wouldn't go as far as
saying "never".  If you've cleaved the global xenstored in
twain/trine/etc, then individual parts of it can shut down normally.

~Andrew