Re: [XEN PATCH] tools/xenstore: Log xenstored build ID on startup

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 13/11/2020 16:55, Bjoern Doebel wrote:
>
> On 13.11.20 15:30, Andrew Cooper wrote:
>> On 13/11/2020 14:18, Bjoern Doebel wrote:
>>> Right now we do not have a mechanism to determine the version of the
>>> currently running xenstored at runtime. As xenstored runs throughout
>>> the
>>> lifetime of a Xen host, this may lead to problems when newer user space
>>> builds are staged. Then, the running xenstored will no longer match the
>>> version of the installed xenstored.
>>>
>>> To allow users to always identify the running version of xenstored, add
>>> a linker-generated unique build ID to every xenstored build. Add
>>> functionality to log this build ID into a file upon service startup.
>>>
>>> Signed-off-by: Bjoern Doebel <doebel@xxxxxxxxx>
>>> Reviewed-by: Martin Mazein <amazein@xxxxxxxxx>
>>> Reviewed-by: Paul Durrant <pdurrant@xxxxxxxxxxxx>
>> I understand the problem you're trying to solve, but why is this
>> anything more than just enabling build-id's by default across tools/ ?
>>
>> There are already standard ways of interacting with the build id of
>> running executables on the system.  I'd strongly discourage doing
>> anything custom in xenstored specifically.
> May I ask what tooling you would use to interact with a running
> process' buildid?

Amongst other things, yes.  Although as Juergen points out, we want
something which works with stub domains as well, and "normal userspace
tools" won't cut it there.

I still think a first patch in this series should be to turn build-id's
on by default if supported by the toolchain, generally.

~Andrew