Re: [Xen-devel] [stage1-xen PATCH v1 06/10] build/fedora: Add `xen-unstable-runit/*` scripts

[Rajiv Ranganath <rajiv.ranganath@xxxxxxxxxxx>]

On Tue, Sep 12 2017 at 04:38:19 AM, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> 
wrote:
> On 11/09/2017 21:20, Stefano Stabellini wrote:

[...]

>> My only concern is about diverging from the upstream Xen codebase. I
>> think the runit scripts should call xencommons underneath. If xencommons
>> cannot cope with being called from runit, we could make changes to
>> xencommon in xen.git to make it so.
>>
>> Otherwise, we will end up in a situation such as:
>> - xen.git changes xencommons
>> - we don't notice
>> - we upgrade Xen version
>> - stage1-xen doesn't work anymore
>>
>> If we used xencommons underneath we would avoid this, and it looks like
>> xencommons could be made to work well with runit.
>
> If possible, upstream Xen should be made to be compatible with runit
> (this would be the ideal case). If not, upstream Xen should contain
> different styles of these files, which are selected between by a
> ./configure option (this is suboptimal, but better than locally
> forking). This offers the greatest chance that updates to one don't
> cause the other to be stale.

I agree that it would be beneficial to have upstream Xen support for
runit. However, runit is packaged differently in every distro.

We work around this issue by packaging our own version of runit [1].
Fedora does not include runit in its repositories. That helps because we
don't have to worry about conflicting with distro packaged runit.

One option to consider is for xen project to package its own version of
runit for major distros (we will have one for Fedora in stage1-xen), and
use that as the basis for runit support.

Since stage1-xen is still under development, maybe we can use runit in
stage1-xen as a testing ground. If things work out well, we can then see
how best to integrate with xencommons or add a configure option.

By then we will also know if there is broader community interest in
having runit support in xen.

As to changes to xencommons breaking stage1-xen, as we get closer to
stable release, we probably will have integration tests to catch this
and many other things! :-)

Best,
Rajiv

[1]: https://github.com/lambda-linux-fedora/runit/tree/ver-2.1.2-1.1.fc25

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