Re: [Xen-devel] Improve build system for offline environments

[George Dunlap <dunlapg@xxxxxxxxx>]

On Fri, May 3, 2019 at 1:55 PM Mathieu Tarral
<mathieu.tarral@xxxxxxxxxxxxxx> wrote:
>
> Hi,
>
> As stated by the documentation:
> "_Xen Project downloads various dependencies at build time_"
>
> This makes Xen a difficult project to work with in an offline environment.

There are lots of people who would like to see this changed.  It's
just not clear:

1. What the best solution would be, and
2. Who would do the work.

FWIW I think most distros have locked-off build systems.  How it's
normally done is:

1. Disable most functionality (seabios, ovmf, &c) and build it in a
separate package
2. For subtrees you do need, make a tarball and un-tar them as part of
the build process.

You can take a look at how this is done for the the CentOS Xen packages here:

https://github.com/CentOS-virt7/xen

> Thanks to the IRC channel, I heard of the command
> `make subtree-force-update-all`
> (We could document this option in the wiki "Compiling Xen From Source")
>
> However, the overall process stays problematic:
>
> 1. the target 'subtree-force-update-all' implies that you can run a 
> ./configure,
> otherwise you will get the following error:
>
> make[1]: Entering directory '~/xen/tools/'
> ~/xen/tools/../tools/Rules.mk:258: *** You have to run ./configure before 
> building or installing the tools. Stop.
>
> This is sometimes not possible because you are in a download-oriented
> and locked environment, and therefore lack the system dependencies required 
> for the configure.
>
> Also you don't have the root privileges to install them.

But it will *also* fail to build (say) qemu in this situation, since
it's in the tools directory, won't it?  If the download fails due to
`configure` failing, how would the build succeed even if download
didn't depend on `configure`?

> This is why I would like to start a discussion on how to
> improve the situation for those working in an air-gapped network environment.

Any chance you could make it to the Xen Developer Summit?  We'll
probably have a session on how to improve the build system:

https://design-sessions.xenproject.org/uid/discussion/disc_CqjX8fzeQ7MqifkCYczE/view

 -George

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