[CentOS-virt] Fwd: Building Xen on RHEL7

Sun Dec 22 07:32:04 UTC 2013
Nico Kadel-Garcia <nkadel at gmail.com>

On Sun, Dec 22, 2013 at 1:30 AM, Peter <peter at pajamian.dhs.org> wrote:
> On 12/22/2013 04:33 PM, Nico Kadel-Garcia wrote:
>> My first thought on seeing this thread was "Is there some reason to
>> compile from source, rather than from an SRPM, say those at
>> http://dev.centos.org/centos/6/xen-c6/SRPMS/ ?"
> My thinking is that the sources from F19 would be better since RHEL7 is
> based on F19 they would be a lot closer to RHEL7 than the CentOS 6 Xen
> sources, although both would probably build with no modifications at all.

That's fair., and a good point. However, the CentOS 6 tools did have
some issues, as mentioned below..

>> with the caveat that it did not have a "gcc"
>> dependencies, which I've added to a .spec file,
> gcc is considered to be part of the standard build toolset and as such
> is not required to be listed as a dependency in any spec file.

Part of a standard build toolset or not, it needs to be mentioned. The
dev86 SRPM was pretty old, admittedly. But Fedora, and EPEL, and RHEL,
all build their  RPM's with "mock" and "koji" these days, and gcc is
*not* part of the basic build environment. There are reasons, having
to do with cross-compilation and alternative compiler toolchains. So
RHEL, Fedora, and EPEL RPM's all specify "cc" or "gcc" as needed,

Do take a good look at those Fedora SRPM's if you think I'm kidding..

>> and the .spec file for
>> dev86 and for Xen both have badly formatted dates in the "%changelog"
>> stanza. RHEL 7 is much less tolerant of this  than RHEL 6 was. Again,
>> I've edited some .spec files and will try to submit some patches if I
>> can fiind time.
> The F19 spec files should be fully compliant with the EL7 guidelines.

Quite right, and good point. For the ctntos-virt world, I partly
thought I'd work from the centos-xen published tools. Again, you make
a good point..

>> Once I'd satisfied all the dependencies for the SRPM, I was able to
>> build the Xen 4.3.1  tarball pretty easily. It just didn't work well
>> to plug the tarball into the old  SRPM  and .spec file.
> Admittedly F19 comes with Xen 4.2.3, rawhide comes with 4.3.1, though,
> and can probably be directly rebuilt for EL7 without any fuss.
>> But with all that said: why are you bothering with Xen when RHEL and
>> thus CentOS have KVM support built right in? Is there some feature you
>> require that isn't available in the built-in KVM support?
> Some people like Xen, people like a choice, and it's not all that
> difficult to add Xen to EL7 anyways.  There's no reason to exclude it
> just because upstream made a political decision.

Sure. But don't make a choice just to make a different choice, and I'
didn't suggest excluding it. I was just asking why someone who was
unfamilar with RPM building was burning their cycles building from
scratch. I do it myself, but don't recommend it when there are tools
already availble. And you hd a *very* good point about working with
the Fedora tools!