CentOS virt - Jan 2015 - Building Xen 4.4 rpms for centos7

Hello,

Now that the Xen 4.4.1 rpms + libvirt 1.2.10 rpms for CentOS 6 seem to be in
good shape
it would be a good time to start experimenting with el7 builds aswell.

I think it's best to start with the same set of packages we have for el6,
and just do the minimum required changes to get them working on centos7.

That probably means fixing some dependencies in the spec file, and some changes
for systemd support.

Note that all those changes are already done in Fedora 21 Xen rpms, for example:
ftp://ftp.funet.fi/pub/mirrors/fedora.redhat.com/pub/fedora/linux/updates/21/SRPMS/x/xen-4.4.1-12.fc21.src.rpm

A few months ago I also saw a Xen 4.4 el7 rpms port, so we could find those
src.rpms aswell.


And then there's the dom0 kernel.. Stock rhel7/centos7 is based on Linux
3.10 kernel,
so we probably can use the exact same 3.10.63 kernel we have today for CentOS 6
Xen.

Any thoughts?


-- Pasi

On Tue, Jan 20, 2015 at 2:10 PM, Pasi K?rkk?inen <pasik at iki.fi>
wrote:
> Hello,
>
> Now that the Xen 4.4.1 rpms + libvirt 1.2.10 rpms for CentOS 6 seem to be
in good shape
> it would be a good time to start experimenting with el7 builds aswell.
>
> I think it's best to start with the same set of packages we have for
el6,
> and just do the minimum required changes to get them working on centos7.
>
> That probably means fixing some dependencies in the spec file, and some
changes for systemd support.
>
> Note that all those changes are already done in Fedora 21 Xen rpms, for
example:
>
ftp://ftp.funet.fi/pub/mirrors/fedora.redhat.com/pub/fedora/linux/updates/21/SRPMS/x/xen-4.4.1-12.fc21.src.rpm
>
> A few months ago I also saw a Xen 4.4 el7 rpms port, so we could find those
src.rpms aswell.
>
>
> And then there's the dom0 kernel.. Stock rhel7/centos7 is based on
Linux 3.10 kernel,
> so we probably can use the exact same 3.10.63 kernel we have today for
CentOS 6 Xen.
>
> Any thoughts?
Sounds like a plan.  The main thing I'm waiting on is a way to build
the kernel that won't clobber the Docker C7 kernel. :-)

 -George

On 01/20/2015 08:10 AM, Pasi K?rkk?inen wrote:
> Hello,
> 
> Now that the Xen 4.4.1 rpms + libvirt 1.2.10 rpms for CentOS 6 seem to be
in good shape
> it would be a good time to start experimenting with el7 builds aswell.
> 
> I think it's best to start with the same set of packages we have for
el6,
> and just do the minimum required changes to get them working on centos7.
> 
> That probably means fixing some dependencies in the spec file, and some
changes for systemd support.
> 
> Note that all those changes are already done in Fedora 21 Xen rpms, for
example:
>
ftp://ftp.funet.fi/pub/mirrors/fedora.redhat.com/pub/fedora/linux/updates/21/SRPMS/x/xen-4.4.1-12.fc21.src.rpm
> 
> A few months ago I also saw a Xen 4.4 el7 rpms port, so we could find those
src.rpms aswell.
> 
Agreed on this too .. let's use as much the same as we can, and we can
use %if statements in the SPEC to differentiate el6 and el7 things, if
necessary.  systemd versus init and maybe some version number changes
for buildrequires should be the changes we need to be concerned about.
> 
> And then there's the dom0 kernel.. Stock rhel7/centos7 is based on
Linux 3.10 kernel,
> so we probably can use the exact same 3.10.63 kernel we have today for
CentOS 6 Xen.
I agree that we can likely use the current centos-6 kernel.  We do need
to decide when we want to shift the kernel to 3.14 .. the support for
3.10 as a LTS kernel ends in September 2015 (so 9 months).

https://www.kernel.org/category/releases.html

We can try to take the RH 3.10 el7 kernel, mod it for xen, and use it ..
or we can shift to 3.14.x and that buys us at least one more year .. or
wait until they name the next LTS kernel and go for that.  Likely the
next LTS kernel will be the easiest option (the RH modified kernel will
not support xen and rolling in stuff externally will be hard because of
the backports RH does to the kernel (things that go into a standard
kernel will not apply cleanly to the RH kernel).

But, I agree lets try to use the el6 kernel for xen el7 too .. and we
can switch both kernels as required later.

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On Tue, Jan 20, 2015 at 2:35 PM, Johnny Hughes <johnny at centos.org>
wrote:
> On 01/20/2015 08:10 AM, Pasi K?rkk?inen wrote:
>> Hello,
>>
>> Now that the Xen 4.4.1 rpms + libvirt 1.2.10 rpms for CentOS 6 seem to
be in good shape
>> it would be a good time to start experimenting with el7 builds aswell.
>>
>> I think it's best to start with the same set of packages we have
for el6,
>> and just do the minimum required changes to get them working on
centos7.
>>
>> That probably means fixing some dependencies in the spec file, and some
changes for systemd support.
>>
>> Note that all those changes are already done in Fedora 21 Xen rpms, for
example:
>>
ftp://ftp.funet.fi/pub/mirrors/fedora.redhat.com/pub/fedora/linux/updates/21/SRPMS/x/xen-4.4.1-12.fc21.src.rpm
>>
>> A few months ago I also saw a Xen 4.4 el7 rpms port, so we could find
those src.rpms aswell.
>>
>
> Agreed on this too .. let's use as much the same as we can, and we can
> use %if statements in the SPEC to differentiate el6 and el7 things, if
> necessary.  systemd versus init and maybe some version number changes
> for buildrequires should be the changes we need to be concerned about.
>
>>
>> And then there's the dom0 kernel.. Stock rhel7/centos7 is based on
Linux 3.10 kernel,
>> so we probably can use the exact same 3.10.63 kernel we have today for
CentOS 6 Xen.
>
> I agree that we can likely use the current centos-6 kernel.  We do need
> to decide when we want to shift the kernel to 3.14 .. the support for
> 3.10 as a LTS kernel ends in September 2015 (so 9 months).
I intend to do this as soon as I have time; but ATM I've got probably
less than one day a week to devote to it, so it may be slow.
> https://www.kernel.org/category/releases.html
>
> We can try to take the RH 3.10 el7 kernel, mod it for xen, and use it ..
> or we can shift to 3.14.x and that buys us at least one more year .. or
> wait until they name the next LTS kernel and go for that.  Likely the
> next LTS kernel will be the easiest option (the RH modified kernel will
> not support xen and rolling in stuff externally will be hard because of
> the backports RH does to the kernel (things that go into a standard
> kernel will not apply cleanly to the RH kernel).
Sticking with the stable upstream kernels would allow us to easily get
fixes and updates to Xen-specific issues, rather than having to
manually port them over.

 -George

On Tue, Jan 20, 2015 at 08:35:31AM -0600, Johnny Hughes
wrote:
> On 01/20/2015 08:10 AM, Pasi K?rkk?inen wrote:
> > Hello,
> > 
> > Now that the Xen 4.4.1 rpms + libvirt 1.2.10 rpms for CentOS 6 seem to
be in good shape
> > it would be a good time to start experimenting with el7 builds aswell.
> > 
> > I think it's best to start with the same set of packages we have
for el6,
> > and just do the minimum required changes to get them working on
centos7.
> > 
> > That probably means fixing some dependencies in the spec file, and
some changes for systemd support.
> > 
> > Note that all those changes are already done in Fedora 21 Xen rpms,
for example:
> >
ftp://ftp.funet.fi/pub/mirrors/fedora.redhat.com/pub/fedora/linux/updates/21/SRPMS/x/xen-4.4.1-12.fc21.src.rpm
> > 
> > A few months ago I also saw a Xen 4.4 el7 rpms port, so we could find
those src.rpms aswell.
> > 
> 
> Agreed on this too .. let's use as much the same as we can, and we can
> use %if statements in the SPEC to differentiate el6 and el7 things, if
> necessary.  systemd versus init and maybe some version number changes
> for buildrequires should be the changes we need to be concerned about.
>
Yep!
 
> > 
> > And then there's the dom0 kernel.. Stock rhel7/centos7 is based on
Linux 3.10 kernel,
> > so we probably can use the exact same 3.10.63 kernel we have today for
CentOS 6 Xen.
> 
> I agree that we can likely use the current centos-6 kernel.  We do need
> to decide when we want to shift the kernel to 3.14 .. the support for
> 3.10 as a LTS kernel ends in September 2015 (so 9 months).
> 
> https://www.kernel.org/category/releases.html
> 
> We can try to take the RH 3.10 el7 kernel, mod it for xen, and use it ..
> or we can shift to 3.14.x and that buys us at least one more year .. or
> wait until they name the next LTS kernel and go for that.  Likely the
> next LTS kernel will be the easiest option (the RH modified kernel will
> not support xen and rolling in stuff externally will be hard because of
> the backports RH does to the kernel (things that go into a standard
> kernel will not apply cleanly to the RH kernel).
> 
> But, I agree lets try to use the el6 kernel for xen el7 too .. and we
> can switch both kernels as required later.
> 
Yeah we're not in a hurry with the dom0 kernel. Current Linux 3.10.x seems
to work fine atm.

Let's focus on getting the current rpms built for el7,
and then later we can update both el6 and el7 to later kernel/versions.


-- Pasi