Modular Kernel Packaging for Cloud

Sandro "red" Mathys red at
Fri Mar 14 07:42:11 UTC 2014

On Fri, Mar 14, 2014 at 3:46 PM, Sandro "red" Mathys
<red at> wrote:
> On Fri, Mar 7, 2014 at 3:14 AM, Josh Boyer <jwboyer at> wrote:
>> On Thu, Mar 6, 2014 at 11:18 AM, Matthew Miller
>> <mattdm at> wrote:
>>> On Thu, Mar 06, 2014 at 10:33:47AM -0500, Josh Boyer wrote:
>>>> Right.  When I said I had kernel-core and kernel-drivers, I wasn't
>>>> being theoretical.  I already did the work in the spec file to split
>>>> it into kernel-core and kernel-drivers.  The kernel package becomes a
>>>> metapackage that requires the other two, so that existing installs and
>>>> anaconda don't have to change (assuming I did thinks correctly).
>>>> Cloud can just specify kernel-core in the kickstart or whatever.
>>> Does yum's kernel-handling magic need to change to handle this? Probably you
>>> have already thought of that.
>> I gave it some thought.  I haven't tested anything.  Existing magic
>> should work for most installs since there's still a "kernel" package
>> and that's what yum keys off of.  If/when we do this, I'll certainly
>> test more carefully to make sure.
>> That brings up a question though, how often would cloud expect to do a
>> yum update of individual packages as opposed to just updating the
>> entire image?  If we expect the 3 kernel magic to work there, then
>> some changes to yum/dnf may be required given that Cloud would be
>> explicitly specifying "kernel-core" and not "kernel".
> Yesterday, I updated to Josh's 2.5 kernel, then I removed kernel and
> kernel-drivers, only leaving kernel-core. Today, I again updates, this
> time 3.8 being available. Now guess what? The "install instead of
> update" magic worked. I know have both kernel-core packages. So I
> figure yum works this magic with any kernel* package.
> So it would seem no change to yum is necessary after all. Going to
> reach out to the yum developers to find out the details. Also, whether
> dnf does the exact same or not.

Okay, I poked around in the yum source, yum docs and kernel packages a
bit. So yum (and some testing confirms, dnf too) does not check the
package names but the provides (obviously, thinking about it). The
actual magic being that both kernel and kernel-core provide "kernel".
If that is still the case once the patch is merged from copr to
Fedora, no changes to yum or dnf should become necessary. Which would
probably leave us with "anaconda must allow for installing only just
kernel-core instead of kernel (when kickstarting)" as the only
necessary change to Fedora. I guess.

-- Sandro

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