Distros and Required Kernel/Initrd's

[Devan Goodwin]

Just trolling for info to see if anyone knows specifics about why
Cobbler requires an explicit kernel/initrd on distro's or if there's a
unified way they're used. (or expected to be used)

In digging around it seems that if you're doing a physical koan
--replace-self, the kernel/initrd specified will be used, although
there's also some code in there that will seek the correct pair out if
they're not specified or unusable.

In the case of a virt kickstart however (at least KVM) the
kernel/initrd isn't used at all, only the install tree is.

Asking around #cobbler-devel I heard that they may just be required
for memtest (not something I'm totally familiar with)

Just wondering if this raises any alarms for anyone, or if it's
something that needs fixing.  Let me know if you have any insight!

Thanks,

Devan

[Jeff Schroeder]

On Mon, Jan 11, 2010 at 7:33 AM, Devan Goodwin  wrote:
> Just trolling for info to see if anyone knows specifics about why
> Cobbler requires an explicit kernel/initrd on distro's or if there's a
> unified way they're used. (or expected to be used)
>
> In digging around it seems that if you're doing a physical koan
> --replace-self, the kernel/initrd specified will be used, although
> there's also some code in there that will seek the correct pair out if
> they're not specified or unusable.
>
> In the case of a virt kickstart however (at least KVM) the
> kernel/initrd isn't used at all, only the install tree is.
>
> Asking around #cobbler-devel I heard that they may just be required
> for memtest (not something I'm totally familiar with)
>
> Just wondering if this raises any alarms for anyone, or if it's
> something that needs fixing.  Let me know if you have any insight!

Can you explain what you mean a bit more? The distro is generally
sucked in from an install tree which (as a side effect) includes a
kernel / initrd combo. It would be quite nice to have the
kernel/initrd be per-profile instead of per-distro but things like
anaconda get really cranky when you don't use the kernel that matches
the install tree. Perhaps that is the reason for this?

[Devan Goodwin]

On Mon, Jan 11, 2010 at 12:22 PM, Jeff Schroeder  wrote:
> Can you explain what you mean a bit more? The distro is generally
> sucked in from an install tree which (as a side effect) includes a
> kernel / initrd combo. It would be quite nice to have the
> kernel/initrd be per-profile instead of per-distro but things like
> anaconda get really cranky when you don't use the kernel that matches
> the install tree. Perhaps that is the reason for this?

If you were to create a distro manually with something like this:

cobbler distro add --name="deleteme"
--ksmeta="tree=http://@@http_server@@/cblr/links/rhel-5.3-i386"
--kernel=/var/www/cobbler/ks_mirror/rhel-5.3/images/pxeboot/vmlinuz
--initrd=/var/www/cobbler/ks_mirror/rhel-5.3/images/pxeboot/initrd.img

Both the --kernel and --initrd are required options. You can get by
without specifying the tree.

If doing a physical replace-self kickstart, that kernel/initrd you
specified appear to be used. If doing a KVM/qemu kickstart, they're
ignored entirely and just the install tree is passed along to the virt
inst library.

Trying to check if something is off there, seems like the required
params should be used consistently, or not required. (or is everything
as it should be?)

Cheers,

Devan

[Vreman, Peter]

> > Can you explain what you mean a bit more? The distro is generally
> > sucked in from an install tree which (as a side effect) includes a
> > kernel / initrd combo. It would be quite nice to have the
> > kernel/initrd be per-profile instead of per-distro but things like
> > anaconda get really cranky when you don't use the kernel that matches
> > the install tree. Perhaps that is the reason for this?
>
> If you were to create a distro manually with something like this:
>
> cobbler distro add --name="deleteme"
> --ksmeta="tree=http://@@http_server@@/cblr/links/rhel-5.3-i386"
> --kernel=/var/www/cobbler/ks_mirror/rhel-5.3/images/pxeboot/vmlinuz
> --initrd=/var/www/cobbler/ks_mirror/rhel-5.3/images/pxeboot/initrd.img
>
> Both the --kernel and --initrd are required options. You can get by
> without specifying the tree.
>
> If doing a physical replace-self kickstart, that kernel/initrd you
> specified appear to be used. If doing a KVM/qemu kickstart, they're
> ignored entirely and just the install tree is passed along to the virt
> inst library.
>
> Trying to check if something is off there, seems like the required
> params should be used consistently, or not required. (or is everything
> as it should be?)

The initrd/kernel pair is also required for live CD booting.

Moving the initrd/kernel pair to profile then it must also be possible to create a profile
without a parent distro. That is currently not conform the design of cobbler.

Regards,
Peter

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