[openstack-dev] [ironic] Kernel parameters needed to boot from iscsi

Dmitry Tantsur dtantsur at redhat.com
Wed Oct 25 12:03:34 UTC 2017

(ooops, I somehow missed this email. sorry!)

Hi Yolanda,

On 10/16/2017 11:06 AM, Yolanda Robla Mota wrote:
> Hi
> Recently i've been helping some customers in the boot from ISCSI feature. So far 
> everything was working, but we had a problem when booting the deployment image.
> It needed specifically a flag rd.iscsi.ibft=1 rd.iscsi.firmware=1 in the grub 
> commands. But as the generated deployment image doesn't contain these flags, 
> ISCSI was not booting properly. For other hardware setups, different flags may 
> be needed.

Note that we only support BFV in the form of booting from a cinder volume 
officially. We haven't looked into iBFV in depth.

> The solution was to manually execute a virt-customize on the deployment image to 
> hardcode these parameters.
> I wonder if we can add some feature in Ironic to support it. We have discussed 
> about kernel parameters several times. But at this time, it affects ISCSI 
> booting. Not having a way in Ironic to customize these parameters forces to 
> manual workarounds.

This has been discussed several times, and every time the idea of making it a 
generic feature was rejected. There is an option to configure kernel parameters 
for PXE boot. However, apparently, you cannot add rd.iscsi.firmware=1 if you 
don't use iSCSI, it will fail to boot (Derek told me that, I did not check). If 
your deployment only uses iSCSI - you can modify [pxe]pxe_append_params in your 
ironic.conf to include it.

> So can we reconsider the proposal to add kernel parameters there? It could be a 
> settable argument (driver_info/kernel_args), and then the IPA could set the 
> parameters properly on the image. Or any other option is welcome.
> What are your thoughts there?

Well, we could probably do that *for IPA only*. Something like 
driver_info/deploy_image_append_params. This is less controversial than doing 
that for user instances, as we fully control the IPA boot. If you want to work 
on it, let's start with a detailed RFE please.

> Thanks
> -- 
> Yolanda Robla Mota
> Principal Software Engineer, RHCE
> Red Hat
> <https://www.redhat.com>
> C/Avellana 213
> Urb Portugal
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