blktap module needed for kernel 4.16. kernel 4.16 needed for latest Ceph with bluestore backend.

olivierlambert

You too!

r1

Update -

Success in running kernel-4.16+ in dom0 with blktap2 driver + Ceph luminous version with bluestore backend.
Could isolate blktap2 driver from kernel to a loadable kernel module in form of blktap2-4.16.8-modules-1.0-1.x86_64.rpm
Can install any upstream kernel in dom0 but blktap2 needs to be built against same kernel else xapi won't start.

[root@client ~]# uname -a Linux client.enlight 4.16.13 #1 SMP Wed May 30 09:22:58 GMT 2018 x86_64 x86_64 x86_64 GNU/Linux

[root@client ~]# rpm -ivh blktap2-4.16.8-modules-1.0-1.x86_64.rpm
error: Failed dependencies: kernel-uname-r = 4.16.8 is needed by blktap2-4.16.8-modules-1.0-1.x86_64

So essentially to make it worth - the only option is to setup a continous build system that will build latest stable kernels and host either full upstream dom0 compatible kernel or just the blktap2 module... may be both

Time to rest blktap2 and move to the actual Ceph productivity integrations.

olivierlambert

We want to make this CI stuff, that we will be the goal of Sam, our new recruit coming in 20 days!

edit: @r1 you are obviously more than welcome aboard to help us on that!

r1

@olivierlambert Would you want to include this in that CI? May be on an experimental branch.

olivierlambert

I don't know yet, it's likely we'll have multiple CI, one for "stable", one for "experimental" with a lot of fun stuff inside

r1

Cool

I'll get the patch added to GitHub for open access till then.

r1

I added the patch on Github - I'm testing it in various systems.

If you are using RBDSR then use the extra flag device-config:rbd-mode=kernel while creating the PBD.

Cheers.

olivierlambert

Thanks!

Is there a way to get this upstream?

r1

I don't know yet.
I will try for centos-release-xen as its a SIG and maintains Xen specific dom0 kernel.

olivierlambert

The CentOS packaging of Xen is very different from XenServer/XCP-ng. "Upstream" for me meant XenServer, no CentOS (at least for a bit)

maxcuttins

@r1 Sorry Rushy,

Why did you create a patch instead of directly sent a pull request to the original blktap2 driver.
I'll say it's time to stop to make unofficial patches which can be overwritten by upstream updates.
Let's change the upstream directly.

https://github.com/xapi-project/blktap

r1

@maxcuttins There are two packages. User level blktap driver that you referred blktap and a builtin kernel driver blktap2. Said patch is against mainline kernel as additional driver.

You still need to have user land blktap from https://github.com/xapi-project/blktap
There are instructions lying around https://xcp-ng.org/forum/topic/122/how-to-build-blktap-from-sources/ to build user land blktap (its without patch).