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REQUEST: Build 3.11 kernel with VFIO enabled by default

Asked by GizmoChicken

Following a tutorial that I found on the Arch Linux forums, I've been experimenting with VGA passthrough using VFIO with KVM. (Please see https://bbs.archlinux.org/viewtopic.php?id=162768 for details.) So far, I've had a fair amount of success using Ubuntu 13.10, combined with the mainline 3.11 RC4 kernel, as host.

One problem with using the mainline kernel is that, although one of the four requisite kernel components is already built into the kernel, the other three requisite kernel components must be run as modules. And although running them as modules has worked for me, many have reported that VFIO is much more stable when run from a custom kernel built to include all needed components.

Here is a portion of the configuration file for mainline kernel 3.11 RC4:

    CONFIG_VFIO_IOMMU_TYPE1=m
    CONFIG_VFIO=m
    CONFIG_VFIO_PCI=m
    CONFIG_VFIO_PCI_VGA=y

REQUEST: Please build future versions of the Ubuntu 3.11 kernel using a configuration file that includes the following:

    CONFIG_VFIO_IOMMU_TYPE1=y
    CONFIG_VFIO=y
    CONFIG_VFIO_PCI=y
    CONFIG_VFIO_PCI_VGA=y

Although still in early development, VFIO seems very promising and so my guess is that many will want to make use of it. I hope Ubuntu helps in this effort by rolling the above into its default 3.11 kernel.

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actionparsnip (andrew-woodhead666) said : 		#1

The 3.11 kernel isn't in Ubuntu. Saucy is up to 3.10 so I'm not sure how it can be added when it's not even part of the distribution.

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daniel CURTIS (anoda) said : 		#2

Hi. Andrew it seems, that 3.11 kernel (from version v3.11-rc1-saucy to 3.11-rc4-saucy - last modified on 04-Aug-2013) is already in Ubuntu. Please check: http://kernel.ubuntu.com/~kernel-ppa/mainline/

Best regards.

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GizmoChicken (gizmochicken) said : 		#3

@Andrew: Although daily builds of Saucy currently include the 3.10 kernel, daily builds will eventually include the 3.11 kernel, and Saucy will almost certainly be released with a 3.11 kernel in October. I am requesting that the 3.11 kernel, which will eventually find its way to Saucy, be built to include the above mentioned VFIO components. That is, I am making this request well in advance, while developers still have time to consider my request and make changes.

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actionparsnip (andrew-woodhead666) said : 		#4

Could report a bug then.

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daniel CURTIS (anoda) said : 		#5

Hi Gizmo. Maybe, you should reach a KernelTeam by e.g. mailing lists and there write your request? (just subscribe to <email address hidden>). Very interesting informations you will find also on KernelTeam Wiki: https://wiki.ubuntu.com/KernelTeam

Gizmo, are you thinking about something similar? I think, that it could be worth to write post, on their mailing list. Best regards.

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daniel CURTIS (anoda) said : 		#6

Argh. Sorry for a double posts, but I checked a CHANGES file for v3.11-rc1-saucy kernel for a notes about VFIO. There is a couple of changes, which include vfio:

,-----[ Alex Williamson (10) ]
| vfio: Convert type1 iommu to use rbtree
| vfio: hugepage support for vfio_iommu_type1
| vfio: Provide module option to disable vfio_iommu_type1 hugepage support
 `-----

and so on. That is only a three changes/fixes. It seems, that only *-rc1-saucy and *-rc4-saucy, are providing some changes about 'vfio'. Of course it is only for an informational purposes! I checked it just out of curiosity. Please remember that.

Best regards and sorry once again for a double posts.

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