Xen ARM TODO: Difference between revisions

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{{Open Project
{{Open Project
|Project=vGIC interrupt prioritisation
|Project=Save/restore and migration
|Desc=
|Desc=
⚫
Make VM save/restore and VM migration work on ARM.
Currently the vGIC only implements a very basic form of interrupt priority, in particular it is not able to preempt an inflight lower priority interrupt when a new higher priority one occurs. The emulation needs to consider the vCPUs current IAR as well as the priorities of pending and inflight interrupts.
⚫
|References=InProgress: http://lists.xen.org/archives/html/xen-devel/2013-10/msg00192.html
}}
}}


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}}
}}


{{Open Project
|Project=IOMMU support in Xen
|Desc=
write a driver in Xen for the ARM System Memory Management Unit (SMMU), use it to assign devices to Dom0.
|References=In Progress: http://lists.xen.org/archives/html/xen-devel/2014-02/msg00670.html
}}

{{Open Project
|Project=Save/restore and migration
|Desc=
⚫
Make VM save/restore and VM migration work on ARM.
⚫
|References=InProgress: http://lists.xen.org/archives/html/xen-devel/2013-10/msg00192.html
}}
{{Open Project
|Project=Use Superpage mappings for P2M
|Desc=
Currently we use 4K pages everywhere. Xen should attempt to use 2MB mappings in the P2M wherever possible.
This will have significant performance benefits.
Need to do 2MB ballooning too.
}}
{{Open Project
{{Open Project
|Project=Device assignment to DomUs
|Project=Device assignment to DomUs
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|Project=Expose Wallclock time to guests
|Project=Expose Wallclock time to guests
|Desc=Current Xen on ARM does not popular the wallclock time fields of the shared info with anything useful. It should do so...
|Desc=Current Xen on ARM does not popular the wallclock time fields of the shared info with anything useful. It should do so...
}}

{{Open Project
|Project=Support GIC v3
|Desc=New hardware will come with GIC v3. Currently Xen only support GIC v2
}}
}}


Revision as of 13:27, 6 May 2015

This is a list of open work items and known bugs for the Xen on ARM with virtualization extension project.


In progress

Known Bugs

General

Domain 0 memory limitation due to 1:1 mapping

The use of the 1:1 workaround for dom0's memory (needed on platforms without an I/O SMMU, which is currently all) limits the maximum size of dom0. By carefully positioning the Xen and initial kernel/initrd/dtb binaries at the top of RAM dom0 is able to make use of up to 1/2 of the host RAM. The remainder is available for guest use. In general dom0 should be made quite small anyway. For more information see: 

* http://lists.xen.org/archives/html/xen-devel/2013-12/msg02239.html
* http://lists.xen.org/archives/html/xen-devel/2014-01/msg00885.html

This should be addressed in a future release by supporting multiple memory banks for dom0.

Versatile Express

Arndale Board

Open Work Items

Save/restore and migration
Contact: xen-devel@lists.xen.org
Description: Make VM save/restore and VM migration work on ARM.
References: InProgress: http://lists.xen.org/archives/html/xen-devel/2013-10/msg00192.html

VCPU virtual time support
Contact: xen-devel@lists.xen.org
Description: Currently the concept of virtual time exposed to the guests is very simplistic and is just a static offset from physical time based on the time when the guest was started. We need to consider if this is actually what is needed/wanted and consider cases such as stolen time etc.
References: Not specified, useful references.

Device assignment to DomUs
Contact: xen-devel@lists.xen.org
Description: Assign one or more devices to an unprivileged guest, re-program the SMMU accordingly.
References: Not specified, useful references.

Expose Wallclock time to guests
Contact: xen-devel@lists.xen.org
Description: Current Xen on ARM does not popular the wallclock time fields of the shared info with anything useful. It should do so...
References: Not specified, useful references.

More flexible early printk support
Contact: xen-devel@lists.xen.org
Description: Allow a single Xen binary to support multiple platforms for early_printk Rather than parsing the DTB early in asm to get the command line it would probably be sufficient to have a magic hex byte at a specific offset which could be edited by a simple tool.
References: http://lists.xen.org/archives/html/xen-devel/2014-02/msg01880.html

Support for DT /chosen/stdout-path node
Contact: xen-devel@lists.xen.org
Description: ePAPR 1.1 3.5 defines the /chosen/stdout-path property which contains the path to the serial device as a string.

We could potentially make two uses of this:

  • Xen itself could use this property if it is present to set the default dtuart= option, saving users the hassle.
  • We could pass a suitable /chosen/stdout-path to dom0 to cause it to use hvc0 by default. This needs thinking through since hvc0 doesn't itself have a dt node.
References: https://www.power.org/documentation/epapr-version-1-1/ https://git.kernel.org/linus/a208ffd251d08ed7ba6bdf3ae1e423373fb12d3d https://git.kernel.org/linus/3482f2c52b77bf6596e24aae82e204a0603eba66
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