Xen ARM TODO
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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
vGIC interrupt prioritisation
| Contact: xen-devel@lists.xen.org |
| Description: 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: Not specified, useful references. |
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. |
IOMMU support in Xen
| Contact: xen-devel@lists.xen.org |
| Description: write a driver in Xen for the ARM System Memory Management Unit (SMMU), use it to assign devices to Dom0. |
| References: Not specified, useful references. |
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 |
Use Superpage mappings for P2M
| Contact: xen-devel@lists.xen.org |
| Description: 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. |
| 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. |
