Xen ARM TODO: Difference between revisions
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== In progress == |
== In progress == |
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== Known Bugs == |
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=== General === |
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==== Domain 0 memory limitation due to 1:1 mapping ==== |
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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: |
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* http://lists.xen.org/archives/html/xen-devel/2014-01/msg00885.html |
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This should be addressed in a future release by supporting multiple memory banks for dom0. |
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=== Versatile Express === |
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=== Arndale Board === |
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== Open Work Items == |
== Open Work Items == |
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|Project=vGIC interrupt prioritisation |
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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. |
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{{Open Project |
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|Project=VCPU virtual time support |
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|Desc=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. |
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}} |
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{{Open Project |
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|Project=IOMMU support in Xen |
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|Desc= |
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write a driver in Xen for the ARM System Memory Management Unit (SMMU), use it to assign devices to Dom0. |
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}} |
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{{Open Project |
{{Open Project |
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|Desc= |
|Desc= |
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Make VM save/restore and VM migration work on ARM. |
Make VM save/restore and VM migration work on ARM. |
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|References= |
|References=An initial prototype was written a couple of years ago for arm32 but never completed: http://lists.xen.org/archives/html/xen-devel/2014-06/msg02076.html |
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}} |
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{{Open Project |
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|Project=Use Superpage mappings for P2M |
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|Desc= |
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Currently we use 4K pages everywhere. Xen should attempt to use 2MB mappings in the P2M wherever possible. |
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This will have significant performance benefits. |
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Need to do 2MB ballooning too. |
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}} |
}} |
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{{Open Project |
{{Open Project |
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|Project= |
|Project=PCI device assignment to DomUs |
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|Desc= |
|Desc= |
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Assign one or more devices to an unprivileged guest, re-program the SMMU accordingly. |
Assign one or more devices to an unprivileged guest, re-program the SMMU accordingly. |
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{{Open Project |
{{Open Project |
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|Project= |
|Project=ITS support |
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|Desc=Current Xen on ARM does not popular the wallclock time fields of the shared info with anything useful. It should do so... |
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Physical and virtual ITS support for GICv3. |
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}} |
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|References=Work underway: http://marc.info/?i=1426775889-29442-1-git-send-email-vijay.kilari%40gmail.com |
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{{Open Project |
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|Project=Support GIC v3 |
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|Desc=New hardware will come with GIC v3. Currently Xen only support GIC v2 |
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}} |
}} |
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|References=http://lists.xen.org/archives/html/xen-devel/2014-02/msg01880.html |
|References=http://lists.xen.org/archives/html/xen-devel/2014-02/msg01880.html |
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}} |
}} |
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|Project=Investigation on HCR.FB |
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|Desc=Setting HCR.FB will upgrade local flush instructions (TLB, instruction cache, branch predictor) to innershareable. It would be nice to benchmark the performance impact on a UP-aware kernel and see if this could be reduced by flushing when a vCPU is migrating to another physical CPUs. |
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[[Category:XenARM]] |
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Latest revision as of 10:22, 27 April 2016
This is a list of open work items and known bugs for the Xen on ARM with virtualization extension project.
In progress
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: An initial prototype was written a couple of years ago for arm32 but never completed: http://lists.xen.org/archives/html/xen-devel/2014-06/msg02076.html |
PCI 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. |
ITS support
| Contact: xen-devel@lists.xen.org |
| Description: Physical and virtual ITS support for GICv3. |
| References: Work underway: http://marc.info/?i=1426775889-29442-1-git-send-email-vijay.kilari%40gmail.com |
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 |
Investigation on HCR.FB
| Contact: xen-devel@lists.xen.org |
| Description: Setting HCR.FB will upgrade local flush instructions (TLB, instruction cache, branch predictor) to innershareable. It would be nice to benchmark the performance impact on a UP-aware kernel and see if this could be reduced by flushing when a vCPU is migrating to another physical CPUs. |
| References: http://lists.xen.org/archives/html/xen-devel/2016-04/msg03157.html |
