Xen 4.3 released [LWN.net]

Xen 4.3 released

Posted Jul 9, 2013 18:33 UTC (Tue) by ibukanov (subscriber, #3942)
Parent article: Xen 4.3 released

It is not clear if ARM support in XEN requires a hardware hypervisor mode or it could use paravirtualization without any special hardware support. In the former case it would rule out a possibility of running XEN on a Samsung ARM Chromebook. On that hardware, although the underlining CPU supports the hypervisor mode, the primary bootloader in ROM makes it impossible to use that.

to post comments

Xen 4.3 released

Posted Jul 10, 2013 7:43 UTC (Wed) by mzyngier (subscriber, #32898) [Link] (1 responses)

The hypervisor mode is reachable on the Chromebook.
It is just a matter of having a second-stage bootloader that switches the CPU to that mode.

And for the record, the Xen guys do run their hypervisor on the Exynos5 based Chromebook.

Xen 4.3 released

Posted Jul 10, 2013 11:27 UTC (Wed) by ibukanov (subscriber, #3942) [Link]

Thanks for the clarification! From https://lwn.net/Articles/557561/ I got an impression that it was the first stage ROM bootloader that prevents runing a hypervisor.

Xen 4.3 released

Posted Jul 11, 2013 14:08 UTC (Thu) by dunlapg (guest, #57764) [Link]

Xen for ARM does require the virtualization extensions. As others have pointed out, however, it can run on a Chromebook: that was in fact the first platform the team got Xen booting on, because that was the first publicly available hardware with the ARM virtualization extensions. (And, how can you resist the opportunity to expense a bunch of chromebooks?)

The general approach is to use the hardware virtualization and PV where it makes sense to do so. A lot of the pain experienced right now with the pvops kernel on x86 has to do with virtualizing aspects of the hardware that could easily be solved by using the HVM extensions. Having the opportunity to start with a "PVH" mode for ARM should make the whole Xen/Linux relationship much easier.

(See http://blog.xen.org/index.php/2012/10/23/the-paravirtuali... for background information on HVM and PV, and http://blog.xen.org/index.php/2012/10/31/the-paravirtuali... for more information on PVH mode, which is essentially the mode that Xen-for-ARM will start with.)