Re: [Publicity] Xen Project Hypervisor 4.5 blog

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 5 Jan 2015, Julien Grall wrote:
> On 04/01/15 22:53, Sarah Conway wrote:
> > 
> >   Hi everyone.
> 
> Hi Sarah,
> 
> Few comments on the ARM part below.
> 
> > 
> > ARM Hypervisor-Specific Updates
> > 
> > The ARM ecosystem operates differently to the x86 architecture â in
> > which ARM licensees design new chipsets and features and OEMs
> > manufacture platforms based on these specifications.
> > 
> > 
> > OEMs designing ARM based platforms determine what they need on the SoC â
> > that is the System On Chip. As such they can selectively enable or
> > disable certain functionality that they consider important (or
> > unimportant). ARM provides the Intellectual Property (IP) and standards
> > from which OEMs can further specialize and optimize. Therefore the list
> > of features that Xen Project Hypervisor supports on ARM is not for a
> > specific platform â but rather for functionality SoCs provide. New
> > updates include:
> > 
> > 
> >   *
> > 
> >     Support for more than 1TB guests.
> > 
> >   *
> > 
> >     The Generic Interrupt Controller (GIC) v3 is supported in Xen 4.5.
> >     v3 supports Message Signaled Interrupts (MSI), emulation of GICv3
> >     for guests â and most importantly â support for more 8 CPUS.
> 
> I think this item is confusing. While GICv3 supports MSI and more than 8
> CPUs. None of those has been implemented on Xen 4.5.

That is true. Maybe something like:

"The Generic Interrupt Controller (GIC) v3 is supported in Xen 4.5.
v3 is very important because it introduces support for Message Signaled
Interrupts (MSI), emulation of GICv3 for guests â and most importantly â
for more thn 8 CPUS. Many of the new features are not used by Xen yet
but the driver is on par with v2."



> >   *
> > 
> >     Power State Coordination Interface (PSCI) â important in the
> >     embedded environment where power consumption needs to be kept to the
> >     absolute minimum. It allows us to power down/up CPUS, suspend them, etc.
> 
> This was already supported in Xen 4.4. Though, we add support of PSCI
> 0.2 for the host.

We should just add "0.2" in the title of the paragraph.


> >   *
> > 
> >     UEFI booting. On ARM64 servers both U-Boot and UEFI can be used to
> >     boot the OS.
> > 
> >   *
> > 
> >     IOMMU support (SMMUv1). For isolation between guests, ARM hardware
> >     can come with an IOMMU chipset based on the SMMU specification.
> > 
> >   *
> > 
> >     Super Pages (2MB) support in Xen. Using super pages for the guest
> >     pseudo-physical to physical translation tables significantly
> >     improves overall guest performance.
> > 
> >   *
> > 
> >     Passthrough â the PCI passthrough features did not make on time, but
> >     doing passthrough of MMIO regions did. In the ARM world it is quite
> >     common to have no PCIe devices and to only access devices using MMIO
> >     regions. As such this feature allows us to have driver domains be in
> >     charge of network or storage devices.
> 
> Network and storage devices will likely use IRQ and DMA. While MMIO
> passthrough is fully implemented in Xen 4.5, IRQ and IOMMU suport for
> guest (necessary for DMA) has been deferred for Xen 4.6.

We could add something like "as long as they do not use DMA" at the end
of the paragraph. I am not sure whether it makes sense to go into the
level of details needed to explain the reason why it is so, in this blog
post.


> >   *
> > 
> >     Interrupt latency reduction: no maintenance interrupts. Please see
> >     Stefanoâs slides.
> > 
> > 
> > 
> > With these new features, the following motherboards
> > <http://wiki.xenproject.org/wiki/Xen_ARM_with_Virtualization_Extensions>are
> > now supported in Xen Project Hypervisor 4.5:
> > 
> >   *
> > 
> >     AMD Seattle
> > 
> >   *
> > 
> >     Broadcom 7445D0 A15
> > 
> >   *
> > 
> >     Midway (Calxeda)
> > 
> >   *
> > 
> >     Odroid-XU
> 
> The Odroid-Xu is based on the an Exynos5 processor. It might be
> interesting to merge this with the "Exynos5" item below.
> 
> >   *
> > 
> >     Vexpress (ARM Ltd.)
> > 
> >   *
> > 
> >     OMAP5, OMAP6, DRA7 (Texas Instrument)
> 
> What is OMAP6? I can't find a board
> 
> > 
> >   *
> > 
> >     Exynos5 (Samsung chip on the Arndale and various smartphones and
> >     tablets)
> 
> In the Exynos 5 family we only support Exynos 5250 (Exynos 5 Dual) and
> Exynos 5420 (Exynos Octa).
> 
> Regards,
> 
> -- 
> Julien Grall
>

_______________________________________________
Publicity mailing list
Publicity@xxxxxxxxxxxxxxxxxxxx
http://lists.xenproject.org/cgi-bin/mailman/listinfo/publicity