[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC V2] xen: interface: introduce pvclk interface
On Thu, 2016-01-21 at 16:59 +0800, Peng Fan wrote: >Â > To platform device of ARM, hypervisor is responsible for the mapping > between machine address and guest physical address, also responsible > for the irq mapping. > > But to embedded ARM SoC, the hardware clk IP is handled in Dom0. Arguably Xen ought to be the one to do this, but we have determined (rightly, I think) that doing so for the entirely clk tree of an SoC would involve importing an unmanageable amount of code into Xen[0]. In the meantime we defer this to Dom0. I wonder though if it would be possible to manage the clocks for a passthrough device from the toolstack, i.e. is there a sysfs node where one can say "keep the clock for this device enabled (at xMhz) even though you think the device is unused"? If so (or if it can be easily added) then the toolstack would just need to manage that value as part of the passthrough process rather than having the frontend do it via a PV protocol. Ian. [0] I'd like at some point for Xen to gain sufficient knowledge of clock IP to minimally control things like the CPU and DRAM clocks etc, but that needn't imply full clock tree support and would hopefully be a manageable amount of code, which would (hopefully) mostly be about trapping and emulating writes to one or two clock controllers per platform and arbitrating a small set of bits (while allowing dom0 to control the others). This is at least a medium if not long term idea though, and for all I know it might turn out to be unworkable in practice. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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