On Thu, Oct 17, 2013 at 04:43:59PM +0530, Anup Patel wrote: > On Thu, Oct 17, 2013 at 2:07 PM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: > > On 16/10/13 18:02, Anup Patel wrote: > >> The PSCI SYSTEM_OFF and SYSTEM_RESET functions are VM or Guest level > >> functions hence cannot be emulated by the in-kernel PSCI emulation code. > > > > Why can't we implement system-wide functionality in the kernel? I fail > > to see the issue here. > > > >> To tackle this, we forward PSCI SYSTEM_OFF and SYSTEM_RESET function > >> calls from Guest to user space (i.e. QEMU or KVMTOOL) via KVM run > >> structure with KVM_EXIT_PSCI exit reason. > > > > I'm really not keen on this approach. Having part of the PSCI > > implementation offloaded to userspace means we don't have a complete > > implementation in KVM anymore, and we end-up duplicating functionality > > all over the place. > > > > Also, OFF and RESET are not PSCI specific concepts, and could be > > implemented in various ways. I'm more inclined to return a > > *standardized* exit code that the various platforms can interpret. > > Please refer to the documentation of SYSTEM_OFF and SYSTEM_RESET > functions in the PSCI specifications. > (More preciesly section 5.10 and 5.11 of > http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0022b/index.html) > Anup, I think everyone knows where to find the specs, and I'm even more sure that Marc knows the details of PSCI. If there is a certain aspect of the spec that you find helpful to this discussion that supports an implementation or design decision, I suggest you try more carefully to explain why you think it is the right solution, possibly using references to the specs in order to help people out. -Christoffer _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
