[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2 7/7] xen/arm: set the system time in Xen via the XENPF_settime64 hypercall
On Tue, 10 Nov 2015, Arnd Bergmann wrote: > On Tuesday 10 November 2015 11:57:55 Stefano Stabellini wrote: > > + op.u.settime64.nsecs = now.tv_nsec; > > + op.u.settime64.system_time = arch_timer_read_counter() * > > (u64)NSEC_PER_SEC; > > + do_div(op.u.settime64.system_time, arch_timer_get_rate()); > > NSEC_PER_SEC is a large number, doesn't that multiplication overflow the > 64-bit system_time variable? It could be a concern, you are right. I think I can solve this issue and remove multiple do_divs by calculating nsec_per_tick at initialization time and use it here and in xen_read_wallclock. > > + printk("GTOD: Setting to %llu.%u at %llu\n", > > %llu.%09u > > so you get the leading zeroes. > > > + op.u.settime64.secs, > > + op.u.settime64.nsecs, > > + op.u.settime64.system_time); > > + (void)HYPERVISOR_platform_op(&op); > > Arnd > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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