From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Mon, 09 Nov 2015 21:45:50 +0100 Subject: [PATCH 3/3] xen/arm: set the system time in Xen via the XENPF_settime hypercall In-Reply-To: References: Message-ID: <5034618.DZpKjPX0Jn@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Monday 09 November 2015 17:42:50 Stefano Stabellini wrote: > On Mon, 9 Nov 2015, Stefano Stabellini wrote: > > On Mon, 9 Nov 2015, Arnd Bergmann wrote: > > > On Monday 09 November 2015 14:10:22 Stefano Stabellini wrote: > > > > > > Just to make sure that this is actually the correct interface > > > that you want to call: > > > > > > __current_kernel_time{,64}() is the fastest interface we have > > > to get an approximation of the current time, while ignoring > > > all of the locking. > > > > > > Is is possible that you instead want ktime_get_real_ts64(), > > > which gives you the time as precise as the kernel knows it, > > > but uses locking? > > > > I am not 100% sure. Can I call ktime_get_real_ts64 from a > > pvclock_gtod notifier_call function? > > It doesn't look like it: we would be getting the tk_core seqcount twice. Ok, I see. I'm still unsure what this is all good for, but at least this call appears to be safe. Arnd