On Fri, 2015-04-03 at 14:39 +0200, Julien Grall wrote: > > On 02/04/2015 18:19, Ian Campbell wrote: > > On Thu, 2015-04-02 at 17:01 +0100, Ian Campbell wrote: > >> On Thu, 2015-04-02 at 16:50 +0100, Ian Campbell wrote: > >> > >>> Writing to the bottom half (e.g. w0) of a register implicitly clears the > >>> top half, IIRC, so I think a kernel is unlikely to want to do this, even > >>> if it could (which I'm not quite convinced of). > >> > >> That said, I'll see if I can make something work with the handle_* > >> taking the reg number instead of a pointer and calling select_user_reg > >> in each. > > > > Actually don't even need that, I think the following does what is > > needed. I'm not 100% convinced it is needed though, but it's simple > > enough, and I can't find anything in the ARM ARM right now which rules > > out what you are suggesting, even if it is unlikely. > > The paragraph "Pseudocode description of registers in AArch64 state" in > section B1.2.1 (ARMv8 DDI0487 A.d) confirms your previous mail. I.e > "writing to the bottom half (e.g. w0) of a register implicitly clears > the top half". > > I think it may be worth to mention the paragraph somewhere in the patch.
Yes, I shall, in the commit log most likely. Ian. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel