From: James Hogan <james.hogan@xxxxxxxxxx> Date: Mon, 17 Dec 2012 09:51:04 +0000 > On 10/12/12 12:55, Geert Uytterhoeven wrote: >> On Mon, Dec 10, 2012 at 11:22 AM, James Hogan <james.hogan@xxxxxxxxxx> wrote: >>> On 08/12/12 03:43, H. Peter Anvin wrote: >>>> On 12/05/2012 08:08 AM, James Hogan wrote: >>>>> On 64 bit architectures with no efficient unaligned access, taskstats >>>>> has to add some padding to a reply to prevent unaligned access warnings. >>>>> However this also needs to apply to 32 bit architectures with 64 bit >>>>> struct alignment such as metag (which has 64 bit memory accesses). >>>> >>>> Wait... 64-bit struct alignment on structures with only 32-bit members? >>>> That might be... interesting... in a number of places... >>> >>> I'll rewrite the description as it's a bit misleading. On metag 64bit >>> struct alignment is required when it contains 64bit members, not if it >>> only contains 32bit members. Although metag is a 32bit arch, it can do >>> 64bit memory accesses which must be aligned. >> >> The C alignment rules should take care of this automatically (struct alignment >> is the maximum alignment of its members). > > Hi Geert, > > Please see the comment in mk_reply in kernel/taskstats.c. The structure > is being serialised after 2 NLA headers and a pid which is why the extra > padding needs to be added manually. Please solve netlink attribute 64-bit alignment issues fundamentally rather on a case-by-case basis. We were just discussing this very issue on the netdev list recently, CC:'d -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
