On Wed, May 16, 2018 at 11:29:13AM -0400, Rich Felker wrote: > On Wed, May 16, 2018 at 03:20:47PM +0100, Dave Martin wrote: > > There are constraints on defining AT_* auxvec tags that are not > > obvious to the casual maintainer of either the global > > <uapi/linux/auxvec.h> or the arch-specific headers. This is likely > > to lead to mistakes. (I certainly fell foul of it...) > > > > For the benefit of future maintainers, this patch collects the > > relevant information in one place, documenting how the namespace > > needs to be managed, and noting all the values currently in use. > > > > Maintaining a global list may result in some merge conflicts, but > > AT_* values are not added frequently. I'm open to suggestions on > > the best approach. > > > > I also assume that values 38 and 39 may have been used for > > historical purposes, such as an architecture that is no longer > > supported. If they have definitely never been used for anything, > > they could be removed from the "reserved" list. > > On the userspace side (elf.h) all the AT_* constants are in one file. > Why don't we just do the same here and eliminate the > arch/*/include/uapi/asm/auxvec.h files and likewise the need to > manually maintain consistency of the comments about reservations? > > If there are reasons not to do that, I'm not opposed to this patch > as-is. I agree, it would be better to merge them. My concern was that the correct way to get these definitions from userspace is very unclear, so there may be software out there including <asm/auxvec.h> directly, which would now lack expected definitions. codesearch.debian.net shows no real hits for that, so maybe I'm too paranoid. Since <linux/auxvec.h> only contains #defines, it may be enough for arch <asm/auxvec.h> headers to include <linux/auxvec.h>. Thoughts? Cheers ---Dave
