On 02/07/2016 12:31 PM, Mikko Rapeli wrote: > On Thu, Jan 07, 2016 at 10:30:40AM -0800, Stephen Hemminger wrote: >> On Thu, 7 Jan 2016 07:29:50 +0000 >> Mikko Rapeli <mikko.rapeli@xxxxxx> wrote: >> >>> On Wed, Jan 06, 2016 at 09:20:07AM -0800, Stephen Hemminger wrote: >>>> This commit breaks compilation of iproute2 with net-next. >>> >>> Ok, linux/if.h and libc net/if.h have overlapping defines, and this is not >>> the only one. I saw lots of them in the core dump headers. >>> >>> How should we handle them? Another ifndef for IFNAMSIZ into kernel uapi >>> headers? >>> >>> -Mikko >> >> Probably need to do the same thing that was done previously for these >> kind of conflicts. This makes make linux/if.h change to adapt to net/if.h >> being included before it. > > So uapi headers now have a libc-compat.h > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/libc-compat.h?id=refs/tags/v4.5-rc2 > which tries to detect and fix incompatibilities between Linux kernel and glibc > headers. Part of the fix is then in the kernel side headers and another part > should be in glibc headers, but glibc git repo does not include any of these > fixes yet. > > Has the glibc part of this incompatiblity mess been discussed and agreed > with glibc developers? I don't remember any recent discussions on libc-alpha, or any bug reports about this concrete change. (Redirecting to libc-alpha, which seems the more appropriate list.) > Many of the conflics arise from propably old glibc headers which had copied > out definitions from the Linux kernel side before it could export any headers > to userspace. I assume that the glibc headers are not allowed to depend and > include Linux kernel uapi headers in deployments but maybe the Linux kernel > headers could be used at glibc compile time to generate needed glibc side > definitions. That would allow having a single source for definitions like > FNAMSIZ 16. My impression is that this inconsistency isn't the only problem. The problems start if application developers need functionality which is only in kernel-provided headers, but they still need to include glibc headers at the same time. > I'm drafting a test, similar to the kernel uapi header compile test > https://github.com/mcfrisk/linux/blob/headers_test_v05/scripts/headers_compile_test.sh > for the glibc conflicts too, and of course noticed that also glibc headers > conflict with each other. With some workarounds I can test compile each kernel > uapi header against all compiling glibc headers and see the conflicts as > build failures. That could be helpful. I'm not familiar with relevant developer practices. It seems to me that from an application developer point of view, kernel headers are updated a bit more frequently than glibc headers. This likely pushes the solution into a certain direction (and may be the rationale behind the kernel's libc-compat.h). Florian -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
