Date: Mon, 5 Oct 2015 21:44:26 -0400 From: Rich Felker <dalias@...ifal.cx> To: Rob Landley <rob@...dley.net> Cc: Denys Vlasenko <vda.linux@...glemail.com>, Aboriginal Linux <aboriginal@...ts.landley.net>, musl@...ts.openwall.com Subject: musl and kernel headers [was Re: system-images 1.4.2: od is broken; bzip2 is missing] On Mon, Oct 05, 2015 at 10:08:10AM -0500, Rob Landley wrote: > > Re musl: two cases of breakage: > > > > #include <netinet/in.h> > > #include <linux/if_bridge.h> > > results in: > > In file included from /usr/include/linux/if_bridge.h:18, > > from networking/brctl.c:67: > > /usr/include/linux/in6.h:32: error: redefinition of 'struct in6_addr' > > /usr/include/linux/in6.h:49: error: redefinition of 'struct sockaddr_in6' > > /usr/include/linux/in6.h:59: error: redefinition of 'struct ipv6_mreq' > > > > and > > > > #include <linux/ethtool.h> > > #include <net/ethernet.h> > > results in: > > In file included from /usr/include/net/ethernet.h:10, > > from networking/ifplugd.c:41: > > /usr/include/netinet/if_ether.h:96: error: redefinition of 'struct ethhdr' > > > > That I leave to Rich. :) Including kernel headers is just really problematic. These days they try to make it work on glibc with a complex dance between glibc's headers and the kernel headers. You're likely to have the best luck by including the libc headers first. I think Sabotage and possibly some other musl-based dists are patching the kernel headers to make them behave better; see: https://github.com/sabotage-linux/sabotage/blob/master/pkg/kernel-headers But it might be possible that we can just #define whatever macro the kernel headers expect to suppress redefinitions, if it's in a reserved namespace. This would only fix the case where the kernel headers are included _after_ the libc/userspace ones, but it's not too ugly. I probably won't get around to it myself but if anyone wants to check what macros we'd need to define (and where), let's discuss it (cc'ing musl list). The cleaner approach is just avoiding including both the kernel headers and libc/userspace headers for the same things in the same file. In theory this may be hard in some cases, but I find that I can almost always fix these sorts of errors during a build by commenting out one or two #include lines. Rich
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