Bug #304
Updated by Linus Lüssing over 7 years ago
On a Debian Sid compiling for a 4.9-rc3 kernel with gcc 6.2.0-10, kernel, I curently get the following error: <pre> root@Linus-Debian:/mnt/batman-adv-t_x# make /mnt/batman-adv-t_x/gen-compat-autoconf.sh /mnt/batman-adv-t_x/compat-autoconf.h mkdir -p /mnt/batman-adv-t_x/build/net/batman-adv/ compat-patches/replacements.sh touch /mnt/batman-adv-t_x/build/net/batman-adv/.compat-prepared make -C /lib/modules/4.9.0-rc3+/build M=/mnt/batman-adv-t_x PWD=/mnt/batman-adv-t_x REVISION=2016.4 CONFIG_BATMAN_ADV=m CONFIG_BATMAN_ADV_DEBUG=n CONFIG_BATMAN_ADV_DEBUGFS=y CONFIG_BATMAN_ADV_BLA=y CONFIG_BATMAN_ADV_DAT=y CONFIG_BATMAN_ADV_NC=n CONFIG_BATMAN_ADV_MCAST=y CONFIG_BATMAN_ADV_BATMAN_V=n INSTALL_MOD_DIR=updates/ modules make[1]: Entering directory '/usr/src/linux-headers-4.9.0-rc3+' cat: -: No such file or directory CC [M] /mnt/batman-adv-t_x/build/net/batman-adv/../../../compat-sources/net/core/skbuff.o /mnt/batman-adv-t_x/build/net/batman-adv/../../../compat-sources/net/core/skbuff.c:1:0: error: code model kernel does not support PIC mode /* scripts/Makefile.build:290: recipe for target '/mnt/batman-adv-t_x/build/net/batman-adv/../../../compat-sources/net/core/skbuff.o' failed make[3]: *** [/mnt/batman-adv-t_x/build/net/batman-adv/../../../compat-sources/net/core/skbuff.o] Error 1 scripts/Makefile.build:475: recipe for target '/mnt/batman-adv-t_x/build/net/batman-adv' failed make[2]: *** [/mnt/batman-adv-t_x/build/net/batman-adv] Error 2 Makefile:1482: recipe for target '_module_/mnt/batman-adv-t_x' failed make[1]: *** [_module_/mnt/batman-adv-t_x] Error 2 make[1]: Leaving directory '/usr/src/linux-headers-4.9.0-rc3+' Makefile:89: recipe for target 'all' failed make: *** [all] Error 2 </pre> It seems to have something to do with PIE hardening which got enabled by default in gcc6 last week in Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=835148 Compiling with '$ make EXTRA_CFLAGS="-fno-pie"' helps. So my question is, whether this flag should be added to the batman-adv out-of-tree Makefile. Some comments seem to suggest, that PIE does not work for kernels / kernel modules by design. (I have not looked at what PIE hardening actually is, so I have no clue yet whether disabling is the right choice)