Hi, I believe this is breaking bootstrap on aarch64-linux-gnu with kernels <=3.15, 3.16 and above are fine. __kernel_old_{gid,uid}_t were changed in 3.16 from unsigned int to unsigned short. <=3.15 kernel will trigger static asserts in libsanitizer while compiling GCC. I created PR: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64435 (includes all the details). Attaching a patch with resolved issues on F19 + 3.12 kernel (also bootstrapped in QEMU with F21 rootfs + 3.17 kernel) on aarch64-linux-gnu. david