--- /dev/null
+From 3341e204dc1e1da6ecbc1ffbe59fca33f23ca557 Mon Sep 17 00:00:00 2001
+From: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+Date: Tue, 28 Jul 2020 12:31:31 +0200
+Subject: [PATCH] syscall: don't fail if __NR_signalfd is not defined
+
+lxc fails to build if __NR_signalfd is not defined since version 4.0.0
+and
+https://github.com/lxc/lxc/commit/bed09c9cc0bec7bbd2442fcce4a2a0f03994cb09
+
+However, some architectures don't define __NR_signalfd but only
+__NR_signalfd4. This is the case for example for nios2 or csky:
+https://github.com/bminor/glibc/blob/f9ac84f92f151e07586c55e14ed628d493a5929d/sysdeps/unix/sysv/linux/nios2/arch-syscall.h
+https://github.com/bminor/glibc/blob/f9ac84f92f151e07586c55e14ed628d493a5929d/sysdeps/unix/sysv/linux/csky/arch-syscall.h
+
+Fixes:
+ - http://autobuild.buildroot.org/results/75096a48d2dbda57459523db3ed0952e63f93535
+
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+[Retrieved from:
+https://github.com/lxc/lxc/commit/3341e204dc1e1da6ecbc1ffbe59fca33f23ca557]
+---
+ src/lxc/syscall_numbers.h | 3 ---
+ src/lxc/syscall_wrappers.h | 2 ++
+ 2 files changed, 2 insertions(+), 3 deletions(-)
+
+diff --git a/src/lxc/syscall_numbers.h b/src/lxc/syscall_numbers.h
+index e2e7883786..72e4ffe460 100644
+--- a/src/lxc/syscall_numbers.h
++++ b/src/lxc/syscall_numbers.h
+@@ -228,9 +228,6 @@
+ #if _MIPS_SIM == _MIPS_SIM_ABI64 /* n64 */
+ #define __NR_signalfd 5276
+ #endif
+- #else
+- #define -1
+- #warning "__NR_signalfd not defined for your architecture"
+ #endif
+ #endif
+
+diff --git a/src/lxc/syscall_wrappers.h b/src/lxc/syscall_wrappers.h
+index 220ef65fde..6aaa437226 100644
+--- a/src/lxc/syscall_wrappers.h
++++ b/src/lxc/syscall_wrappers.h
+@@ -112,8 +112,10 @@ static inline int signalfd(int fd, const sigset_t *mask, int flags)
+ int retval;
+
+ retval = syscall(__NR_signalfd4, fd, mask, _NSIG / 8, flags);
++#ifdef __NR_signalfd
+ if (errno == ENOSYS && flags == 0)
+ retval = syscall(__NR_signalfd, fd, mask, _NSIG / 8);
++#endif
+
+ return retval;
+ }