[PATCH] On Hurd, silently ignore ENOSYS for madvise().

[manolis837]

From: Manolis Ragkousis <manolis...@gmail.com>

madvise() is not implemented on Hurd.
See <https://lists.gnu.org/archive/html/guile-devel/2017-06/msg00001.html>.

* libguile/vm.c (return_unused_stack_to_os): Ignore madvise() related
  ENOSYS on Hurd.
---
 libguile/vm.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libguile/vm.c b/libguile/vm.c
index 18f219249..0daeb5154 100644
--- a/libguile/vm.c
+++ b/libguile/vm.c
@@ -904,8 +904,14 @@ return_unused_stack_to_os (struct scm_vm *vp)
         ret = madvise ((void *) lo, hi - lo, MADV_DONTNEED);
       while (ret && errno == -EAGAIN);
 
+#if defined __gnu_hurd__
+      /* On Hurd ignore ENOSYS, madvise is not supported.*/
+      if (ret && errno != ENOSYS)
+        perror ("madvise failed");
+#else
       if (ret)
         perror ("madvise failed");
+#endif
     }
 
   vp->sp_min_since_gc = vp->sp;
-- 
2.13.0