/usr/src/gcc-4.8/debian/patches/hurd-boehm-gc.diff is in gcc-4.8-source 4.8.5-4ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | Index: b/src/boehm-gc/configure.host
===================================================================
--- a/src/boehm-gc/configure.host
+++ b/src/boehm-gc/configure.host
@@ -41,7 +41,7 @@ else
fi
case "${host}" in
- *-linux*|*-kfreebsd*-gnu*)
+ *-linux*|*-kfreebsd*-gnu*|*-gnu*)
gc_use_mmap=yes
;;
esac
Index: b/src/boehm-gc/include/private/gcconfig.h
===================================================================
--- a/src/boehm-gc/include/private/gcconfig.h
+++ b/src/boehm-gc/include/private/gcconfig.h
@@ -2094,7 +2094,7 @@
# endif
# endif
-#if defined(LINUX) && defined(USE_MMAP)
+#if (defined(LINUX) || defined(HURD)) && defined(USE_MMAP)
/* The kernel may do a somewhat better job merging mappings etc. */
/* with anonymous mappings. */
# define USE_MMAP_ANON
|