diff options
| author | kamil <kamil@NetBSD.org> | 2018-05-30 17:48:13 +0000 |
|---|---|---|
| committer | kamil <kamil@NetBSD.org> | 2018-05-30 17:48:13 +0000 |
| commit | 9128e3119d85146df2a0960362103d312b5f72ae (patch) | |
| tree | b12d087b7ba43b5d89c3fe54d7cae9e5a8f4626c /tests/kernel | |
| parent | ca6ad33a9855119a058a070fb46daeaeb6f91155 (diff) | |
Add a comment for the workaround in trigger_bus()
Explain PROT_READ|PROT_WRITE.
Diffstat (limited to 'tests/kernel')
| -rw-r--r-- | tests/kernel/h_segv.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/tests/kernel/h_segv.c b/tests/kernel/h_segv.c index 44a7efec637..c34208beb4a 100644 --- a/tests/kernel/h_segv.c +++ b/tests/kernel/h_segv.c @@ -1,4 +1,4 @@ -/* $NetBSD: h_segv.c,v 1.6 2018/05/30 17:31:34 kamil Exp $ */ +/* $NetBSD: h_segv.c,v 1.7 2018/05/30 17:48:13 kamil Exp $ */ /*- * Copyright (c) 2017 The NetBSD Foundation, Inc. @@ -29,7 +29,7 @@ * POSSIBILITY OF SUCH DAMAGE. */ #include <sys/cdefs.h> -__RCSID("$NetBSD: h_segv.c,v 1.6 2018/05/30 17:31:34 kamil Exp $"); +__RCSID("$NetBSD: h_segv.c,v 1.7 2018/05/30 17:48:13 kamil Exp $"); #include <sys/types.h> #include <sys/mman.h> @@ -119,7 +119,12 @@ trigger_bus(void) if (fp == NULL) err(EXIT_FAILURE, "tmpfile"); - /* Map an empty file with mmap(2) to a pointer. */ + /* + * Map an empty file with mmap(2) to a pointer. + * + * PROT_READ handles read-modify-write sequences emitted for + * certain combinations of CPUs and compilers (e.g. Alpha AXP). + */ p = mmap(0, 1, PROT_READ|PROT_WRITE, MAP_PRIVATE, fileno(fp), 0); if (p == MAP_FAILED) err(EXIT_FAILURE, "mmap"); |
