Handle kernel/FUSE disagreement over Linux attrs

[bup.git] / Documentation / bup-index.md

diff --git a/Documentation/bup-index.md b/Documentation/bup-index.md
index 003548f53871346f8b45f846441d883d508ad1e0..280d9eb1d4fe361fc124eb07fceda9573c9f3f4c 100644 (file)
--- a/Documentation/bup-index.md
+++ b/Documentation/bup-index.md
@@ -42,6 +42,15 @@ need the same information).
 
 # NOTES
 
+At the moment, bup will ignore Linux attributes (cf. chattr(1) and
+lsattr(1)) on some systems (any big-endian systems where sizeof(long)
+< sizeof(int)).  This is because the Linux kernel and FUSE currently
+disagree over the type of the attr system call arguments, and so on
+big-endian systems there's no way to get the results without the risk
+of stack corruption (http://lwn.net/Articles/575846/).  In these
+situations, bup will print a warning the first time Linux attrs are
+relevant during any index/save/restore operation.
+
 bup makes accommodations for the expected "worst-case" filesystem
 timestamp resolution -- currently one second; examples include VFAT,
 ext2, ext3, small ext4, etc.  Since bup cannot know the filesystem
@@ -148,12 +157,11 @@ does, due to the accommodations described above.
     `$BUP_DIR/bupindex`.
 
 \--exclude=*path*
-:   exclude *path* from the backup; bup will not expand *path* in any
-    way (may be repeated).
+:   exclude *path* from the backup (may be repeated).
 
 \--exclude-from=*filename*
 :   read --exclude paths from *filename*, one path per-line (may be
-    repeated).
+    repeated).  Ignore completely empty lines.
 
 \--exclude-rx=*pattern*
 :   exclude any path matching *pattern*, which must be a Python regular
@@ -172,7 +180,7 @@ does, due to the accommodations described above.
 
 \--exclude-rx-from=*filename*
 :   read --exclude-rx patterns from *filename*, one pattern per-line
-    (may be repeated).
+    (may be repeated).  Ignore completely empty lines.
 
 \--no-check-device
 :   don't mark a an entry invalid if the device number (stat(2)
@@ -185,8 +193,7 @@ does, due to the accommodations described above.
     is updated; with two `-v`, print each file too.
 
 
-# EXAMPLE
-
+# EXAMPLES
     bup index -vux /etc /var /usr