From: Andi Drebes <lists-receive@programmierforen.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org, Karel Zak <kzak@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>,
Phillip Lougher <phillip@lougher.demon.co.uk>
Subject: [PATCH 2/2] Update documentation
Date: Tue, 4 Dec 2007 13:02:32 +0100 [thread overview]
Message-ID: <200712041302.33202.lists-receive@programmierforen.de> (raw)
In-Reply-To: <200712041259.52118.lists-receive@programmierforen.de>
The following patch updates the cramfs documentation according to the changes in PATCH 1/2.
The changes were tested on the following types of machines:
An i386 compatible box (little endian)
UltraSparc IIi (big endian)
Signed-off-by: Andi Drebes <andi@programmierforen.de>
---
README | 19 +++++--------------
1 file changed, 5 insertions(+), 14 deletions(-)
diff --git a/fs/cramfs/README b/fs/cramfs/README
index 445d1c2..91efe77 100644
--- a/fs/cramfs/README
+++ b/fs/cramfs/README
@@ -6,8 +6,11 @@ a bit looser, e.g. it doesn't care if the <file_data> items are
swapped around (though it does care that directory entries (inodes) in
a given directory are contiguous, as this is used by readdir).
-All data is currently in host-endian format; neither mkcramfs nor the
-kernel ever do swabbing. (See section `Block Size' below.)
+All data is now in little endian format. Before, it was in host endian
+format. In order to make filesystem images more shareable between machines
+with a different byte order, cramfs' specification ("this README file")
+was updated. There will be no support for big endian filesystems in the
+future.
<filesystem>:
<superblock>
@@ -108,18 +111,6 @@ kernels, not even necessarily kernels of the same architecture if
PAGE_CACHE_SIZE is subject to change between kernel versions
(currently possible with arm and ia64).
-The remaining options try to make cramfs more sharable.
-
-One part of that is addressing endianness. The two options here are
-`always use little-endian' (like ext2fs) or `writer chooses
-endianness; kernel adapts at runtime'. Little-endian wins because of
-code simplicity and little CPU overhead even on big-endian machines.
-
-The cost of swabbing is changing the code to use the le32_to_cpu
-etc. macros as used by ext2fs. We don't need to swab the compressed
-data, only the superblock, inodes and block pointers.
-
-
The other part of making cramfs more sharable is choosing a block
size. The options are:
prev parent reply other threads:[~2007-12-04 12:02 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-04 11:59 [PATCH 0/2] Make cramfs little endian only Andi Drebes
2007-12-04 12:01 ` [PATCH 1/2] " Andi Drebes
2007-12-04 15:34 ` Jörn Engel
2007-12-04 20:37 ` Andi Drebes
2007-12-04 20:58 ` Linus Torvalds
2007-12-04 21:31 ` Andi Drebes
2007-12-04 22:35 ` Linus Torvalds
2007-12-04 22:58 ` Jeff Garzik
2007-12-05 21:57 ` Andi Drebes
2007-12-05 22:21 ` Linus Torvalds
2007-12-05 22:41 ` Jörn Engel
2007-12-06 16:38 ` Andi Drebes
2007-12-06 16:27 ` Andi Drebes
2007-12-06 16:47 ` Jörn Engel
2007-12-06 17:35 ` Linus Torvalds
2007-12-06 17:31 ` Linus Torvalds
2007-12-06 22:37 ` Andi Drebes
2007-12-04 20:11 ` Andrew Morton
2007-12-04 20:58 ` Andi Drebes
2007-12-04 12:02 ` Andi Drebes [this message]
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