diff options
author | Randy Dunlap <randy.dunlap@oracle.com> | 2007-10-17 02:29:29 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-17 11:42:56 -0400 |
commit | 1810732e94576ae0d04e953ecaba8c7151c9a287 (patch) | |
tree | c2ff43ec67ea41d2e5fee33b5e9a0d828871d3b5 /Documentation/filesystems/ramfs-rootfs-initramfs.txt | |
parent | 0e1ccb9619e8e9ae86dfc5a4645ccf3bf5a2eb3f (diff) |
docs: ramdisk/initrd/initramfs corrections
initrd/initramfs/ramdisk docs:
- fix typos/spellos/grammar
- clarify RAM disk config location
- correct cpio option
Acked-by: Bryan O'Sullivan <bos@serpentine.com>
Acked-by: Rob Landley <rob@landley.net>
Cc: Werner Almesberger <werner@almesberger.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/filesystems/ramfs-rootfs-initramfs.txt')
-rw-r--r-- | Documentation/filesystems/ramfs-rootfs-initramfs.txt | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/Documentation/filesystems/ramfs-rootfs-initramfs.txt b/Documentation/filesystems/ramfs-rootfs-initramfs.txt index 25981e2e51be..339c6a4f220e 100644 --- a/Documentation/filesystems/ramfs-rootfs-initramfs.txt +++ b/Documentation/filesystems/ramfs-rootfs-initramfs.txt | |||
@@ -8,7 +8,7 @@ What is ramfs? | |||
8 | 8 | ||
9 | Ramfs is a very simple filesystem that exports Linux's disk caching | 9 | Ramfs is a very simple filesystem that exports Linux's disk caching |
10 | mechanisms (the page cache and dentry cache) as a dynamically resizable | 10 | mechanisms (the page cache and dentry cache) as a dynamically resizable |
11 | ram-based filesystem. | 11 | RAM-based filesystem. |
12 | 12 | ||
13 | Normally all files are cached in memory by Linux. Pages of data read from | 13 | Normally all files are cached in memory by Linux. Pages of data read from |
14 | backing store (usually the block device the filesystem is mounted on) are kept | 14 | backing store (usually the block device the filesystem is mounted on) are kept |
@@ -34,7 +34,7 @@ ramfs and ramdisk: | |||
34 | ------------------ | 34 | ------------------ |
35 | 35 | ||
36 | The older "ram disk" mechanism created a synthetic block device out of | 36 | The older "ram disk" mechanism created a synthetic block device out of |
37 | an area of ram and used it as backing store for a filesystem. This block | 37 | an area of RAM and used it as backing store for a filesystem. This block |
38 | device was of fixed size, so the filesystem mounted on it was of fixed | 38 | device was of fixed size, so the filesystem mounted on it was of fixed |
39 | size. Using a ram disk also required unnecessarily copying memory from the | 39 | size. Using a ram disk also required unnecessarily copying memory from the |
40 | fake block device into the page cache (and copying changes back out), as well | 40 | fake block device into the page cache (and copying changes back out), as well |
@@ -46,8 +46,8 @@ unnecessary work for the CPU, and pollutes the CPU caches. (There are tricks | |||
46 | to avoid this copying by playing with the page tables, but they're unpleasantly | 46 | to avoid this copying by playing with the page tables, but they're unpleasantly |
47 | complicated and turn out to be about as expensive as the copying anyway.) | 47 | complicated and turn out to be about as expensive as the copying anyway.) |
48 | More to the point, all the work ramfs is doing has to happen _anyway_, | 48 | More to the point, all the work ramfs is doing has to happen _anyway_, |
49 | since all file access goes through the page and dentry caches. The ram | 49 | since all file access goes through the page and dentry caches. The RAM |
50 | disk is simply unnecessary, ramfs is internally much simpler. | 50 | disk is simply unnecessary; ramfs is internally much simpler. |
51 | 51 | ||
52 | Another reason ramdisks are semi-obsolete is that the introduction of | 52 | Another reason ramdisks are semi-obsolete is that the introduction of |
53 | loopback devices offered a more flexible and convenient way to create | 53 | loopback devices offered a more flexible and convenient way to create |
@@ -103,7 +103,7 @@ All this differs from the old initrd in several ways: | |||
103 | initramfs archive is a gzipped cpio archive (like tar only simpler, | 103 | initramfs archive is a gzipped cpio archive (like tar only simpler, |
104 | see cpio(1) and Documentation/early-userspace/buffer-format.txt). The | 104 | see cpio(1) and Documentation/early-userspace/buffer-format.txt). The |
105 | kernel's cpio extraction code is not only extremely small, it's also | 105 | kernel's cpio extraction code is not only extremely small, it's also |
106 | __init data that can be discarded during the boot process. | 106 | __init text and data that can be discarded during the boot process. |
107 | 107 | ||
108 | - The program run by the old initrd (which was called /initrd, not /init) did | 108 | - The program run by the old initrd (which was called /initrd, not /init) did |
109 | some setup and then returned to the kernel, while the init program from | 109 | some setup and then returned to the kernel, while the init program from |
@@ -220,7 +220,7 @@ device) but the separate packaging of initrd (which is nice if you have | |||
220 | non-GPL code you'd like to run from initramfs, without conflating it with | 220 | non-GPL code you'd like to run from initramfs, without conflating it with |
221 | the GPL licensed Linux kernel binary). | 221 | the GPL licensed Linux kernel binary). |
222 | 222 | ||
223 | It can also be used to supplement the kernel's built-in initamfs image. The | 223 | It can also be used to supplement the kernel's built-in initramfs image. The |
224 | files in the external archive will overwrite any conflicting files in | 224 | files in the external archive will overwrite any conflicting files in |
225 | the built-in initramfs archive. Some distributors also prefer to customize | 225 | the built-in initramfs archive. Some distributors also prefer to customize |
226 | a single kernel image with task-specific initramfs images, without recompiling. | 226 | a single kernel image with task-specific initramfs images, without recompiling. |
@@ -339,7 +339,7 @@ smooth transition and allowing early boot functionality to gradually move to | |||
339 | The move to early userspace is necessary because finding and mounting the real | 339 | The move to early userspace is necessary because finding and mounting the real |
340 | root device is complex. Root partitions can span multiple devices (raid or | 340 | root device is complex. Root partitions can span multiple devices (raid or |
341 | separate journal). They can be out on the network (requiring dhcp, setting a | 341 | separate journal). They can be out on the network (requiring dhcp, setting a |
342 | specific mac address, logging into a server, etc). They can live on removable | 342 | specific MAC address, logging into a server, etc). They can live on removable |
343 | media, with dynamically allocated major/minor numbers and persistent naming | 343 | media, with dynamically allocated major/minor numbers and persistent naming |
344 | issues requiring a full udev implementation to sort out. They can be | 344 | issues requiring a full udev implementation to sort out. They can be |
345 | compressed, encrypted, copy-on-write, loopback mounted, strangely partitioned, | 345 | compressed, encrypted, copy-on-write, loopback mounted, strangely partitioned, |