patch-2.1.107 linux/Documentation/ramdisk.txt

• Lines: 230
• Date: Wed Jun 24 14:30:07 1998
• Orig file: v2.1.106/linux/Documentation/ramdisk.txt
• Orig date: Sat May 2 14:19:52 1998

diff -u --recursive --new-file v2.1.106/linux/Documentation/ramdisk.txt linux/Documentation/ramdisk.txt
@@ -1,4 +1,3 @@
-
 Using the RAM disk block device with Linux
 ------------------------------------------
 
@@ -7,20 +6,20 @@
 	1) Overview
 	2) Kernel Command Line Parameters
 	3) Using "rdev -r" With New Kernels
-	4) An Example of Creating a Compressed ramdisk 
+	4) An Example of Creating a Compressed RAM Disk 
 
 
 1) Overview
 -----------
 
-As of kernel v1.3.48, the ramdisk driver was substantially changed.
+As of kernel v1.3.48, the RAM disk driver was substantially changed.
 
 The older versions would grab a chunk of memory off the top before
 handing the remainder to the kernel at boot time. Thus a size parameter
 had to be specified via "ramdisk=1440" or "rdev -r /dev/fd0 1440" so
 that the driver knew how much memory to grab.
 
-Now the ramdisk dynamically grows as more space is required. It does
+Now the RAM disk dynamically grows as more space is required. It does
 this by using RAM from the buffer cache. The driver marks the buffers
 it is using with a new "BH_Protected" flag so that the kernel does 
 not try to reuse them later. This means that the old size parameter
@@ -28,9 +27,9 @@
 of the "rdev -r" or "ramsize" (usually a symbolic link to "rdev")
 command has changed.
 
-Also, the new ramdisk supports up to 16 ramdisks out of the box, and can
-be reconfigured in rd.c to support up to 255 ramdisks.  To use multiple
-ramdisk support with your system, run 'mknod /dev/ramX b 1 X' and chmod
+Also, the new RAM disk supports up to 16 RAM disks out of the box, and can
+be reconfigured in rd.c to support up to 255 RAM disks.  To use multiple
+RAM disk support with your system, run 'mknod /dev/ramX b 1 X' and chmod
 (to change its permissions) it to your liking.  The default /dev/ram(disk)
 uses minor #1, so start with ram2 and go from there.
 
@@ -38,14 +37,14 @@
 to make it clearer.  The original "ramdisk=<ram_size>" has been kept around
 for compatibility reasons, but it will probably be removed in 2.1.x.
 
-The new ramdisk also has the ability to load compressed ramdisk images,
+The new RAM disk also has the ability to load compressed RAM disk images,
 allowing one to squeeze more programs onto an average installation or 
 rescue floppy disk.
 
 Notes: You may have "/dev/ram" or "/dev/ramdisk" or both. They are
-equivalent from the standpoint of this document. Also, the new ramdisk
+equivalent from the standpoint of this document. Also, the new RAM disk
 is a config option. When running "make config", make sure you enable
-ramdisk support for the kernel you intend to use the ramdisk with.
+RAM disk support for the kernel with which you intend to use the RAM disk.
 
 
 2) Kernel Command Line Parameters
@@ -55,42 +54,42 @@
 	=================
 
 To allow a kernel image to reside on a floppy disk along with a compressed
-ramdisk image, the "ramdisk_start=<offset>" command was added. The kernel
-can't be included into the compressed ramdisk filesystem image, because
+RAM disk image, the "ramdisk_start=<offset>" command was added. The kernel
+can't be included into the compressed RAM disk filesystem image, because
 it needs to be stored starting at block zero so that the BIOS can load the 
-bootsector and then the kernel can bootstrap itself to get going.
+boot sector and then the kernel can bootstrap itself to get going.
 
-Note: If you are using an uncompressed ramdisk image, then the kernel can
-be a part of the filesystem image that is being loaded into the ramdisk,
+Note: If you are using an uncompressed RAM disk image, then the kernel can
+be a part of the filesystem image that is being loaded into the RAM disk,
 and the floppy can be booted with LILO, or the two can be separate as
 is done for the compressed images.
 
-If you are using a two-disk boot/root setup (kernel on #1, ramdisk image
-on #2) then the ramdisk would start at block zero, and an offset of
+If you are using a two-disk boot/root setup (kernel on #1, RAM disk image
+on #2) then the RAM disk would start at block zero, and an offset of
 zero would be used. Since this is the default value, you would not need
 to actually use the command at all.
 
-If instead, you have a "zImage" of about 350k, and a "fs_image.gz" of
-say about 1MB, and you want them both on the same disk, then you
+If instead, you have a "zImage" of about 350 kB, and a "fs_image.gz" of
+say about 1 MB, and you want them both on the same disk, then you
 would use an offset. If you stored the "fs_image.gz" onto the floppy
-starting at an offset of 400kB, you would use "ramdisk_start=400".
+starting at an offset of 400 kB, you would use "ramdisk_start=400".
 
 
 	load_ramdisk=N
 	==============
 
 This parameter tells the kernel whether it is to try to load a
-ramdisk image or not. Specifying "load_ramdisk=1" will tell the
-kernel to load a floppy into the ramdisk. The default value is
-zero, meaning that the kernel should not try to load a ramdisk.
+RAM disk image or not. Specifying "load_ramdisk=1" will tell the
+kernel to load a floppy into the RAM disk. The default value is
+zero, meaning that the kernel should not try to load a RAM disk.
 
 
 	prompt_ramdisk=N
 	================
 
 This parameter tells the kernel whether or not to give you a prompt
-asking you to insert the floppy containing the ramdisk image. In
-a single floppy configuration the ramdisk image is on the same floppy
+asking you to insert the floppy containing the RAM disk image. In
+a single floppy configuration the RAM disk image is on the same floppy
 as the kernel that just finished loading/booting and so a prompt
 is not needed. In this case one can use "prompt_ramdisk=0". In a
 two floppy configuration, you will need the chance to switch disks,
@@ -100,18 +99,18 @@
 	ramdisk_size=N
 	==============
 
-This parameter tells the ramdisk driver to set up ramdisks of Nk size.  The
-default is 4096 (4MB). 
+This parameter tells the RAM disk driver to set up RAM disks of N k size.  The
+default is 4096 (4 MB). 
 
 3) Using "rdev -r" With New Kernels
 -----------------------------------
 
 The usage of the word (two bytes) that "rdev -r" sets in the kernel image
-has changed. The low 11 bits (0 -> 10) specify an offset (in 1k blocks) 
-of up to 2MB (2^11) of where to find the ramdisk (this used to be the 
-size). Bit 14 indicates that a ramdisk is to be loaded, and bit 15
+has changed. The low 11 bits (0 -> 10) specify an offset (in 1 k blocks) 
+of up to 2 MB (2^11) of where to find the RAM disk (this used to be the 
+size). Bit 14 indicates that a RAM disk is to be loaded, and bit 15
 indicates whether a prompt/wait sequence is to be given before trying
-to read the ramdisk. Since the ramdisk dynamically grows as data is
+to read the RAM disk. Since the RAM disk dynamically grows as data is
 being written into it, a size field is no longer required. Bits 11
 to 13 are not currently used and may as well be zero. These numbers
 are no magical secrets, as seen below:
@@ -121,13 +120,13 @@
 ./arch/i386/kernel/setup.c:#define RAMDISK_LOAD_FLAG            0x4000
 
 Consider a typical two floppy disk setup, where you will have the 
-kernel on disk one, and have already put a ramdisk image onto disk #2.
+kernel on disk one, and have already put a RAM disk image onto disk #2.
 
-Hence you want to set bits 0 to 13 as zero, meaning that your ramdisk
-starts at an offset of zero kB from the beginning of the floppy.
+Hence you want to set bits 0 to 13 as 0, meaning that your RAM disk
+starts at an offset of 0 kB from the beginning of the floppy.
 The command line equivalent is: "ramdisk_start=0"
 
-You want bit 14 as one, indicating that a ramdisk is to be loaded.
+You want bit 14 as one, indicating that a RAM disk is to be loaded.
 The command line equivalent is: "load_ramdisk=1"
 
 You want bit 15 as one, indicating that you want a prompt/keypress
@@ -147,20 +146,20 @@
 	append = "load_ramdisk=1"
 
 
-4) An Example of Creating a Compressed ramdisk 
+4) An Example of Creating a Compressed RAM Disk 
 ----------------------------------------------
 
-To create a ramdisk image, you will need a spare block device to
-construct it on. This can be the ramdisk device itself, or an
+To create a RAM disk image, you will need a spare block device to
+construct it on. This can be the RAM disk device itself, or an
 unused disk partition (such as an unmounted swap partition). For this 
-example, we will use the ramdisk device, "/dev/ram".
+example, we will use the RAM disk device, "/dev/ram".
 
-Note: This technique should not be done on a machine with less than 8MB
+Note: This technique should not be done on a machine with less than 8 MB
 of RAM. If using a spare disk partition instead of /dev/ram, then this
 restriction does not apply.
 
-a) Decide on the ramdisk size that you want. Say 2MB for this example.
-   Create it by writing to the ramdisk device. (This step is not currently
+a) Decide on the RAM disk size that you want. Say 2 MB for this example.
+   Create it by writing to the RAM disk device. (This step is not currently
    required, but may be in the future.) It is wise to zero out the
    area (esp. for disks) so that maximal compression is achieved for
    the unused blocks of the image that you are about to create.
@@ -174,9 +173,9 @@
 c) Mount it, copy the files you want to it (eg: /etc/* /dev/* ...)
    and unmount it again.
 
-d) Compress the contents of the ramdisk. The level of compression
+d) Compress the contents of the RAM disk. The level of compression
    will be approximately 50% of the space used by the files. Unused
-   space on the ramdisk will compress to almost nothing.
+   space on the RAM disk will compress to almost nothing.
 
 	dd if=/dev/ram bs=1k count=2048 | gzip -v9 > /tmp/ram_image.gz
 
@@ -184,23 +183,23 @@
 
 	dd if=zImage of=/dev/fd0 bs=1k
 
-f) Put the ramdisk image onto the floppy, after the kernel. Use an offset
+f) Put the RAM disk image onto the floppy, after the kernel. Use an offset
    that is slightly larger than the kernel, so that you can put another
    (possibly larger) kernel onto the same floppy later without overlapping
-   the ramdisk image. An offset of 400kB for kernels about 350kB in
+   the RAM disk image. An offset of 400 kB for kernels about 350 kB in
    size would be reasonable. Make sure offset+size of ram_image.gz is
-   not larger than the total space on your floppy (usually 1440kB).
+   not larger than the total space on your floppy (usually 1440 kB).
 
 	dd if=/tmp/ram_image.gz of=/dev/fd0 bs=1k seek=400
 
-g) Use "rdev" to set the boot device, ramdisk offset, prompt flag, etc.
+g) Use "rdev" to set the boot device, RAM disk offset, prompt flag, etc.
    For prompt_ramdisk=1, load_ramdisk=1, ramdisk_start=400, one would
    have 2^15 + 2^14 + 400 = 49552.
 
 	rdev /dev/fd0 /dev/fd0
 	rdev -r /dev/fd0 49552
 
-That is it. You now have your boot/root compressed ramdisk floppy. Some
+That is it. You now have your boot/root compressed RAM disk floppy. Some
 users may wish to combine steps (d) and (f) by using a pipe.
 
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