ramdiskadm(1m) [opensolaris man page]
ramdiskadm(1M) System Administration Commands ramdiskadm(1M) NAME
ramdiskadm - administer ramdisk pseudo device SYNOPSIS
/usr/sbin/ramdiskadm -a name size [g | m | k | b] /usr/sbin/ramdiskadm -d name /usr/sbin/ramdiskadm DESCRIPTION
The ramdiskadm command administers ramdisk(7D), the ramdisk driver. Use ramdiskadm to create a new named ramdisk device, delete an existing named ramdisk, or list information about existing ramdisks. Ramdisks created using ramdiskadm are not persistent across reboots. OPTIONS
The following options are supported: -a name size Create a ramdisk named name of size size and its corresponding block and character device nodes. name must be composed only of the characters a-z, A-Z, 0-9, _ (underbar), and - (hyphen), but it must not begin with a hyphen. It must be no more than 32 characters long. Ramdisk names must be unique. The size can be a decimal number, or, when prefixed with 0x, a hexadecimal number, and can specify the size in bytes (no suffix), 512-byte blocks (suffix b), kilobytes (suffix k), megabytes (suffix m) or gigabytes (suffix g). The size of the ramdisk actually created might be larger than that specified, depending on the hardware implementation. If the named ramdisk is successfully created, its block device path is printed on standard out. -d name Delete an existing ramdisk of the name name. This command succeeds only when the named ramdisk is not open. The associated memory is freed and the device nodes are removed. You can delete only ramdisks created using ramdiskadm. It is not possible to delete a ramdisk that was created during the boot process. Without options, ramdiskadm lists any existing ramdisks, their sizes (in decimal), and whether they can be removed by ramdiskadm (see the description of the -d option, above). EXAMPLES
Example 1 Creating a 2MB Ramdisk Named mydisk # ramdiskadm -a mydisk 2m /dev/ramdisk/mydisk Example 2 Listing All Ramdisks # ramdiskadm Block Device Size Removable /dev/ramdisk/miniroot 134217728 No /dev/ramdisk/certfs 1048576 No /dev/ramdisk/mydisk 2097152 Yes EXIT STATUS
ramdiskadm returns the following exit values: 0 Successful completion. >0 An error occurred. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsr | +-----------------------------+-----------------------------+ |Interface Stability |Evolving | +-----------------------------+-----------------------------+ SEE ALSO
attributes(5), ramdisk(7D) NOTES
The abilities of ramdiskadm and the privilege level of the person who uses the utility are controlled by the permissions of /dev/ramdiskctl. Read access allows query operations, for example, listing device information. Write access is required to do any state- changing operations, for example, creating or deleting ramdisks. As shipped, /dev/ramdiskctl is owned by root, in group sys, and mode 0644, so all users can do query operations but only root can perform state-changing operations. An administrator can give write access to non-privileged users, allowing them to add or delete ramdisks. How- ever, granting such ability entails considerable risk; such privileges should be given only to a trusted group. SunOS 5.11 25 Mar 2003 ramdiskadm(1M)
Check Out this Related Man Page
RDEV(8) Linux Programmer's Manual RDEV(8) NAME
rdev - query/set image root device, RAM disk size, or video mode SYNOPSIS
rdev [-Rrvh] [-o offset] [image [value [offset]]] rdev [-o offset] [image [root_device [offset]]] ramsize [-o offset] [image [size [offset]]] vidmode [-o offset] [image [mode [offset]]] rootflags [-o offset] [image [flags [offset]]] DESCRIPTION
With no arguments, rdev outputs an /etc/mtab line for the current root file system. With no arguments, ramsize, vidmode, and rootflags print usage information. In a bootable image for the Linux kernel on i386, there are several pairs of bytes which specify the root device, the video mode, and the size of the RAM disk. These pairs of bytes, by default, begin at offset 504 (decimal) in the kernel image: 498 Root flags (500 and 502 Reserved) 504 RAM Disk Size 506 VGA Mode 508 Root Device (510 Boot Signature) rdev will change these values. Typical values for the image parameter, which is a bootable Linux kernel image, might be: /vmlinux /vmunix /boot/bzImage-2.4.0 /dev/fd0 /dev/fd1 When using the rdev command, the root_device parameter might be something like: /dev/hda1 /dev/hdf13 /dev/sda2 /dev/sdc4 /dev/ida/c0d0p1 One may also specify the device by a comma-separated pair of decimal integers major,minor. For the ramsize command, the size parameter specifies the size of the RAM disk in kilobytes. 2.0.x kernels and newer dynamically allocate the ramdisk and do not need this setting. For the rootflags command, the flags parameter contains extra information used when mounting root. Currently the only effect of these flags is to force the kernel to mount the root filesystem in readonly mode if flags is non-zero. For the vidmode command, the mode parameter specifies the video mode: -3 = Prompt -2 = Extended VGA -1 = Normal VGA 0 = as if "0" was pressed at the prompt 1 = as if "1" was pressed at the prompt 2 = as if "2" was pressed at the prompt n = as if "n" was pressed at the prompt If the value is not specified, the image will be examined to determine the current settings. OPTIONS
-r Causes rdev to act like ramsize (Not relevant for 2.0.x and newer kernels). -R Causes rdev to act like rootflags. -v Causes rdev to act like vidmode. -h Provides help. BUGS
The rdev utility, when used other than to find a name for the current root device, is an ancient hack that works by patching a kernel image at a magic offset with magic numbers. It does not work on architectures other than i386. Its use is strongly discouraged. Use a boot loader like SysLinux or LILO instead. HISTORY
At offset 502 there used to be the device number of the swap device (in Linux 0.12), and "rdev -s" or "swapdev" would set this. However, since Linux 0.95 this constant is not used any longer, and the swap device is specified using the swapon(2) system call. At offset 504 there used to be the size of the ramdisk in kilobytes. One would specify a size, and this much was grabbed off the top of memory. In Linux 1.1.39 it became also possible to set this value on the kernel command line. In Linux 1.3.48 the ramdisk setup was changed. Ramdisk memory is now taken from the buffer cache, so that the ramdisk can grow dynamically. The interpretation of the ramdisk word was changed to a word of which the high order bit is a prompt flag (1: prompt for ramdisk: "VFS: Insert ramdisk floppy and press ENTER" - this is needed with a two-floppy boot), the next bit a load flag (1: load ramdisk), and the low order 11 bits give the starting block number of the root filesystem image (so that one can have a single floppy boot). See also linux/Documentation/ramdisk.txt. AUTHORS
Originally by Werner Almesberger (almesber@nessie.cs.id.ethz.ch) Modified by Peter MacDonald (pmacdona@sanjuan.UVic.CA) rootflags support added by Stephen Tweedie (sct@dcs.ed.ac.uk) AVAILABILITY
The rdev command is part of the util-linux-ng package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/. Linux 0.99 20 November 1993 RDEV(8)