|This version of this document is no longer maintained. For the latest documentation, see http://www.qnx.com/developers/docs.|
Driver for RAM disk interface (QNX Neutrino)
|You must be root to start this driver.|
devb-ram [cam option[,option]...] [disk option[,option]...] [ram option[,option]...] [blk option[,option]...] &
|Use commas (,) to separate the options. You can put the cam, disk, ram, and blk groups of options in any order.|
- Be quiet: don't display any information on startup.
- Be verbose.
The ram options control the driver's interface to RAM:
- The physical address to overlay. The default is not to overlay.
- Set the sector size. The default is 512 bytes.
- Specify the capacity of the RAM drive in the blocks of the size specified by the blksize option. The default is 4096 blocks (2 MB).
- Don't partition the RAM disk or format a QNX 4 filesystem on it.
The devb-ram driver creates a RAM disk interface. When the capacity option isn't specified, devb-ram creates a 2 MB RAM disk.
By default, devb-ram partitions the RAM disk, leaving one block for the partition table itself, and making the remainder of the RAM disk (capacity minus 1) a t77 partition, which it then initializes (internally, not by spawning dinit) to have a blank fs-qnx4.so filesystem on it. If you specify the nodinit option, you can later manually format it, optionally partition the RAM disk with fdisk (but you can make the whole thing a filesystem), and then mount it.
Create a 4 MB RAM drive:
devb-ram ram capacity=8192 &
The devb-ram driver causes io-blk.so to adopt various block special devices under /dev. These devices are normally named hdn, where n is the physical unit number of the device.
This driver could also require the following shared objects:
|cam-disk.so||For RAM disk access.|
The devb-ram driver terminates only if an error occurs during startup, or if it has successfully forked itself upon startup because it hadn't been initially started in the background.
- The devb-ram driver wasn't started in the background and therefore forked itself. The original process terminated with a zero exit status, the forked process continued.
- > 0
- An error occurred during startup.
While there's no limit to the size of a disk or partition, I/O (i.e. the lseek(), read() and write() functions) is currently limited to 2 gigabytes per partition (or disk). This I/O limit has no effect on the partition size for mounted filesystems.
Known supported functions include:
chmod(), chown(), close(), closedir(), creat(), devctl(), dup(), dup2(), fcntl(), fpathconf(), fstat(), lseek(), mkdir(), mkfifo(), mknod(), open(), opendir(), pathconf(), read(), readdir(), readlink(), rewinddir(), rmdir(), stat(), symlink(), unlink() (not supported for directories), utime(), write()