Shared object that supports the read-only compressed filesystem (QNX Neutrino)


driver … rcfs rcfs_options… &

Runs on:

QNX Neutrino


Set to the size of KiB allowed to cache the inode and file name table.
The maximum number of compression buffers that may be allocated at run time.
Minimize the number of compression buffers allocated.
The minimum number of compression buffers that are allocated at startup and maintained at runtime.
The default number of inodes to allocate for an extended (write-capable) volume.

In addition, you can specify any of the filesystem options described for io-blk.so.


The fs-rcfs.so shared object supports the read-only compressed filesystem. It's automatically loaded by the devb-* drivers when mounting an RCFS.

It’s a read-only filesystem that compresses the files in blocks, and still supports random access. The filesystem can be mounted from a disk partition, or from a file. The maximum file size supported is 2 GB, and the maximum filesystem size is 4 GB.

The RCFS has minimal write support; to enable write support, use the mount –uw command. Random writes aren't supported, but you can:

Summary of filesystem commands

The following table shows the shared objects and related commands for the filesystems:

Partition type Filesystem Shared object Initialize with: Check with:
1, 4, or 6 DOS fs-dos.so mkdosfs chkdosfs
7 Windows NTa fs-nt.so N/A N/A
11, 12, or 14 FAT32 fs-dos.so mkdosfs chkdosfs
77, 78, or 79 QNX 4 fs-qnx4.so dinit chkfsys
131 Linux (Ext2) fs-ext2.so N/A N/A
175 Apple Macintosh HFS or HFS Plusa fs-mac.so N/A N/A
177, 178, or 179 Power-Safe fs-qnx6.so mkqnx6fs chkqnx6fsb
  Read-only compressed (RCFS) fs-rcfs.so mkrcfs N/A

a Read-only.

b Not usually necessary.

For more information, see the Filesystems chapter of the System Architecture guide.