QNX 4 compatible filesystem support
driver ... qnx4 qnx4_options... &
Where driver is any of the devb-* drivers,
and qnx4_options is one or more of the following,
separated by commas:
- When to pre-read the .bitmap file.
Scanning the bitmap is required to return the count of free blocks.
It also allows for improved
performance by creating an in-memory summary of
where free blocks might be located within the filesystem.
The value must be one of the following:
- always — calculate/store .bitmap
details for all media.
- lazy — don't read the bitmap for
non-removable media at mount time, but when it's first needed (e.g. by a
This can help speed up system boot times (since on a large disk, the
.bitmap files may be several megabytes in length,
and if read right away, can interfere with the starting of other
processes on an embedded system).
- nonrmv (the default) — act as always for
nonremovable media, and lazy for removable media
- Allow persistent over-grown files; don't truncate them when they're
Certain file-write access patterns (e.g O_APPEND) are
detected, and the file isn't shrunk back at the last close.
This is useful for log files that you keep appending to, and so on.
- Never embed inode details; always place in fixed-size
- Enable a more aggressive file-extent over-allocation heuristic.
- Attempt to repair any file marked as “busy”
on the filesystem (i.e. a file that was being grown or shrunk when the system
was improperly shutdown). The default action is to return
EBADFSYS to any attempt to open such a file; this option
will instead truncate the file to its last-known valid size, unset the
“busy” indicator, and allow access. This truncation may result in
lost data and unused blocks marked as used in the bitmap,
so run chkfsys later to ensure full filesystem consistency.
In addition, you can specify any of the
The fs-qnx4.so shared object provides support for QNX 4 filesystems.
It's automatically loaded by the devb-*
drivers when mounting a QNX 4 filesystem.
The following table shows the shared objects and related commands for
b Not usually necessary.
For more information, see the
chapter of the System Architecture guide.
- To enable support for long filenames (more than 48 characters) on an
existing QNX 4 compatible filesystem, login as root and
create an empty, read-only file named .longfilenames in
the root directory of that filesystem.
To enable support for long filenames on a new QNX 4 filesystem, use the
-N option to
chapter of System Architecture
QNX Neutrino User's Guide: