POSIX.1 (FIPS 151-2) Certification
A Historic Development for Linux
By Ian Nandrha, Lasermoon Ltd.
Linux-FT is the first Linux distribution to be Certified against a
recognised, industry standard - POSIX.1 (FIPS 151-2)
Before we discuss the full details, a little background to Linux and
POSIX. Full details of this certification and release can be obtained by
replying to firstname.lastname@example.org
or from http://www.lasermoon.co.uk
Distribution details and mirror sites appear at the end of this announcement.
Linux is often described as "POSIX-ish", "Mostly POSIX" and other
equally imprecise terms. Magazine articles sometimes describe Linux as
POSIX Compliant. Whilst Linux has certainly been developed towards POSIX
standards, it has only now been Certified to an POSIX standard. POSIX
"Compliance", "POSIX'ish" and other terms only provide an indication
that POSIX standards may have been referred to during development.
Unlike the term UNIX, which can only be used to describe products that
pass the X/Open validation suites, the term POSIX can be used with
freedom as there is no governing body to regulate its use - or misuse.
The message (POSIX) displayed when some Linux boots
is meaningless as it does not define which POSIX standard it refers to
or if it has been certified. At best, the Linux displaying the (POSIX)
message has been developed towards POSIX standards and is at worst
deliberately misleading. To the best of our knowledge, this is the first
time that Linux has actually been tested and passed against the real
POSIX test suites. Linux-FT has been certified against POSIX.1
What's Conformance Testing?
Essentially the product is tested against validation software produced
and released by a standards body and validated by an Independent
Current Linux distributions are "tested" on the Internet (we actually
heard a comment along the lines of ".. we don't need Conformal Testing,
we have the best testing in the world on the Internet." Without opening
the debate about Internet testing, Conformal Testing and Certification...
POSIX.1 FIPS 151-2 Certification
This is a milestone in Linux development. For the first time a Linux has
been certified against an International standard, POSIX.1 (FIPS 151-2)
The reasons for certification are simple :
- Conformance is essential for Linux's continued adoption and
- Conformance permits easier Support
- Conformance significantly adds to the Feel Good factor for Linux.
We now have something to measure Linux against. We can start to
measure quality. We can determine if a given Linux "works".
The decision to actually Certify Linux was made to remove the criticism
that Linux is not a real, stable and serious operating system. It has
widely accepted that Linux requires major Applications to be ported to
it. Currently ISV's (Independent Software Vendors) have little
real proof that Linux will actually support their applications if they
choose to invest time and money into a port. There is also a continual
fear in the ISV community that Linux will have changed during the
porting process (which can take 3 months) compromising their investment.
For Linux to have a wide base of stable applications, the ISV community
have to have proof that Linux is a credible platform to port onto.
POSIX.1 certification provides this proof in the following ways :
POSIX.1 Certification also makes it easier for large
organisations to use Linux as the "It's not tested" argument
is now clearly not true.
- It proves that there are organisations in the Linux world that
take quality, standards and consistency seriously enough to
actually obtain recognised standards accreditation.
- It provides a level of stability. Certification is a long and
costly process which is simply not possible to repeat with the
same rate of change of Linux. Put more simply, things have
slowed down enough for ISV's to port with confidence.
- It PROVES that Linux has been tested. The often quoted
"..we have the best testing in the world on the Internet.." carries
little weight with ISV's, especially when no test results can be
A Stable Platform
An Application is only as good as the platform supporting it and ISV's
require a stable operating system with consistent and known
specification. Providing a specification for Linux has historically been
a problem which has discouraged both ISV's from porting and
organisations from using Linux. POSIX.1 certification gives the level of
standardisation and consistency required to overcome such objections and
makes Linux a more attractive alternative.
The Feel Good Factor
Standards accreditation does not imply high quality or reliability,
although a certified system will always be better tested than a
non-certified system. It can be argued (and often is) that an
unreliable, inefficient system can pass certification. True, it is not a
measure of quality, but it is an independent assessment of functionality.
Put more simply: you have an independent body saying that it works. It
also means that products will be easier to port, more consistent and
stable It means that a future release, Certified to the same
standard, will perform and behave in the same way as its predecessor.
It also shows that Linux is maturing, distancing it from situations
where it is being misrepresented - there is at least one advertisement
describing Linux as being "100% UNIX", a statement which is both illegal
and dangerously misleading.
Consistent, Stable and Standard
Companies porting to Linux can now do so knowing that future releases
will behave in a consistent manner. This standardised functionality
makes support easier as there is a standard against which "bugs" can be
Which Linux's are Certified?
At present only Linux-FT and discussions are proceeding
with Linus Torvalds about ensuring that the considerable investment in
the certification process is fed back into future Linux kernels.
We will be working with Linus to ensure that new kernels have passed the
tests required for certification.
There is more to POSIX.1 certification than just the kernel. The
complier has been enhanced, Libraries upgraded in addition to countless
other major and minor code changes.
If you are in any doubt if a Linux distribution is certified, ask to see
the POSIX Conformance document and Certificate.
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