Heads Up: JDK 7 Linux platforms moving to Fedora 9

[Andrew Haley]

Martin Buchholz wrote:
> On Fri, Dec 19, 2008 at 10:27, Andrew Haley <aph at redhat.com> wrote:
>> As an example of the cost of building on old boxes, OpenJDK contains
>> prototypes for epoll(7) that are incorrect for some arches.  These
> 
> We are changing the subject slightly from portability of binaries
> to portability of sources.
> 
>> prototypes exist because epoll didn't come into existence before
>> Kernel 2.6(ish), and OpenJDK was being built on an old box, so the
>> prototypes were copied from the kernel headers on (I think) an x86
>> box.  This bug causes bizarre and hard to debug behaviour on non-x86
>> arches.
>>
>> At some point you have to get rid of cruft like this.  If not now,
>> when?
> 
> Obviously opinions differ on how long to support older platforms.
> 
> "Kids these days..." think 2 years is old.
> 
> When I was maintaining an open source project,
> I tried to maintain a portability horizon of at least 10 years.
> Seriously.  I would like people to be able to build my
> software on that old Irix machine they picked up at a
> garage sale.

Well, we have to distinguish between what you like and what is best
for the project as a whole!  There's a nice note by Dijkstra called
"On the fact that the Atlantic Ocean has two sides" where he ruminates
about the Buxton Index:

"A very useful measure is —called after its inventor— the "Buxton
Index". John N. Buxton discovered that the most important
one-dimensional scale along which persons are institutions to be
compared, can be placed is the length of the period of time in the
future for which a person or institution plans. This period, measured
in years, gives the Buxton Index.

"The great significance of the Buxton Index is not its depth, but its
objectivity. The point is that when people with drastically different
Buxton Indices have to cooperate while unaware of the concept of the
Buxton Index, they tend to make moral accusations against each
other. The man with the shorter Buxton Index accuses the other of
neglect of duty, the man with the larger one accuses the other of
shortsightedness. The notion of the Buxton Index takes the moral
flavour away and enables people to discuss such differences among
themselves dispassionately. There is nothing wrong with having
different Buxton Indices! It takes many people to make a world. There
is clearly no moral value attached to either a long or a short Buxton
Index."

I am aware that we are here talking about time projected into the past,
not the future, but I think the situation is very similar.  You might
think that I am very aggressive with obsoleting old versions, while I
might think you are hanging onto dead softwtare for no good reason.

> For problems like changing prototypes, we have configure.
>
> Sure the following example is ugly cruft,
> but we can wait one more decade before nuking it.

We can, but should we?  :-)

Andrew.