RFR: 8200203: Missing platform definitions for ia64

[Magnus Ihse Bursie]

On 2018-03-26 03:06, John Paul Adrian Glaubitz wrote:
> On 03/26/2018 08:08 AM, David Holmes wrote:
>> Everytime I see these zero-only platform definitions it makes we think we really
>> should have these isolated into a zero-specific file. At the moment this can
>> paint a false picture that all these platforms have full OpenJDK ports available.
> Is that really the case though? If someone is reading the platform.m4 file, they
> might think that but simply trying to build the server variant for ia64 would
> fail very quickly anyway and people would realize it's not supported.
>
> In the end, I think the extended portability OpenJDK highly outweighs your
> reservations above. Someone who doesn't understand the difference between Zero
> and the official ports, is also unlikely to try building OpenJDK from source
> themselves.
I agree. I don't think it's a problem that we list the zero platforms in 
platform.m4.
>
>> I also wonder if the values here can be reliably obtained via uname/sysconf
>> or some such utility so that we don't have to list every single platform
>> individually?
> I think autoconf normally has support for this, yes. It's rather unusual
> having to add targets manually. But you will need the mapping to VAR_CPU,
> for example. I will have a look at it anyway.
You can consider platform.m4 (amongst other thing) to be a "translation" 
between whatever autoconf calls a platform, and what OpenJDK has 
traditionally used. For some platforms, this is a no-brainer, but for 
other, there are unfortunately multiple, well-accepted names (amd64, 
x86_64, x64), and the choice OpenJDK made in the past was not always 
aligned with the uname/sysconf/autoconf name.

Despite our best efforts, we are still plagued by having different names 
in different places.

We could perhaps try to make a "generic" section that maps OpenJDK names 
and values directly to what's given by the system, and use it whereever 
it applies. I'm not sure how to extract the endianness, though..

> For the time being, it would be nice if I can get this and a second follow-up
> change for ia64 merged so downstream (currently Debian and Gentoo for ia64)
> doesn't have to carry any additional patches anymore.
Your patch looks good to me.

/Magnus
>
> Thanks,
> Adrian
>