I just pushed the first example of a configure script

[David Holmes]

Hi Fredrik,

I guess I'll have to reserve judgment but I don't like the idea of having to 
setup different build directories in which to run configure for local vs 
cross-compile - so far that's not making my job (as a developer) any easier.

As for using configure to detect capabilities ... that seems like a massive 
task and I'm not at all sure how far you can go with it. I think we would 
get further by refactoring into POSIX based code and then configure only 
need identify that the right POSIX API level is supported. Anyway this seems 
like it requires significant reworking of the source code. It will be 
interesting to see how this progresses.

Cheers,
David



On 22/08/2011 7:13 PM, Fredrik Öhrström wrote:
>
> ----- David.Holmes at oracle.com skrev:
>
>> Hi Fredrik,
>>
>> Can you clarify something please regarding the division of
>> responsibility
>> for configure-time versus build-time. It sounds from what you wrote
>> that you
>> need to run configure one-way to prepare to do cross-compilation
>> builds, and
>> another way to do local builds - is that the case?
>
> Yes, the standard way of configuring a local build is simply:
>
> ./configure
>
> this will setup a build for the local machine using locally
> discovered build dependencies, libs, ant, compilers etc etc.
> This is what most external OpenJDK developers would like to have.
> A friendly tool that goes actively looking for the needed
> build dependencies.
>
> To setup a cross compilation on the local machine to build
> an openjdk that runs on the sparc/solaris platform:
>
> ./configure --host=sparc-sun-solaris2.10
>
> This will scan the local machine for cross-compilers and
> tools (instead of gcc, it will prefer sparc-sun-solaris2.10-gcc
> if it is found in the path.) You also need a sysroot
> for headers and libraries. Usually the sysroot path is encoded
> into the cross-compiler binaries.
>
> Inside Oracle we can also do:
>
> ./configure --host=sparc-sun-solaris2.10 --with-builddeps-server=ftp://ourbuilddeps.server
>
> You can of course use the builddeps server for non-cross compile builds.
> ./configure --with-builddeps-server=ftp://ourbuilddeps.server
> this is useful for building the OpenJDK using a standardized
> compiler and standardized headers and libraries.
> These will be stored locally on your machine which means that
> you can disconnect your laptop from the network and still build.
>
> Now, another important reason for moving to configure is to move
> towards capabilities detection instead of the groups Solaris/Linux/Windows.
>
> I have been told that AIX for example, half of the time behaves like Solaris
> and half of the time like Linux, which makes it very time consuming
> to create a port for that operating system. If we use
> ifdefs that check for particular behaviour instead of which group of OS
> the intendend host is, then porting will be much much simpler!
>
> Since capabilities testing can take a bit of time (the are often small
> test programs that check what headers and libs exists and what
> functions exist in the libs). It makes sense to move the testing
> out from the makefiles to the configure script. To avoid retesting
> at every make invocation.
>
> //Fredrik