RFR: JDK-8036003: Add --with-debug-symbols=[none|internal|external|zipped]

[Magnus Ihse Bursie]

On 2015-11-21 14:12, Yasumasa Suenaga wrote:
>> My point with current proposal is that either it doesn't touch the 
>> zipping because we already have an option for that; or it should 
>> deprecate the existing option (now Erik has pointed out that 
>> capability).
>
> I'm using BASIC_DEPRECATED_ARG_ENABLE for debug-symbols and 
> zip-debug-info in new webrev:
>   http://cr.openjdk.java.net/~ysuenaga/JDK-8036003/webrev.03/
>
> I had thought this new option as a wrapper for existing options.
> However, if current options should be deprecated, I will follow it.

Hi Yasumasa,

Sorry for the delay in my response.

I had to go back and re-read the old discussions and my personal notes 
about this. It turned out that some of the complications that existed 
then is not relevant from Oracle's point of view anymore (more 
specifically, stripping to several distinct levels). With that 
complication gone, the basic case boils down to the three ways of doing 
this:
1) Compile without debug information ("none")
2) Compile with debug information and keep it ("internal")
3) Compile with debug information, copy it to an external file, and 
strip the binary ("external")

So far, so good. I agree with David Holmes that the zipping complicates 
things somewhat. The problem here is two-fold: Firstly, I believe that 
the "external" choice will be relevant to nobody (as in, neither the 
community nor Oracle), and secondly, there have been discussions of 
handling the external debuginfo differently (namely, to move all debug 
info, unzipped, into a separate image, and zip them all at once). It's a 
bit unfortunate if we create an interface to configure that cannot grow 
properly with future changes.

On the other hand, it does seem convenient to express the end result for 
the Oracle build as "zipped" (or possibly "external-zipped", to 
emphasize  the connection to "external"?).

So I'm not sure what to think myself. But if David agrees that adding 
"zipped" (or "external-zipped") to the new argument, and deprecating the 
old, then I agree with it as well. :-)

The second discussion here is the connection between java and native 
debug symbols.

Fact: We do not currently have a story for setting java debug symbols. 
That's bad, and a regression as pointed out.
Fact: That does not mean it has to be fixed in this patch.

I do think that java and native debug symbols are different things and 
should be treated differently. But I also think we should have configure 
arguments that show their similarity. So, I propose that we have a
--with-native-debug-symbols=none,internal,external,zipped
as you propose, and then also a
--with-java-debug-symbols=none,all
(or "none,internal" for consistency).

I think it would be nice if that flag could be implemented in the same 
patch, but since it is a different thing I understand if you want to 
leave it out. There is some added complication here, since we already 
set -g for java compilation depending on debug level, and the native 
debug symbol patch is obviously tricky as it is.

/Magnus