Re: --enable-auto-image-base linker option for Cygwin

[John W. Eaton]

On 14-Jul-2005, James R. Phillips wrote:

| --- "John W. Eaton"  wrote:
| > 
| > I can apply the following change if it solves a real problem.  Is
| > there any disadvantage to making this change?
| > 
| 
| It is hard for me to characterize the problem as real, because I haven't seen
| it on this build.  However, the design of the cygwin fork() is such that it
| isn't able to rule out the possibility of dll address collisions, leading to
| failure of the fork.  The change is such that it should reduce the probability
| of such collisions.  At this point I would classify it as a beneficial change
| to prevent a potential issue.
| 
| There is currently no downside to the change that I am aware of.  cgf has made
| some changes to cygwin ld in the past week to eliminate what were some 
possible
| downsides.
| 
| Would it be possible to also add this linker option to the set of default
| options that are used for cygwin in the mkoctfile script?  It does not appear
| to me that this configuration change will propagate into the makoctfile
| defaults.

I think the change I proposed should also affect mkoctfile because
mkoctfile has

: ${DL_LDFLAGS=%OCTAVE_CONF_MKOCTFILE_DL_LDFLAGS%}

and the rules in Makeconf.in and Makefile.in will substitute the value
of 

  $(MKOCTFILE_DL_LDFLAGS)

for

  %OCTAVE_CONF_MKOCTFILE_DL_LDFLAGS%

and configure.in has

  DL_LDFLAGS='$(SH_LDFLAGS)'
  MKOCTFILE_DL_LDFLAGS='$(DL_LDFLAGS)'

so the default value of DL_LDFLAGS in mkoctfile should be the same as
SH_LDFLAGS unless we specifically set DL_LDFLAGS or
MKOCTFILE_DL_LDFLAGS to something different in configure.in (some
platforms do, but not Cygwin).

| In any case, I think the way to handle this is to add the change to whatever
| set of changes you are going to make for the next point release.  Please don't
| think this is significant enough on its own to merit a new octave point
| release.

OK.

I've checked in the changes.

Thanks,

jwe