Re: OS/2: command-line length limit

[Ralf Wildenhues]

* KO Myung-Hun wrote on Fri, Dec 17, 2010 at 01:20:38PM CET:
> Ralf Wildenhues wrote:
> > * KO Myung-Hun wrote on Sun, Nov 28, 2010 at 07:20:32AM CET:
> >> --- libltdl/m4/libtool.m4.org      2010-09-22 17:41:18.000000000 +0900
> >> +++ libltdl/m4/libtool.m4  2010-11-27 16:03:50.000000000 +0900
> >> @@ -1624,6 +1624,9 @@
> >>        lt_cv_sys_max_cmd_len=32768
> >>      fi
> >>      ;;
> >> +  os2*)
> >> +    lt_cv_sys_max_cmd_len=-1
> >> +    ;;
> >>    *)
> >>      lt_cv_sys_max_cmd_len=`(getconf ARG_MAX) 2> /dev/null`
> >>      if test -n "$lt_cv_sys_max_cmd_len"; then
> > 
> > Is there really no maximum for the command line length on OS/2?
> 
> It depends on a shell. I know, a default shell, cmd.exe, has 1024 length
> limit. But 4OS2.exe has other limit.
> In case of pdksh which is used really, it seems to have no limits.
> Although a computed length by libtool is 8192, it could handle a longer
> command line than 8192.

Well, what the Libtool macros do is compute a limit (that depends on
your current environment), and then only take a fraction of that, half
or so, to cope with additional environment.  If it computes 8192, then
chances are that your actual limit is not all that much higher.

Does the computation of the limit take very long?  Because if not, then
I'm inclined to leave it in and drop the above patch, as then a later
improvement to the limit will help users immediately.

> When porting VLC to OS/2, qt4 module needed a very long command line. So
> libtool try to create a reload object. The maximum length was 8192 at
> that time. Setting it to -1 does not need a reload object.

Does using the reload object work, or does it fail?
Users get fairly annoyed if the build fails due to the command line
length limit is actually exceeded.  We also need to think about users of
other packages, not just VLC, where the list may be much higher.

Thanks,
Ralf