Building on platforms other than Linux

Building on platforms other than Linux

[Benno]

Hi,

I was wondering if there were any, in priniciple, objections
to making the Linux kernel buildable on different Unix-like 
platforms?

I am currently compiling on MacOSX and this, for the most part was
fairly straightforward and simple. The biggest gotcha I had was
that libkconfig is compiled as a shared library, and unfortunately shared
libraries are done quite different on different systems. Specifically MacOSX
doesn't support gcc -shared.

libkconfig.so appears to be the only shared library created in the
build system, and given that it is only about 95K, and that you don't
often run two copies of conf at once, it doesn't seem to buy much.

The only other reason for doing it this way is to provide a plugin
style architecture but this doesn't appear evident. gconf and qconf
appear to manually load libkconfig.so (rather than linking against
it), but in both cases it appears to be the very first thing they
do is explicitly load libconfig.

It would seem that using static libraries would enhance portability,
and produce a simpler build system, however I expect I am missing some
other reasons.

In summary two questions:

1: Is portability of the build system a desirable property?

2: If so, is moving to static libraries a valid way of achieving this?

Thanks,

Benno

Re: Building on platforms other than Linux

[Sam Ravnborg]

On Wed, Aug 11, 2004 at 07:13:49PM +1000, Benno wrote:
> Hi,
> 
> I was wondering if there were any, in priniciple, objections
> to making the Linux kernel buildable on different Unix-like 
> platforms?

The userbase for building kernels are only increasing and there
continue to be more focus from the embedded people.
Having experince in this field first-hand tells me that a kernel
that can be build on several paltforms are a good thing.

For kbuild you will at some point start to see patches so at least
the build system does not restrict us to Linux alone.

People on this list usually reply: "shift development to a Linux
based platform". This is for many developers a nice dream,
but they are restricted by coporate rules etc.

So please feed patches to this list with your findings.

> 
> I am currently compiling on MacOSX and this, for the most part was
> fairly straightforward and simple. The biggest gotcha I had was
> that libkconfig is compiled as a shared library, and unfortunately shared
> libraries are done quite different on different systems. Specifically MacOSX
> doesn't support gcc -shared.

Please submit a patch for this and make sure to include Roman Zippel, he
is the maintainer of kconfig.

[I recall RedHat already disables the shared library??]

	Sam

Re: Building on platforms other than Linux

[Arjan van de Ven]

[-- Attachment #1: Type: text/plain, Size: 103 bytes --]


> [I recall Red Hat already disables the shared library??]

we don't do no such thing, sir. :-)


[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

Re: Building on platforms other than Linux

[Sam Ravnborg]

On Wed, Aug 11, 2004 at 09:03:11PM +0200, Arjan van de Ven wrote:
> 
> > [I recall Red Hat already disables the shared library??]
> 
> we don't do no such thing, sir. :-)

OK.

It was the following patch that I recalled seeing:
http://marc.theaimsgroup.com/?l=linux-kernel&m=108599543602571&w=2

One day I may land a non-interactive frontend for kconfig, so
we can have this functionality added in the kernel proper.

	Sam

[PATCH] Re: Building on platforms other than Linux

[Benno]

[-- Attachment #1: Type: text/plain, Size: 1798 bytes --]

On Wed Aug 11, 2004 at 20:54:53 +0200, Sam Ravnborg wrote:
>On Wed, Aug 11, 2004 at 07:13:49PM +1000, Benno wrote:
>> Hi,
>> 
>> I was wondering if there were any, in priniciple, objections
>> to making the Linux kernel buildable on different Unix-like 
>> platforms?
>
>The userbase for building kernels are only increasing and there
>continue to be more focus from the embedded people.
>Having experince in this field first-hand tells me that a kernel
>that can be build on several paltforms are a good thing.

This is the direction I am coming from.

>For kbuild you will at some point start to see patches so at least
>the build system does not restrict us to Linux alone.

Great.

>People on this list usually reply: "shift development to a Linux
>based platform". This is for many developers a nice dream,
>but they are restricted by coporate rules etc.
>
>So please feed patches to this list with your findings.
>
>> 
>> I am currently compiling on MacOSX and this, for the most part was
>> fairly straightforward and simple. The biggest gotcha I had was
>> that libkconfig is compiled as a shared library, and unfortunately shared
>> libraries are done quite different on different systems. Specifically MacOSX
>> doesn't support gcc -shared.
>
>Please submit a patch for this and make sure to include Roman Zippel, he
>is the maintainer of kconfig.

Attached is a patch to avoid using shared libraries in the build system. 
It is very simple, instead of [m]conf linked against libkconfig.so, they
directly link against $(libkconfig-objs).

For (g|q)conf they no longer use dl_open and also directly link against 
$(libkconfig-objs). (Achieved by export LKC_DIRECT_LINK to the compile.)

(Give this change one could also get rid of rules to build .so files
in Makefile.lib)

Cheers,

Benno

[-- Attachment #2: no_shared.diff --]
[-- Type: text/plain, Size: 1342 bytes --]

--- ../../../linux-2.6.7/scripts/kconfig/Makefile	2004-06-16 15:20:26.000000000 +1000
+++ Makefile	2004-08-12 09:53:15.000000000 +1000
@@ -68,8 +68,8 @@
 libkconfig-objs := zconf.tab.o
 
 host-progs	:= conf mconf qconf gconf
-conf-objs	:= conf.o  libkconfig.so
-mconf-objs	:= mconf.o libkconfig.so
+conf-objs	:= conf.o  $(libkconfig-objs)
+mconf-objs	:= mconf.o $(libkconfig-objs)
 
 ifeq ($(MAKECMDGOALS),xconfig)
 	qconf-target := 1
@@ -81,11 +81,11 @@
 
 ifeq ($(qconf-target),1)
 qconf-cxxobjs	:= qconf.o
-qconf-objs	:= kconfig_load.o
+qconf-objs	:= $(libkconfig-objs)
 endif
 
 ifeq ($(gconf-target),1)
-gconf-objs	:= gconf.o kconfig_load.o
+gconf-objs	:= gconf.o $(libkconfig-objs)
 endif
 
 clean-files	:= libkconfig.so lkc_defs.h qconf.moc .tmp_qtcheck \
@@ -96,10 +96,10 @@
 HOSTCFLAGS_zconf.tab.o	:= -I$(src)
 
 HOSTLOADLIBES_qconf	= -L$(QTLIBPATH) -Wl,-rpath,$(QTLIBPATH) -l$(QTLIB) -ldl
-HOSTCXXFLAGS_qconf.o	= -I$(QTDIR)/include 
+HOSTCXXFLAGS_qconf.o	= -DLKC_DIRECT_LINK -I$(QTDIR)/include 
 
 HOSTLOADLIBES_gconf	= `pkg-config gtk+-2.0 gmodule-2.0 libglade-2.0 --libs`
-HOSTCFLAGS_gconf.o	= `pkg-config gtk+-2.0 gmodule-2.0 libglade-2.0 --cflags`
+HOSTCFLAGS_gconf.o	= -DLKC_DIRECT_LINK `pkg-config gtk+-2.0 gmodule-2.0 libglade-2.0 --cflags`
 
 $(obj)/conf.o $(obj)/mconf.o $(obj)/qconf.o $(obj)/gconf.o: $(obj)/zconf.tab.h