574 lines
25 KiB
Plaintext
Executable File
574 lines
25 KiB
Plaintext
Executable File
On Configuring Development Tools
|
|
|
|
K. Richard Pixley
|
|
Cygnus Support
|
|
|
|
Last Mod 19 Jul 1991 by gnu@cygnus.com
|
|
|
|
INTRO
|
|
-----
|
|
|
|
This document attempts to describe the general concepts behind
|
|
configuration of the Cygnus Support release of the GNU Development
|
|
Tools. It also discusses common usage. Eventually, FIXME, there
|
|
will also be a man page for "configure", an "info" tree, etc.
|
|
|
|
|
|
BASICS
|
|
------
|
|
|
|
Some Basic Terms:
|
|
|
|
There are a lot of terms that are frequently used when discussing
|
|
development tools. Most of the common terms have been used for
|
|
several different concepts such that their meanings have become
|
|
ambiguous to the point of being confusing. Typically, we only
|
|
guess at their meanings from context and we frequently guess
|
|
wrong.
|
|
|
|
This document uses very few terms by comparison. The intent is to
|
|
make the concepts as clear as possible in order to convey the
|
|
usage and intent of these tools.
|
|
|
|
"Programs" run on "machines". Programs are very nearly always
|
|
written in "source". Programs are "built" from source.
|
|
"Compilation" is a process that is frequently, but not always,
|
|
used when building programs.
|
|
|
|
|
|
Host Environments:
|
|
|
|
In this document, the word "host" refers to the environment in
|
|
which this source will be compiled. "host" and "host name" have
|
|
nothing to do with the proper name of your host, like "ucbvax",
|
|
"prep.ai.mit.edu" or "att.com". Instead they refer to things like
|
|
"sun4" and "dec3100".
|
|
|
|
Forget for a moment that this particular directory of source is
|
|
the source for a development environment. Instead, pretend that
|
|
it is the source for a simpler, more mundane, application, say, a
|
|
desk calculator.
|
|
|
|
Source that can be compiled in more than one environment,
|
|
generally needs to be set up for each environment explicitly.
|
|
Here we refer to that process as configuration. That is, we
|
|
configure the source for a host.
|
|
|
|
For example, if we wanted to configure our mythical desk
|
|
calculator to compile on a SparcStation, we might configure for
|
|
host sun4. With our configuration system:
|
|
|
|
cd desk-calculator ; ./configure sun4
|
|
|
|
does the trick. "configure" is a shell script that sets up
|
|
Makefiles, subdirectories, and symbolic links appropriate for
|
|
compiling the source on a sun4.
|
|
|
|
The "host" environment does not necessarily refer to the machine
|
|
on which the tools are built. It is possible to provide a sun3
|
|
development environment on a sun4. If we wanted to use a cross
|
|
compiler on the sun4 to build a program intended to be run on a
|
|
sun3, we would configure the source for sun3.
|
|
|
|
cd desk-calculator ; ./configure sun3
|
|
|
|
The fact that we are actually building the program on a sun4 makes
|
|
no difference if the sun3 cross compiler presents an environment
|
|
that looks like a sun3 from the point of view of the desk
|
|
calculator source code. Specifically, the environment is a sun3
|
|
environment if the header files, predefined symbols, and libraries
|
|
appear as they do on a sun3.
|
|
|
|
Nor does the host environment refer to the the machine on which
|
|
the program to be built will run. It is possible to provide a
|
|
sun3 emulation environment on a sun4 such that programs built in a
|
|
sun3 development environment actually run on the sun4.
|
|
|
|
Host environment simply refers to the environment in which the
|
|
program will be built from the source.
|
|
|
|
|
|
Configuration Time Options:
|
|
|
|
Many programs have compile time options. That is, features of the
|
|
program that are either compiled into the program or not based on a
|
|
choice made by the person who builds the program. We refer to these
|
|
as "configuration options". For example, our desk calculator might be
|
|
capable of being compiled into a program that either uses infix
|
|
notation or postfix as a configuration option. For a sun3, chosing
|
|
infix might be:
|
|
|
|
./configure sun3 +notation=infix
|
|
|
|
while a sun4 with postfix might be:
|
|
|
|
./configure sun4 +notation=postfix
|
|
|
|
If we wanted to build both at the same time, in the same directory
|
|
structure, the intermediate pieces used in the build process must
|
|
be kept separate.
|
|
|
|
./configure sun4 +forcesubdirs +notation=postfix
|
|
./configure sun3 +forcesubdirs +notation=infix
|
|
|
|
will create subdirectories for the intermediate pieces of the sun4
|
|
and sun3 configurations. This is necessary as previous systems
|
|
were only capable of one configuration at a time. A second
|
|
configuration overwrote the first. We've chosen to retain this
|
|
behaviour so the "+forcesubdirs" configuration option is necessary
|
|
to get the new behaviour. The order of the arguments doesn't
|
|
matter. There should be exactly one argument without a leading
|
|
'+' sign and that argument will be assumed to be the host name.
|
|
|
|
From here on the examples will assume that you want to build the
|
|
tools "in place" and won't show the "+forcesubdirs" option, but
|
|
remember that it is available.
|
|
|
|
In order to actually install the program, the configuration system
|
|
needs to know where you would like the program installed. The
|
|
default location is /usr/local. We refer to this location as
|
|
$(destdir). All user visible programs will be installed in
|
|
$(destdir)/bin. All other programs and files will be installed in
|
|
a subdirectory of $(destdir)/lib.
|
|
|
|
You can elect to change $(destdir) only as a configuration time
|
|
option.
|
|
|
|
./configure sun4 +notation=postfix +destdir=/local
|
|
|
|
Will configure the source such that:
|
|
|
|
make install
|
|
|
|
will put it's programs in /local/bin and /local/lib/gcc. If you
|
|
change $(destdir) after building the source, you will need to:
|
|
|
|
make clean
|
|
|
|
before the change will be propogated properly. This is because
|
|
some tools need to know the locations of other tools.
|
|
|
|
With these concepts in mind, we can drop the desk calculator and
|
|
move on to the application that resides in these directories,
|
|
namely, the source to a development environment.
|
|
|
|
|
|
SPECIFICS
|
|
---------
|
|
|
|
The GNU Development Tools can be built on a wide variety of hosts.
|
|
So, of course, they must be configured. Like the last example,
|
|
|
|
./configure sun4 +destdir=/local
|
|
./configure sun3 +destdir=/local
|
|
|
|
will configure the source to be built in subdirectories, in order
|
|
to keep the intermediate pieces separate, and to be installed in
|
|
/local.
|
|
|
|
When built with suitable development environments, these will be
|
|
native tools. We'll explain the term "native" later.
|
|
|
|
|
|
BUILDING DEVELOPMENT ENVIRONMENTS
|
|
---------------------------------
|
|
|
|
The Cygnus Support GNU development tools can not only be built
|
|
with a number of host development environments, they can also be
|
|
configured to create a number of different development
|
|
environments on each of those hosts. We refer to a specific
|
|
development environment created as a "target". That is, the word
|
|
"target" refers to the development environment produced by
|
|
compiling this source and installing the resulting programs.
|
|
|
|
For the Cygnus Support GNU development tools, the default target
|
|
is the same as the host. That is, the development environment
|
|
produced is intended to be compatible with the environment used to
|
|
build the tools.
|
|
|
|
In the example above, we created two configurations, one for sun4
|
|
and one for sun3. The first configuration is expecting to be
|
|
built in a sun4 development environment, to create a sun4
|
|
development environment. It doesn't necessarily need to be built
|
|
on a sun4 if a sun4 development environment is available
|
|
elsewhere. Likewise, if the available sun4 development
|
|
environment produces executables intended for something other than
|
|
sun4, then the development environment built from this sun4
|
|
configuration will run on something other than a sun4. From the
|
|
point of view of the configuration system and the GNU development
|
|
tools source, this doesn't matter. What matters is that they will
|
|
be built in a sun4 environment.
|
|
|
|
Similarly, the second configuration given above is expecting to be
|
|
built in a sun3 development environment, to create a sun3
|
|
development environment.
|
|
|
|
The development environment produced, is a configuration time
|
|
option, just like $(destdir).
|
|
|
|
./configure sun4 +destdir=/local +target=sun3
|
|
./configure sun3 +destdir=/local +target=sun4
|
|
|
|
In this example, like before, we create two configurations. The
|
|
first is intended to be built in a sun4 environment, in
|
|
subdirectories, to be installed in /local. The second is intended
|
|
to be build in a sun3 environment, in subdirectories, to be
|
|
installed in /local.
|
|
|
|
Unlike the previous example, the first configuration will produce
|
|
a sun3 development environment, perhaps even suitable for building
|
|
the second configuration. Likewise, the second configuration will
|
|
produce a sun4 development environment, perhaps even suitable for
|
|
building the first configuration.
|
|
|
|
The development environment used to build these configurations
|
|
will determine the machines on which the resulting development
|
|
environments can be used.
|
|
|
|
|
|
A WALK THROUGH
|
|
--------------
|
|
|
|
Native Development Environments:
|
|
|
|
Let us assume for a moment that you have a sun4 and that with your
|
|
sun4 you received a development environment. This development
|
|
environment is intended to be run on your sun4 to build programs
|
|
that can be run on your sun4. You could, for instance, run this
|
|
development environment on your sun4 to build our example desk
|
|
calculator program. You could then run the desk calculator
|
|
program on your sun4.
|
|
|
|
The resulting desk calculator program is referred to as a "native"
|
|
program. The development environment itself is composed of native
|
|
programs that, when run, build other native programs. Any other
|
|
program is referred to as "foreign". Programs intended for other
|
|
machines are foreign programs.
|
|
|
|
This type of development environment, which is by far the most
|
|
common, is refered to as "native". That is, a native development
|
|
environment runs on some machine to build programs for that same
|
|
machine. The process of using a native development environment to
|
|
build native programs is called a "native" build.
|
|
|
|
./configure sun4
|
|
|
|
Will configure this source such that when built in a sun4
|
|
development environment, with a development environment that
|
|
builds programs intended to be run on sun4 machines, the programs
|
|
built will be native programs and the resulting development
|
|
environment will be a native development environment.
|
|
|
|
The development system that came with your sun4 is one such
|
|
environment. Using it to build the GNU Development Tools is a
|
|
very common activity and the resulting development environment is
|
|
very popular.
|
|
|
|
make all
|
|
|
|
will build the tools as configured and will assume that you want
|
|
to use the native development environment that came with your
|
|
machine.
|
|
|
|
Using a development environment to build a development environment
|
|
is called "bootstrapping". The Cygnus Support release of the GNU
|
|
Development Tools is capable of bootstrapping itself. This is a
|
|
very powerful feature that we'll return to later. For now, let's
|
|
pretend that you used the native development environment that came
|
|
with your sun4 to bootstrap the Cygnus Support release and let's
|
|
call the new development environment stage1.
|
|
|
|
Why bother? Well, most people find that the Cygnus Support
|
|
release builds programs that run faster and take up less space
|
|
than the native development environments that came with their
|
|
machines. Some people didn't get development environments with
|
|
their machines and some people just like using the GNU tools
|
|
better than using other tools.
|
|
|
|
While you're at it, if the GNU tools produce better programs, maybe
|
|
you should use them to build the GNU tools. It's a good idea, so
|
|
let's pretend that you do. Let's call the new development
|
|
environment stage2.
|
|
|
|
So far you've built a development environment, stage1, and you've
|
|
used stage1 to build a new, faster and smaller development
|
|
environment, stage2, but you haven't run any of the programs that
|
|
the GNU tools have built. You really don't yet know if these
|
|
tools work. Do you have any programs built with the GNU tools?
|
|
Yes, you do. stage2. What does that program do? It builds
|
|
programs. Ok, do you have any source handy to build into a
|
|
program? Yes, you do. The GNU tools themselves. In fact, if you
|
|
use stage2 to build the GNU tools again the resulting programs
|
|
should be identical to stage2. Let's pretend that you do and call
|
|
the new development environment stage3.
|
|
|
|
You've just completed what's called a "three stage boot". You now
|
|
have a small, fast, somewhat tested, development environment.
|
|
|
|
make bootstrap
|
|
|
|
will do a three stage boot across all tools and will compare
|
|
stage2 to stage3 and complain if they are not identical.
|
|
|
|
Once built,
|
|
|
|
make install
|
|
|
|
will install the development environment in the default location
|
|
or in $(destdir) if you specified an alternate when you
|
|
configured. In fact, you can skip the "make all" part and just
|
|
"make install" which will make sure that the development
|
|
environment is built before attempting to install anything. Even
|
|
better, for configurations where host is the same as target, like
|
|
this one, "make install" will make sure that a "make bootstrap" is
|
|
done before installing anything.
|
|
|
|
Any development environment that is not a native development
|
|
environment is refered to as a "cross" development environment.
|
|
There are many different types of cross development environments
|
|
but most fall into one of FIXME basic categories.
|
|
|
|
|
|
Emulation Environments:
|
|
|
|
The first category of cross development environment is called
|
|
"emulation". There are two primary types of emulation, but both
|
|
types result in programs that run on the native host.
|
|
|
|
The first type is "software emulation". This form of cross
|
|
development environment involves a native program that when run on
|
|
the native host, is capable of interpreting, and in most aspects
|
|
running, a program intended for some other machine. This
|
|
technique is typically used when the other machine is either too
|
|
expensive, too slow, too fast, or not available, perhaps because
|
|
it hasn't yet been built. The native, interpreting program is
|
|
called a "software emulator".
|
|
|
|
The GNU Development Tools do not currently include any software
|
|
emulators. Some do exist and the GNU Development Tools can be
|
|
configured to create simple cross development environments for
|
|
with these emulators. More on this later.
|
|
|
|
The second type of emulation is when source intended for some
|
|
other development environment is built into a program intended for
|
|
the native host. The concept of universes in operating systems
|
|
and hosted operating systems are two such development
|
|
environments.
|
|
|
|
The Cygnus Support Release of the GNU Development Tools can be
|
|
configured for one such emulation at this time.
|
|
|
|
./configure sun4 +ansi
|
|
|
|
will configure the source such that when built in a sun4
|
|
development environment the resulting development environment is
|
|
capable of building sun4 programs from strictly conforming ANSI
|
|
X3J11 C source. Remember that the environment used to build the
|
|
tools determines the machine on which this tools will run, so the
|
|
resulting programs aren't necessarily intended to run on a sun4,
|
|
although they usually are. Also note that the source for the GNU
|
|
tools is not strictly conforming ANSI source so this configuration
|
|
cannot be used to bootstrap the GNU tools.
|
|
|
|
|
|
Simple Cross Environments:
|
|
|
|
./configure sun4 +target=a29k
|
|
|
|
will configure the tools such that when compiled in a sun4
|
|
development environment the resulting development environment can
|
|
be used to create programs intended for an a29k. Again, this does
|
|
not necessarily mean that the new development environment can be
|
|
run on a sun4. That would depend on the development environment
|
|
used to build these tools.
|
|
|
|
Earlier you saw how to configure the tools to build a native
|
|
development environment, that is, a development environment that
|
|
runs on your sun4 and builds programs for your sun4. Let's
|
|
pretend that you use stage3 to build this simple cross
|
|
configuration and let's call the new development environment
|
|
gcc-a29k. Remember that this is a native build. Gcc-a29k is a
|
|
collection of native programs intended to run on your sun4.
|
|
That's what stage3 builds, programs for your sun4. Gcc-a29k
|
|
represents an a29k development environment that builds programs
|
|
intended to run on an a29k. But, remember, gcc-a29k runs on your
|
|
sun4. Programs built with gcc-a29k will run on your sun4 only
|
|
with the help of an appropriate software emulator.
|
|
|
|
Building gcc-a29k is also a bootstrap but of a slightly different
|
|
sort. We call gcc-a29k a simple cross environment and using
|
|
gcc-a29k to build a program intended for a29k is called "crossing
|
|
to" a29k. Simple cross environments are the second category of
|
|
cross development environments.
|
|
|
|
|
|
Crossing Into Targets:
|
|
|
|
./configure a29k +target=a29k
|
|
|
|
will configure the tools such that when compiled in an a29k
|
|
development environment, the resulting development environment can
|
|
be used to create programs intended for an a29k. Again, this does
|
|
not necessarily mean that the new development environment can be
|
|
run on an a29k. That would depend on the development environment
|
|
used to build these tools.
|
|
|
|
If you've been following along this walk through, then you've
|
|
already built an a29k environment, namely gcc-a29k. Let's pretend
|
|
you use gcc-a29k to build the current configuration.
|
|
|
|
Gcc-a29k builds programs intended for the a29k so the new
|
|
development environment will be intended for use on an a29k. That
|
|
is, this new gcc consists of programs that are foreign to your
|
|
sun4. They cannot be run on your sun4.
|
|
|
|
The process of building this configuration is another a bootstrap.
|
|
This bootstrap is also a cross to a29k. Because this type of
|
|
build is both a bootstrap and a cross to a29k, it is sometimes
|
|
referred to as a "cross into" a29k. This new development
|
|
environment isn't really a cross development environment at all.
|
|
It is intended to run on an a29k to produce programs for an a29k.
|
|
You'll remember that this makes it, by definition, an a29k native
|
|
compiler. "Crossing into" has been introduced here not because it
|
|
is a type of cross development environment, but because it is
|
|
frequently confused one. The process is "a cross" but the
|
|
resulting development environment is a native development
|
|
environment.
|
|
|
|
You could not have built this configuration with stage3, because
|
|
stage3 doesn't provide an a29k environment. Instead it provides a
|
|
sun4 environment.
|
|
|
|
If you happen to have an a29k lying around, you could now use
|
|
this fresh development environment on the a29k to three-stage
|
|
these tools all over again. This process would look just like it
|
|
did when we built the native sun4 development environment because
|
|
we would be building another native development environment, this
|
|
one on a29k.
|
|
|
|
|
|
The Three Party Cross:
|
|
|
|
So far you've seen that our development environment source must be
|
|
configured for a specific host and for a specific target. You've
|
|
also seen that the resulting development environment depends on
|
|
the development environment used in the build process.
|
|
|
|
When all four match identically, that is, the configured host, the
|
|
configured target, the environment presented by the development
|
|
environment used in the build, and the machine on which the
|
|
resulting development environment is intended to run, then the new
|
|
development environment will be a native development environment.
|
|
|
|
When all four match except the configured host, then we can assume
|
|
that the development environment used in the build is some form of
|
|
library emulation.
|
|
|
|
When all four match except for the configured target, then the
|
|
resulting development environment will be a simple cross
|
|
development environment.
|
|
|
|
When all four match except for the host on which the development
|
|
environment used in the build runs, the build process is a "cross
|
|
into" and the resulting development environment will be native to
|
|
some other machine.
|
|
|
|
Most of the other permutations do exist in some form, but only one
|
|
more is interesting to the current discussion.
|
|
|
|
./configure a29k +target=sun3
|
|
|
|
will configure the tools such that when compiled in an a29k
|
|
development environment, the resulting development environment can
|
|
be used to create programs intended for a sun3. Again, this does
|
|
not necessarily mean that the new development environment can be
|
|
run on an a29k. That would depend on the development environment
|
|
used to build these tools.
|
|
|
|
If you are still following along, then you have two a29k
|
|
development environments, the native development environment that
|
|
runs on a29k, and the simple cross that runs on your sun4. If you
|
|
use the a29k native development environment on the a29k, you will
|
|
be doing the same thing we did a while back, namely building a
|
|
simple cross from a29k to sun3. Let's pretend that instead, you
|
|
use gcc-a29k, the simple cross development environment that runs
|
|
on sun4 but produces programs for a29k.
|
|
|
|
The resulting development environment will run on a29k because
|
|
that's what gcc-a29k builds, a29k programs. This development
|
|
environment will produce programs for a sun3 because that is how
|
|
it was configured. This means that the resulting development
|
|
environment is a simple cross.
|
|
|
|
There really isn't a common name for this process because very few
|
|
development environments are capable of being configured this
|
|
extensively. For the sake of discussion, let's call this process
|
|
a "three party cross".
|
|
|
|
|
|
FINAL NOTES
|
|
-----------
|
|
|
|
By "configures", I mean that links, Makefile, .gdbinit, and
|
|
config.status are built. Configuration is always done from the source
|
|
directory.
|
|
|
|
* "./configure name" configures this directory, perhaps recursively,
|
|
for a single host+target pair where the host and target are both
|
|
"name". If a previous configuration existed, it will be
|
|
overwritten.
|
|
|
|
* "./configure hostname +target=targetname" configures this directory,
|
|
perhaps recursively, for a single host+target pair where the host is
|
|
hostname and target is targetname. If a previous configuration
|
|
existed, it will be overwritten.
|
|
|
|
* "./configure +forcesubdirs hostname +target=targetname" creates a
|
|
subdirectories Host-hostname and Host-hostname/Target-targetname and
|
|
configures Host-hostname/Target-targetname. For now, makes should
|
|
be done from Host-hostname/Target-targetname. "./configure +f name"
|
|
works as expected. That is, it creates Host-name and
|
|
Host-name/Target-name and configures the latter.
|
|
|
|
|
|
Hacking configurations:
|
|
|
|
The configure scripts essentially do three things, create
|
|
subdirectories if appropriate, build a Makefile, and create links to
|
|
files, all based on and tailored to, a specific host+target pair. The
|
|
scripts also create a .gdbinit if appropriate but this is not
|
|
tailored.
|
|
|
|
The Makefile is created by prepending some variable definitions to a
|
|
Makefile template called Makefile.in and then inserting host and
|
|
target specific Makefile fragments. The variables are set based on
|
|
the chosen host+target pair and build style, that is, if you use
|
|
subdirectories or not. The host and target specific Makefile may or
|
|
may not exist. If fragments
|
|
|
|
* Makefiles can be edited directly, but those changes will eventually
|
|
be lost. Changes intended to be permanent for a specific host
|
|
should be made to the host specific Makefile fragment. This should
|
|
be in ./config/hmake-host if it exists. Changes intended to be
|
|
permanent for a specific target should be made to the target
|
|
specific Makefile fragment. This should be in ./config/tmake-target
|
|
if it exists. Changes intended to be permanent for the directory
|
|
should be made in Makefile.in. To propogate changes to any of
|
|
these, either use "make Makefile" or re-configure from the source
|
|
directory.
|
|
|
|
* configure can be edited directly, but those changes will eventually
|
|
be lost. Changes intended to be permanent for a specific directory
|
|
should be made to configure.in. Changes intended to be permanent
|
|
for all configure scripts should be made to configure.template.
|
|
Propogating changes to configure.in requires the presence of
|
|
configure.template which normally resides in the uppermost directory
|
|
you received. To propogate changes to either configure.template or
|
|
a configure.in, use "configure +template=pathtothetemplate".
|
|
This will configure the configure scripts themselves, recursively if
|
|
appropriate.
|
|
|
|
* "./configure -srcdir=foo" is not supported yet. At the moment, things
|
|
will probably be configured correctly only for leaf directories, and
|
|
even they will not have paths to libraries set properly.
|