Well, let's begin
We're going to compile the GlibC, with all internals to make it ready. After you prepare this, you might also check DoomLord's post here (http://forum.xda-developers.com/show....php?t=1041064
) to make a recovery zip to flash this to your device. Make yourself comfortable now; because I'm going to explain everything we use here, thus this might be loong guide
1- Obtain the Sources
First, obtain the sources that you're going to compile. Check all the dependencies of the package and download them (and compile them) before. In our case, since we'll compile GlibC and all it needs is a working toolchain; we don't need to worry about this.
You can obtain GlibC source code from http://ftp.gnu.org/gnu/glibc/
address. Note that, since we're building GlibC for ARM devices and since GlibC seperated ARM support to "Ports" package, we need to download that as well. Make sure you download the same versions of Glibc and Glibc-Ports packages.
2- Extract the Sources, and make a build directory
Extract the sources to some folder; say /home/<user>/Desktop/glibc . Also extract the glibc-ports package to some direcorty, say /home/<user>/Desktop/glibc-ports.
After this, rename the folder "glibc-ports" to just "ports" and then move it inside to the "glibc" folder. If you don't do this step, you'll have "ARM is unsupported" error in configuration step.
Since glibc cannot be compiled from the directory which sources are in it (a restriction made by the developers, to make sources unchanged and ready to be compiled again), we need to make another folder from which we're going to call the compilation tools. Let's say this directory is named as "glibc-build", also at /home/<user>/Desktop .
3- Start "configure"
Now, open a terminal emulator window ( you can use Ctrl+Alt+T keys under Ubuntu to easily open one ). Change into the glibc-build directory.
After this operation, we've to call the glibc's auto-configure script from this folder. Note that ".." is a "special folder name" which denotes the upper level directory (so basicly, we're changing into the upper level in directory tree - Desktop in our case - and then call something from a folder inside that)
When you run the above command, configure will give you the options you can use to configure this package for your needs. Nearly 90% of the time, checking the output of this command gives you the options you need to set to compile properly.
`configure' configures GNU C Library (see version.h) to adapt to many kinds of systems.
Usage: ../glibc-2.14/configure [OPTION]... [VAR=VALUE]...
To assign environment variables (e.g., CC, CFLAGS...), specify them as
VAR=VALUE. See below for descriptions of some of the useful variables.
Defaults for the options are specified in brackets.
-h, --help display this help and exit
--help=short display options specific to this package
--help=recursive display the short help of all the included packages
-V, --version display version information and exit
-q, --quiet, --silent do not print `checking ...' messages
--cache-file=FILE cache test results in FILE [disabled]
-C, --config-cache alias for `--cache-file=config.cache'
-n, --no-create do not create output files
--srcdir=DIR find the sources in DIR [configure dir or `..']
--prefix=PREFIX install architecture-independent files in PREFIX
--exec-prefix=EPREFIX install architecture-dependent files in EPREFIX
By default, `make install' will install all the files in
`/usr/local/bin', `/usr/local/lib' etc. You can specify
an installation prefix other than `/usr/local' using `--prefix',
for instance `--prefix=$HOME'.
For better control, use the options below.
Fine tuning of the installation directories:
--bindir=DIR user executables [EPREFIX/bin]
--sbindir=DIR system admin executables [EPREFIX/sbin]
--libexecdir=DIR program executables [EPREFIX/libexec]
--sysconfdir=DIR read-only single-machine data [PREFIX/etc]
--sharedstatedir=DIR modifiable architecture-independent data [PREFIX/com]
--localstatedir=DIR modifiable single-machine data [PREFIX/var]
--libdir=DIR object code libraries [EPREFIX/lib]
--includedir=DIR C header files [PREFIX/include]
--oldincludedir=DIR C header files for non-gcc [/usr/include]
--datarootdir=DIR read-only arch.-independent data root [PREFIX/share]
--datadir=DIR read-only architecture-independent data [DATAROOTDIR]
--infodir=DIR info documentation [DATAROOTDIR/info]
--localedir=DIR locale-dependent data [DATAROOTDIR/locale]
--mandir=DIR man documentation [DATAROOTDIR/man]
--docdir=DIR documentation root [DATAROOTDIR/doc/c-library]
--htmldir=DIR html documentation [DOCDIR]
--dvidir=DIR dvi documentation [DOCDIR]
--pdfdir=DIR pdf documentation [DOCDIR]
--psdir=DIR ps documentation [DOCDIR]
--build=BUILD configure for building on BUILD [guessed]
--host=HOST cross-compile to build programs to run on HOST [BUILD]
--disable-option-checking ignore unrecognized --enable/--with options
--disable-FEATURE do not include FEATURE (same as --enable-FEATURE=no)
--enable-FEATURE[=ARG] include FEATURE [ARG=yes]
--disable-sanity-checks really do not use threads (should not be used except
in special situations) [default=yes]
--enable-check-abi do "make check-abi" in "make check" (no/warn/yes)
--enable-shared build shared library [default=yes if GNU ld & ELF]
--enable-profile build profiled library [default=no]
--enable-omitfp build undebuggable optimized library [default=no]
--enable-bounded build with runtime bounds checking [default=no]
--disable-versioning do not include versioning information in the library
objects [default=yes if supported]
--enable-oldest-abi=ABI configure the oldest ABI supported [e.g. 2.2]
initialize __stack_chk_guard canary with a random
number at program start
configure and build add-ons in DIR1,DIR2,... search
for add-ons if no parameter given
--disable-hidden-plt do not hide internal function calls to avoid PLT
--enable-bind-now disable lazy relocations in DSOs
--enable-static-nss build static NSS modules [default=no]
--disable-force-install don't force installation of files from this package,
even if they are older than the installed files
--enable-kernel=VERSION compile for compatibility with kernel not older than
--enable-all-warnings enable all useful warnings gcc can issue
--enable-multi-arch enable single DSO with optimizations for multiple
enable experimental malloc features
--enable-nss-crypt enable libcrypt to use nss
--with-PACKAGE[=ARG] use PACKAGE [ARG=yes]
--without-PACKAGE do not use PACKAGE (same as --with-PACKAGE=no)
--with-gd=DIR find libgd include dir and library with prefix DIR
--with-gd-include=DIR find libgd include files in DIR
--with-gd-lib=DIR find libgd library files in DIR
--with-fp if using floating-point hardware [default=yes]
--with-binutils=PATH specify location of binutils (as and ld)
--with-elf if using the ELF object format
--with-selinux if building with SELinux support
--with-xcoff if using the XCOFF object format
--without-cvs if CVS should not be used
--with-headers=PATH location of system headers to use (for example
/usr/src/linux/include) [default=compiler default]
--with-tls enable support for TLS
--without-__thread do not use TLS features even when supporting them
--with-cpu=CPU select code for CPU variant
Some influential environment variables:
CC C compiler command
CFLAGS C compiler flags
LDFLAGS linker flags, e.g. -L<lib dir> if you have libraries in a
nonstandard directory <lib dir>
LIBS libraries to pass to the linker, e.g. -l<library>
CPPFLAGS (Objective) C/C++ preprocessor flags, e.g. -I<include dir> if
you have headers in a nonstandard directory <include dir>
CPP C preprocessor
CXX C++ compiler command
CXXFLAGS C++ compiler flags
Use these variables to override the choices made by `configure' or to help
it to find libraries and programs with nonstandard names/locations.
Report bugs to <glibc>.
GNU C Library home page: <http://www.gnu.org/software/c-library/>.
General help using GNU software: <http://www.gnu.org/gethelp/>.
The help is quite straightforward, and all explanations are already done. The most important options for our case here is "prefix" and "host". Also, for compilation of GlibC, we need to give "with-headers", "with-tls" and "with-ports" proper values.
"Prefix" is a very important option. This options specifies where the installed binaries and libraries "think" they are. Some binaries and libs. are quite flexible: they don't care about where they are, thus the value of prefix isn't much of importance, but most of the time, it is. Omitting a prefix value here will make PREFIX value of "/usr/local" - which is quite dangerous because it may screw your own system (/usr/local is usually where your own PC applications are - most probably you cannot screw this folder if you're not a super-user but, well, anyway...); so always change this value to something proper when you're cross compiling.
Also, make sure that this path exists in your target device. If you set a prefix, say /cache, and then copy the stuff at, say, /data; it's highly probable that your applications will search for it's config files at /cache, and will complain that they are not found - since they're at /data. Since AFAIK, there is no way to change this in most application after compilation of software, you have to recompile the program to fix such errors (or move the application to the prefix it's set).
I usually use /data as prefix, because I install the stuff to there.
Host is another very important option. If you don't give this parameter, auto-configure will think you're compiling this application for the PC you're using. We've to give "host" the machine specification we're compiling the app for. For ARM based devices, this is mostly something line "arm-xxx-linux" or "arm-linux" or "arm-xxxx-linux-gnueabi" or such.
How do you found this out? Well, simple: If you followed my crostool-ng tutorial and used the same options as I did; your host name will be in "arm-xxxxxx-linux-gnueabi" format. "xxxxx" here is what your vendor name is. If you set a vendor value when making the toolchain, you must write it here. If you left it empty, xxxxx will be "unknown".
The other way to check this is your toolchain's name of gcc command: If your ARM GCC toolchain name is "arm-myvendor-linux-gnueabi-gcc" then, your host name is "arm-myvendor-linux-gnueabi".
Most of the times, there are other options that you must give. As for an example, here is what I generally use to compile glibC:
../glibc-2.14/configure --host=arm-msm-linux-gnueabi --prefix=/data --with-tls --with-ports="nptl, ports"
I use host as "arm-msm-linux-gnueabi" because this is my cross compile target name.
We set "with-tls" option here: it's for GlibC to support Thread Local Storage. This is a programming scheme that allows threads to have their own storage area; and we give this configuration here to give GlibC a support for this. More info about TLS can be found online in programming wiki's.
We also set "with-ports" because we're also installing some extra plugins for our GlibC install. NPTL is an advanced threading library that supports many advanced features like TLS and such. There is also a "linuxthreads" but it's older. New versions of GlibC is not shipped with "linuxthreads" either. The other port, "ports" is for ARM support.
You must also give the kernel source directory here with a parameter of "with-headers" if you're using some other toolchain and your kernel sources are in some other place. Thanks to crostool-ng that it moves all the headers to the toolchain folder and makes them automatically reachable, so you can omit this parameter.
Well, when you give the command and supply the options and press ENTER, it shall start configuring the package:
When there is a missing dependency or option, it shall generally give you a warning at this step and terminate the configuration. You must then find the solution of this error (install the necessary dependency etc.) and then try to configure the package again - as I said, this is usually not the case for GlibC
3- Start "make"
After configuration process is done without errors, you can pass to the compilation phase. If you did configuration properly, you don't have to use special parameters and such for most packages. Just issue the command "make" and wait
Once this is completed without errors, you're nearly ready for the shipment
Note that, if you get any errors in this process, you should definitely google it; since errors in this level is quite application and build environment (your machines configs. etc.) specific. The errors in this phase is usually needs some tricks to fix, and they are usually not so easy to fix
3- Start "make install"
Once the compilation is successful, you can install the application to the "PREFIX" folder you specified whilst configuring the package. In order to do that, just issue:
However, issuing just this command isn't what we want generally: Since we've cross compiled the application, we're not interested in installing that to our PC! We want it to be somewhere we can easily access, so that we can distribute easily right?
For most packages, three important variables are necessary to make this. Which variable is heeded is highly dependent of package, however it's DESTDIR usually used.
DESTDIR: The variable usually used in makefiles. When you set DESTDIR while giving "make install", the application becomes installed to DESTDIR/PREFIX folder, instead of just PREFIX folder without changing the prefix info inside the application
so it makes it easier for us to distribute the package.
install_root : GlibC uses this variable, instead of DESTDIR. I didn't see any other packages using this.
INSTALL_TOP: OpenSSL and Lua packages use this variable instead of DESTDIR.
Which of these variable is used cannot be identified either without examining the Makefile, or without testing it
How are you going to give it a value? Simple: you just assign the variable a value, after giving "make install" command:
make install DESTDIR=/home/<user>/myapp
For GlibC, this becomes:
make install install_root=/home/<user>/glibc
Which makes glibc installed to /home/<user>/glibc folder.
You can take the files from this folder and make a flashable zip; and send it to your device!
- Be careful about the PREFIX value, you should install the files to this place in your device as well.
- Most of the times, you don't need the "include" folder - this folder keeps the header files for your packages, so that other applications may be compiled with them. Since we're not compiling applications in our device, we don't need headers. Compiled applications don't use headers anymore.
- Most of the times, .a files under the "lib" folder is unnecessary - these are static libraries that are usually used when applications are being compiled. Since we don't compile stuff at our device, we don't need them - they are usually quite big too! Be careful though: some packages don't offer .so files (which are dynamic libraries for applications to use dynamically) - it might be necessary to keep .a files then.
- .la files are needed for application compilation with libraries, you can erase them as well.
- pkgconfig can be erased in distribution packages. PKGConfig is a tool for compilation that automatically parses the files in pkgconfig dirs to give necessary compilation parameters with dynamic libraries to the applications at compile time. Like we don't need headers, we don't need those files.
Well, that's it. I hope I could be of some help. See you next time and happy Android'ing!