mirror of
https://github.com/genodelabs/genode.git
synced 2024-12-30 02:28:54 +00:00
139 lines
7.2 KiB
Plaintext
139 lines
7.2 KiB
Plaintext
|
|
=================
|
|
Genode tool chain
|
|
=================
|
|
|
|
The Genode OS framework depends on the GNU C++ compiler and tool chain. As
|
|
most GNU compilers shipped with standard Linux distributions include
|
|
distro-specific patches and configurations, these tools do not meet Genode's
|
|
special requirements (e.g., thread-local storage configuration). Therefore,
|
|
there exists a special tool chain adapted to the specific requirements of
|
|
Genode.
|
|
|
|
|
|
Recommended development platform
|
|
################################
|
|
|
|
We currently use [http://www.ubuntu.com/ - Ubuntu] 12.04 LTS on servers and
|
|
client machines. Hence, Genode should always build without trouble on these
|
|
platforms.
|
|
|
|
|
|
Unified tool chain
|
|
##################
|
|
|
|
Starting with Genode version 11.11, there is a unified tool chain for all base
|
|
platforms and supported CPU architectures (x86_32, x86_64, and ARM). For Genode
|
|
development, we highly recommend the use of the official Genode tool chain. It
|
|
can be obtained in two ways: as pre-compiled binaries or manually compiled:
|
|
|
|
:Pre-compiled:
|
|
Our pre-compiled tool chain is runnable on Linux x86_32 and x86_64. The
|
|
archives for both versions will be extracted to '/usr/local/genode-gcc'. To
|
|
extract the archive, use the following command:
|
|
! sudo tar xPfj genode-toolchain-<version>-<arch>.tar.bz2
|
|
The use of the 'P' option ensures that the tool chain will be installed at
|
|
the correct absolute path '/usr/local/genode-gcc' where the build system
|
|
expects it to reside by default.
|
|
[http://sourceforge.net/projects/genode/files/genode-toolchain/ - Download the pre-compiled tool chain...]
|
|
|
|
:Compile from source:
|
|
For those of you who prefer compiling the tool chain from source, we provide
|
|
a tool for downloading, building, and installing the Genode tool chain. You
|
|
find the tool in Genode's source tree at 'tool/tool_chain'. For usage
|
|
instructions, just start the tool without arguments.
|
|
|
|
In both cases, the tool chain will be installed to '/usr/local/genode-gcc'. All
|
|
tools are prefixed with 'genode-x86-' or 'genode-arm-' respectively such that
|
|
it is safe to add the installation directory to our 'PATH' variable (optional).
|
|
The Genode tool chain will be used by the Genode build system by default. If
|
|
you desire to use a different tool chain, create a file called 'tools.conf' in
|
|
the 'etc/' subdirectory of your build directory where you can define the
|
|
tool-chain prefix to be used:
|
|
|
|
! CROSS_DEV_PREFIX = /path/to/your/custom/tool_chain/your-x86-
|
|
|
|
However, we recommend you to stick with the official Genode tool chain. If you
|
|
see a valid reason not to use it, please contact us (e.g., via the mailing
|
|
list).
|
|
|
|
|
|
; XXX The Gentoo Portage overlay must be update to the new tool chain
|
|
;
|
|
;Gentoo Portage overlay
|
|
;######################
|
|
;
|
|
;For Gentoo users, there exist a Portage overlay, which includes the Genode
|
|
;toolchain.
|
|
;
|
|
;:[https://github.com/blitz/blitz-overlay]:
|
|
; Portage overlay for using the Genode tool chain on Gentoo
|
|
;
|
|
;You'll find the toolchain under sys-devel/genode-toolchain.
|
|
|
|
|
|
Background information - Why do we need a special tool chain?
|
|
#############################################################
|
|
|
|
Early on in the genesis of Genode, we introduced a custom tool chain to
|
|
overcome several problems inherent to the use of standard tool chains installed
|
|
on Linux host platforms.
|
|
|
|
First, GCC and binutils versions vary a lot between different Linux systems.
|
|
Testing the Genode code with all those different tool chains and constantly
|
|
adapting the code to the peculiarities of certain tool-chain versions is
|
|
infeasible and annoying. Second, Linux tool chains use certain features that
|
|
stand in the way when building low-level system components. For example, the
|
|
'-fstack-protector' option is enabled by default on some Linux distributions.
|
|
Hence, we have to turn it off when building Genode. However, some tool chains
|
|
lack this option. So the attempt to turn it off produces an error. The most
|
|
important problem with Linux tool chains is the dependency of their respective
|
|
GCC support libraries on the glibc. When not using a Linux glibc, as the case
|
|
with Genode, this leads to manifold problems, most of them subtle and extremely
|
|
hard to debug. For example, the support libraries expect the Linux way of
|
|
implementing thread-local storage (using segment registers on x86_32). This
|
|
code will simply crash on other kernels. Another example is the use of certain
|
|
C-library functions, which are not available on Genode. Hence, Genode provides
|
|
custom implementations of those functions (in the 'cxx' library).
|
|
Unfortunately, the set of functions used varies across tool-chain versions. For
|
|
these reasons, we introduced a custom configured tool chain where we mitigated
|
|
those problems by pinning the tools to certain versions and tweaking the
|
|
compiler configuration to our needs (i.e., preventing the use of Linux TLS).
|
|
|
|
That said, the use a our custom configured tool chain was not free from
|
|
problems either. In particular, the script for creating the tool chain relied
|
|
on a libc being present on the host system. The header files of the libc would
|
|
be used to build the GCC support libraries. This introduced two problems. When
|
|
adding Genode's libc to the picture, which is based on FreeBSD's C library, the
|
|
expectations of the GCC support libraries did not match 100% with the semantics
|
|
implemented by Genode's libc (e.g., the handling of 'errno' differs). The
|
|
second problem is the limitation that the tool chain could only be built for
|
|
the platform that corresponds to the host. For example, on a Linux-x86_32
|
|
system, it was not possible to build a x86_64 or ARM tool chain. For this
|
|
reason we used the ARM tool chains provided by CodeSourcery.
|
|
|
|
With Genode 11.11, we addressed the root of the tool-chain problem by
|
|
completely decoupling the Genode tool chain from the host system that is used
|
|
to build it. The most important step was the removal of GCC's dependency on
|
|
a C library, which is normally needed to build the GCC support libraries. We
|
|
were able to remove the libc dependency by sneaking-in a small custom libc stub
|
|
into the GCC build process. This stub comes in the form of the single header
|
|
file 'tool/libgcc_libc_stub.h' and brings along all type definitions and
|
|
function declarations expected by the support-library code. Furthermore, we
|
|
removed all GNU-specific heuristics from the tool chain. Technically, the
|
|
Genode tool chain is a bare-metal tool chain. But in contrast to existing
|
|
bare-metal tool chains, C++ is fully supported.
|
|
|
|
With the libc dependency out of the way, we are now free to build the tool
|
|
chain for arbitrary architectures, which brings us two immediate benefits. We
|
|
do no longer have to rely on the CodeSourcery tool chain for ARM. There is now
|
|
a 'genode-arm' tool chain using the same compiler configuration as used on x86.
|
|
The second benefit is the use of multiarch libs on the x86 platform. The
|
|
genode-x86 tool chain can be used for both x86_32 and x86_64 as build target,
|
|
the latter being the default.
|
|
|
|
Since we introduced GDB support into Genode, we added GDB in addition to GCC
|
|
and binutils to the Genode tool chain. The version is supposed to match the one
|
|
expected by Genode's GDB facility, avoiding potential problems with mismatching
|
|
protocols between GDB monitor and GDB.
|