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This directory contains patches of the Codezero kernel that are needed for the
integration with Genode. Furthermore, some patches address issues with recent
tool chains not yet supported by the official Codezero verison.
The GNU assembler of binutils-2.21 complains with an error that was ignored
by previous binutils versions:
"Error: .size expression for ... does not evaluate to a constant"
This error seems to occur if the argument of 'BEGIN_PROC' does not match
the argument of 'END_PROC'. The patch fixes such inconsistencies in the
Codezero expect the tool chain to be used for the kernel to not support
shared libraries. This is the case for Codesourcery's arm-non-eabi
tool chain. Such tool chains use to incorporate both libgcc and libgcc_eh
into the single libgcc.a library. In contrast, for tool chains built with
'--enable-shared', libgcc does not contain the functions of libgcc_eh. Hence,
one symbol called '__aeabi_unwind_cpp_pr0' referenced by libgcc and normally
provided by libgcc_eh remains unresolved. There are two possible solutions
for this problem: We could link libgcc_eh to the 'final.elf' image as
expected by libgcc. However, this way, we will need to implement the
the environment expected by libgcc_eh. For Codezero, this is pointless
because no C++ is used. The second option is to provide a dummy symbol
for '__aeabi_unwind_cpp_pr0' just to make the linker happy. This patch
adds such a dummy symbol to 'loader/main.c'.
The userlibs are build with w/o '-nostdinc'. Consequently, the standard
search paths of the tool chain are used. Because the user land is
normally build with the Codesourcery tool chain 'arm-none-linux-gnueabi',
the complete glibc headers (that come with the tool chain) end up in
the default search path. Coincidentally, the userlibs SConstruct file
misses to supply the Codezero libc headers, which goes undetected because
headers such as 'stdio.h' are silently taken from the tool chain's libc.
This patch supplies Codezero's libc include-search path for building
the userlibs. This enables the userlibs to be built with tool chains
that do not come with a complete libc.
SCons 2.0.1 complains about the 'build_dir' argument being renamed to
'variant_dir'. This patch renames the argument where needed for building
the kernel and the default container.
At some point, Codezero abandoned the facility to define the pager for a
given thread via the exregs system call. Instead, the kernel hard-wires the
creator of the thread as the thread's pager. This is conflicting with
Genode's way of creating and paging threads. On the current version of Genode
for Codezero, all threads are paged by one thread (thread 3 happens to be the
global pager) within core. As a work-around to Codezero's current limitation,
we define thread 3 to be the pager of all threads.
Version 4.6.1 of GCC is more picky about dead code than previous versions and
warns about unused variables. Because Codezero is build with the '-Werror'
flag, these warnings cause the kernel build to fail. The patch fixes those
warnings by removing the variables in question.