6d6b4cedd1
The function cleanupFile should always return a single value (as opposed
to a tuple or list). In addition, if it encounters an error, it is
expected to return a value that evaluates to False. As it stands,
however, it returns (None, None) in certain error cases. Change this
function to return None, in those cases.
We previously saw the following error message, when we tried to run
clean_header.py on a non-existent file.
Traceback (most recent call last):
File "clean_header.py", line 208, in <module>
b.updateGitFiles()
File "utils.py", line 164, in updateGitFiles
self._writeFile(dst)
File "utils.py", line 136, in _writeFile
f.write(self.new_data[dst])
TypeError: expected a string or other character buffer object
Change-Id: I5f717dd1a4388f598f0fd4bfd5e6129017de9095
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|---|---|---|
| .. | ||
| android | ||
| tools | ||
| uapi | ||
| README.md | ||
Bionic Kernel Header Files
Bionic comes with a processed set of all of the uapi Linux kernel headers that can safely be included by userland applications and libraries.
These clean headers are automatically generated by several scripts located
in the tools/ directory. The tools process the original
unmodified kernel headers in order to get rid of many annoying
declarations and constructs that usually result in compilation failure.
The 'clean headers' only contain type and macro definitions, with the exception of a couple static inline functions used for performance reason (e.g. optimized CPU-specific byte-swapping routines).
They can be included from C++, or when compiling code in strict ANSI mode. They can be also included before or after any Bionic C library header.
Description of the directories involved in generating the parsed kernel headers:
-
external/kernel-headers/original/Contains the uapi kernel headers found in the android kernel. Note this also includes the header files that are generated by building the kernel sources. -
bionic/libc/kernel/uapi/Contains the cleaned kernel headers and mirrors the directory structure inexternal/kernel-headers/original/uapi/. -
bionic/libc/kernel/tools/Contains various Python and shell scripts used to get and re-generate the headers.
The tools to get/parse the headers:
-
tools/generate_uapi_headers.shChecks out the android kernel and generates all uapi header files. copies all the changed files into external/kernel-headers. -
tools/clean_header.pyPrints the clean version of a given kernel header. With the -u option, this will also update the corresponding clean header file if its content has changed. You can also process more than one file with -u. -
tools/update_all.pyAutomatically update all clean headers from the content ofexternal/kernel-headers/original/.
How To Update The Headers
IMPORTANT IMPORTANT:
WHEN UPDATING THE HEADERS, ALWAYS CHECK THAT THE NEW CLEAN HEADERS DO NOT BREAK THE KERNEL <-> USER ABI, FOR EXAMPLE BY CHANGING THE SIZE OF A GIVEN TYPE. THIS TASK CANNOT BE EASILY AUTOMATED AT THE MOMENT.
Download the Linux kernel source code:
> mkdir kernel_src
> cd kernel_src
kernel_src> git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
Then checkout the stable tag for the new kernel headers to import:
kernel_src> cd linux-stable
kernel_src/linux-stable> git checkout tags/vXXX
Before running the command to import the headers, make sure that you have done a lunch TARGET. The script uses a variable set by the lunch command to determine which directory to use as the destination directory.
After running lunch, run this command to import the headers into the android source tree:
bionic/libc/kernel/tools/generate_uapi_headers.sh --use-kernel-dir kernel_src
Next, run this command to copy the parsed files to bionic/libc/kernel/uapi:
bionic/libc/kernel/tools/update_all.py
Finally, run this command to regenerate the syscalls list:
bionic/libc/tools/gensyscalls.py
After this, you will need to build/test the tree to make sure that these changes do not introduce any errors.