55 lines
2.0 KiB
Plaintext
55 lines
2.0 KiB
Plaintext
Welcome to Bionic, Android's small and custom C library for the Android
|
|
platform.
|
|
|
|
Bionic is mainly a port of the BSD C library to our Linux kernel with the
|
|
following additions/changes:
|
|
|
|
- no support for locales
|
|
- no support for wide chars (i.e. multi-byte characters)
|
|
- its own smallish implementation of pthreads based on Linux futexes
|
|
- support for x86, ARM and ARM thumb CPU instruction sets and kernel interfaces
|
|
|
|
Bionic is released under the standard 3-clause BSD License
|
|
|
|
Bionic doesn't want to implement all features of a traditional C library, we only
|
|
add features to it as we need them, and we try to keep things as simple and small
|
|
as possible. Our goal is not to support scaling to thousands of concurrent threads
|
|
on multi-processors machines; we're running this on cell-phones, damnit !!
|
|
|
|
Note that Bionic doesn't provide a libthread_db or a libm implementation.
|
|
|
|
|
|
Adding new syscalls:
|
|
====================
|
|
|
|
Bionic provides the gensyscalls.py Python script to automatically generate syscall
|
|
stubs from the list defined in the file SYSCALLS.TXT. You can thus add a new syscall
|
|
by doing the following:
|
|
|
|
- edit SYSCALLS.TXT
|
|
- add a new line describing your syscall, it should look like:
|
|
|
|
return_type syscall_name(parameters) syscall_number
|
|
|
|
- in the event where you want to differentiate the syscall function from its entry name,
|
|
use the alternate:
|
|
|
|
return_type funcname:syscall_name(parameters) syscall_number
|
|
|
|
- additionally, if the syscall number is different between ARM and x86, use:
|
|
|
|
return_type funcname[:syscall_name](parameters) arm_number,x86_number
|
|
|
|
- a syscall number can be -1 to indicate that the syscall is not implemented on
|
|
a given platform, for example:
|
|
|
|
void __set_tls(void*) arm_number,-1
|
|
|
|
|
|
the comments in SYSCALLS.TXT contain more information about the line format
|
|
|
|
You can also use the 'checksyscalls.py' script to check that all the syscall
|
|
numbers you entered are correct. It does so by looking at the values defined in
|
|
your Linux kernel headers. The script indicates where the values are incorrect
|
|
and what is expected instead.
|