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