2018-01-30 03:56:01 +00:00
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# `libucontext`
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`libucontext` is a library which provides the `ucontext.h` C API. Unlike other implementations,
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it faithfully follows the kernel process ABI when doing context swaps.
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Notably, when combined with `gcompat`, it provides a fully compatible implementation of the ucontext
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functions that are ABI compatible with glibc.
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2020-12-06 10:54:19 +00:00
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Since version 0.13, for some architectures, you can deploy to bare metal using newlib via the
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`FREESTANDING=yes` make option. Systems which use a syscall cannot work this way. The table
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below shows which architecture ports have been adapted to build with `FREESTANDING=yes`.
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2018-01-30 03:56:01 +00:00
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## supported architectures
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Adding support for new architectures is easy, but you need to know assembly language to do it.
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2020-12-06 10:54:19 +00:00
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| Architecture | Works on musl | Syscall | Supports FREESTANDING |
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|--------------|---------------|---------|-----------------------|
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2020-12-06 13:50:50 +00:00
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| aarch64 | ✓ | | ✓ |
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2020-12-06 13:42:38 +00:00
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| arm | ✓ | | ✓ |
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2020-12-06 10:54:19 +00:00
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| m68k | ✓ | | ✓ |
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2020-12-06 13:34:22 +00:00
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| mips | ✓ | | ✓ |
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2020-12-06 13:23:56 +00:00
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| mips64 | ✓ | | ✓ |
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2020-12-06 10:54:19 +00:00
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| ppc | ✓ | ✓ | |
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| ppc64 | ✓ | ✓ | |
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2020-12-06 13:08:31 +00:00
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| riscv64 | ✓ | | ✓ |
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2020-12-06 12:36:27 +00:00
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| s390x | ✓ | | ✓ |
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2020-12-06 11:37:19 +00:00
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| x86 | ✓ | | ✓ |
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2020-12-06 10:54:19 +00:00
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| x86_64 | ✓ | | ✓ |
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2018-02-14 03:06:01 +00:00
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## building
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`libucontext` uses a simple makefile build system. You should define `ARCH=` at build time, otherwise
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the build system will attempt to guess using `uname -m`.
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```
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$ make ARCH=x86_64
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$ make ARCH=x86_64 check
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$ make ARCH=x86_64 DESTDIR=out install
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2020-05-18 03:28:21 +00:00
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```
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