Rich Felker
91d5aa0657
the kernel entry point for syscalls on microblaze nominally saves and restores all registers, and testing on qemu always worked since qemu behaves this way too. however, the real kernel treats r3:r4 as a potential 64-bit return value from the syscall function, and copies both over top of the saved registers before returning to userspace. thus, we need to treat r4 as always-clobbered.
musl libc
musl, pronounced like the word "mussel", is an MIT-licensed
implementation of the standard C library targetting the Linux syscall
API, suitable for use in a wide range of deployment environments. musl
offers efficient static and dynamic linking support, lightweight code
and low runtime overhead, strong fail-safe guarantees under correct
usage, and correctness in the sense of standards conformance and
safety. musl is built on the principle that these goals are best
achieved through simple code that is easy to understand and maintain.
The 1.0 release series for musl features coverage for all interfaces
defined in ISO C99 and POSIX 2008 base, along with a number of
non-standardized interfaces for compatibility with Linux, BSD, and
glibc functionality.
For basic installation instructions, see the included INSTALL file.
Information on full musl-targeted compiler toolchains, system
bootstrapping, and Linux distributions built on musl can be found on
the project website:
http://www.musl-libc.org/