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The reason why the old vDSOs were written in C using inline assembly was purely because they were embedded in the C library directly as static inline functions. This was practical during development, because it meant you could invoke system calls without any library dependencies. The vDSO was simply a copy of these functions. Now that we require the use of the vDSO, there is no longer any need for embedding them in C code directly. Rewriting them in assembly has the advantage that they are closer to ideal (less useless branching, less assumptions about registers remaining unclobbered by the kernel, etc). They are also easier to build, as they no longer depend on the C type information for CloudABI. Obtained from: https://github.com/NuxiNL/cloudabi
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