Currently, we extract a list of __NR_ macros from the kernel headers and generate SYS_ aliases for them.

This has the effect that the SYS_ variant of new system call #defines becomes available only after glibc is recompiled with an updated kernel-headers package.  This is confusing to developers.

I would prefer if the kernel-headers could generate the SYS_ list instead and activate it if glibc defines a special macro (so that backwards compatibility with older glibc headers is not impacted).  Alternatively, the kernel headers could define a macro which indicates that a file with SYS_ alias #defines is available in a specific location.

I would like to implement this change upstream, but found the build system and the cross-architecture variance a bit confusing.  As far as I can tell, the __NR_ macros are only auto-generated on some architectures.  Help with that would be appreciated.