Re: [RFC PATCH glibc 1/4] glibc: Perform rseq(2) registration at C startup and thread creation (v6)

On Wed, 30 Jan 2019, Mathieu Desnoyers wrote:

#if defined (__NR_rseq) && !defined (RSEQ_SIG)
# error "UAPI headers support rseq system call, but glibc does not define RSEQ_SIG."
#endif

Would that take care of your concerns ?

That would of course need appropriate conditionals based on the most 
recent kernel version for which a given glibc version has been updated, so 
that using new kernel headers with an existing glibc release does not make 
the build fail (cf. the test of syscall-names.list).  And being able to 
write such a test only solves one half of the problem - it needs to be 
easy to determine what value to put in that header in glibc for an 
architecture that's newly gained support in the kernel, *without* needing 
any architecture expertise.

-- 
Joseph S. Myers
joseph@codesourcery.com