On Thu, 20 Sep 2018, Mathieu Desnoyers wrote: > Are you saying glibc has an explicit check for the kernel version visible > from /proc before using specific features ? If so, how can this work with > the variety of feature backports we find in the distribution kernels out > there ? See sysdeps/unix/sysv/linux/dl-sysdep.c and sysdeps/unix/sysv/linux/dl-osinfo.h. As I said, Carlos has proposed removing that check. > For too-old headers at compile time, one possibility is that we don't event > expose the __rseq_abi TLS symbol. OTOH, if we need to keep exposing it anyway > for ABI consistency purposes, then we'd leave its cpu_id field at the initial > value (-1). But that would require that we copy linux/rseq.h into the glibc > source tree. The ABI needs to be independent of the kernel headers used. I don't think you need to copy linux/rseq.h; all you should need is to e.g. define an array of suitable size and alignment with the relevant member initialized and a suitable explanatory comment. -- Joseph S. Myers joseph@xxxxxxxxxxxxxxxx
