Messages in this thread | | | Date | Thu, 20 Sep 2018 20:20:28 +0000 | From | Joseph Myers <> | Subject | Re: [RFC PATCH] glibc: Perform rseq(2) registration at nptl init and thread creation |
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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@codesourcery.com
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