aac831cafa
Previously we probed for CRC32 instructions by testing if they caused SIGILL. Some have expressed doubts about that technique, the Linux documentation advises not to use it, and it's not exactly beautiful. Now that more operating systems expose CPU features to userspace via the ELF loader in approximately the same way, let's use that instead. This is expected to work on Linux, FreeBSD and recent OpenBSD. OpenBSD/ARM has not been tested and is not present in our build farm, but the API matches FreeBSD. On macOS, compilers use a more recent baseline ISA so the runtime test mechanism isn't reached. (A similar situation is expected for Windows/ARM when that port lands.) On NetBSD, runtime feature probing is lost for armv8-a builds. It looks potentially doable with sysctl following the example of the cpuctl program; patches are welcome. No back-patch for now, since we don't have any evidence of actual breakage from the previous technique. Suggested-by: Bastien Roucariès <rouca@debian.org> Discussion: https://postgr.es/m/4496616.iHFcN1HehY%40portable-bastien
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.