ARMv8.5 Support Lands In GCC Compiler With Latest Spectre Protection
Written by Michael Larabel in GNU on 12 November 2018 at 03:36 PM EST. Add A Comment
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Landing just in time with the GCC 9 branching being imminent is ARMv8.5-A support in the GNU Compiler Collection's ARM64/AArch64 back-end.

This ARMv8.5-A support is an incremental upgrade over the existing ARMv8 support. The ARMv8.5 additions are similar to what we already saw land for LLVM / Clang.

ARMv8.5 does bring some new features like memory tagging, virtualization enhancements, and other bits for what will in turn appear in ARM SoCs in 2019. Arguably most interesting with ARMv8.5 is their hardware protections to fend off Spectre vulnerabilities.

With today's ARMv8.5 landing there is support for the Speculation Battier Instruction as well as for Execution and Data Prediction Restriction Instructions, exposed via the +sb and +predres options with these features being optional. Support for these security features have already been plumbed into GNU Binutils.

The ARMv8.5 support will be exposed with GCC 9 via the -march=armv8.5-a switch as of this commit.
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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter or contacted via

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