From 8118eb4a8682214cc6cc7f85336866929bcd971f Mon Sep 17 00:00:00 2001 From: Antonin Godard Date: Fri, 29 Aug 2025 11:04:04 +0200 Subject: migration-guides/release-notes-5.3.rst: add x86 qemu micro-arch level bump After commit c9585bb8689b ("Revert "qemux86-64: Reduce tuning to core2-64"") in OE-Core, document the QEMU x86 micro-architecture level bump in the release notes for 5.3. Co-authored-by: Alexander Kanavin (From yocto-docs rev: 22c0fc1943c23d6f927034afdfa25ce64c5ba79a) Signed-off-by: Antonin Godard Signed-off-by: Richard Purdie --- documentation/migration-guides/release-notes-5.3.rst | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/documentation/migration-guides/release-notes-5.3.rst b/documentation/migration-guides/release-notes-5.3.rst index f32c6162da..4782c24366 100644 --- a/documentation/migration-guides/release-notes-5.3.rst +++ b/documentation/migration-guides/release-notes-5.3.rst @@ -311,6 +311,25 @@ New Features / Enhancements in |yocto-ver| - Refactor :ref:`ref-classes-qemu` functions into library functions (in :oe_git:`lib/oe/qemu.py `). + - The ``qemux86-64`` :term:`MACHINE` now defaults to the ``x86-64-v3`` + micro-architecture level. + + The previous default was Core 2 era processors. This change means that the + toolchain is configured to build for that level, and QEMU is configured to + emulate it. + + The v3 level adds support for AVX/AVX2/BMI/BMI2/F16C and other newer + instructions which are seeing increasing usage in modern software and add + performance benefits. Please see :wikipedia:`X86-64 Microarchitecture + levels ` for definition of the levels and + lists of Intel/AMD CPUs where support for the instructions was first + added. + + Note that if QEMU system emulation is used on an x86 build machine with + :wikipedia:`KVM ` enabled, then the build + machine's CPU must also be recent enough to support these instructions + natively. + - Documentation changes: - Part of :term:`BitBake` internals are now documented at -- cgit v1.2.3-54-g00ecf