RFR: 8367780: Enable UseAPX on Intel CPUs only when both APX_F and APX_NCI_NDD_NF cpuid features are present [v4]
Srinivas Vamsi Parasa
sparasa at openjdk.org
Wed Sep 17 17:54:49 UTC 2025
> The goal of this PR is to enable APX on Intel CPUs (i.e. enable UseAPX) only when both the APX_F and APX_NCI_NDD_NF cpuid feature flags are present.
>
> As per the latest update to the Intel APX specification (https://www.intel.com/content/www/us/en/content-details/861610/intel-advanced-performance-extensions-intel-apx-architecture-specification.html ), when APX_F is set, processors also provide CPUID leaf 0x29 (APX Advanced Performance Extensions Leaf). Any Intel processor that enumerates APX_F also enumerates APX_NCI_NDD_NF.
>
> This PR enhances the HotSpot x86 CPU feature detection to recognize the APX_NCI_NDD_NF sub-feature of Intel APX and update the enabling logic for UseAPX VM flag.
Srinivas Vamsi Parasa has updated the pull request incrementally with two additional commits since the last revision:
- Update CPUInfoTest.java
- Remove APX_NCI_NDD_NF as an explicit feature
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/27320/files
- new: https://git.openjdk.org/jdk/pull/27320/files/21560d0b..91f589ab
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=27320&range=03
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=27320&range=02-03
Stats: 12 lines in 4 files changed: 0 ins; 8 del; 4 mod
Patch: https://git.openjdk.org/jdk/pull/27320.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/27320/head:pull/27320
PR: https://git.openjdk.org/jdk/pull/27320
More information about the graal-dev
mailing list