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0 pointsmike_hearn2y ago0 comments

The JVM has worked fine on macOS and Apple Silicon for years. It's not violating W^X. The problem is an undocumented/unannounced and probably unintended change in kernel behavior.

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dylan6042y ago

Shouldn't this help zero in on where the issue is located? If it did not occur in the last released beta but it now exists in the released update, doesn't that significantly reduce the footprint of where to search for changes?

shagie2y ago

From a discussion on it previously : https://news.ycombinator.com/item?id=39741517 by fweimer

> The signal comes from a safe fetch, which is just a read that allows ignoring the fault as if it never happened. Such a signal is deliver synchronously, so the usual restrictions for asynchronous signal handlers do not apply.

> The code in question takes into account that the value read might be garbage. See the big comment here: https://github.com/openjdk/jdk/commit/29397d29baac3b29083b1b...

> On current CPUs and operating systems, this is not an optimization, so the code was removed earlier this year: https://bugs.openjdk.org/browse/JDK-8320317

(there's a lot more comments further down that are worth reading)

It is known where this is causing a problem and the code was removed a few months ago in the code for Java 23.

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