REOPENED307825
[WTF] Support creating `WTF::Thread`s with a preallocated deferred-stack on ARM64E 
https://bugs.webkit.org/show_bug.cgi?id=307825
Summary [WTF] Support creating `WTF::Thread`s with a preallocated deferred-stack on A...
Marcus Plutowski
Reported 2026-02-13 11:08:58 PST
rdar://170333133 In order to implement rdar://134795676, we need to be able to start a WTF::Thread on one stack A, then, during initialization, switch to another stack B through a trampoline. This is because stack B will eventually have special memory protections (via os_thread_self_restrict_...), which would cause us to fault during pthread_create, as the OS does not know to correctly empower the thread to as part of thread-creation — so we need to do so ourselves, which means we need to be able to run on a ‘normal’ stack for at least a frame or two while we do so.
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Marcus Plutowski
Comment 1 2026-02-13 11:16:13 PST
Pull request: https://github.com/WebKit/WebKit/pull/58644
EWS
Comment 2 2026-02-16 16:44:00 PST
Committed 307676@main (6d5322b005e5): <https://commits.webkit.org/307676@main> Reviewed commits have been landed. Closing PR #58644 and removing active labels.
WebKit Commit Bot
Comment 3 2026-02-16 20:32:20 PST
Re-opened since this is blocked by bug 308028
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