https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=197756
--- Comment #10 from commit-h...@freebsd.org --- A commit references this bug: Author: jhb Date: Wed Apr 15 16:52:36 UTC 2015 New revision: 281560 URL: https://svnweb.freebsd.org/changeset/base/281560 Log: MFC 278325,280866: Revert the IPI startup sequence to match what is described in the Intel Multiprocessor Specification v1.4. The Intel SDM claims that 278325: Revert the IPI startup sequence to match what is described in the Intel Multiprocessor Specification v1.4. The Intel SDM claims that the INIT IPIs here are invalid, but other systems follow the MP spec instead. While here, fix the IPI wait routine to accept a timeout in microseconds instead of a raw spin count, and don't spin forever during AP startup. Instead, panic if a STARTUP IPI is not delivered after 20 us. 280866: Wait 100 microseconds for a local APIC to dispatch each startup-related IPI rather than 20. The MP 1.4 specification states in Appendix B.2: "A period of 20 microseconds should be sufficient for IPI dispatch to complete under normal operating conditions". (Note that this appears to be separate from the 10 millisecond (INIT) and 200 microsecond (STARTUP) waits after the IPIs are dispatched.) The Intel SDM is silent on this issue as far as I can tell. At least some hardware requires 60 microseconds as noted in the PR, so bump this to 100 to be on the safe side. PR: 196542, 197756 Changes: _U stable/10/ stable/10/sys/amd64/amd64/mp_machdep.c stable/10/sys/i386/i386/mp_machdep.c stable/10/sys/x86/x86/local_apic.c -- You are receiving this mail because: You are the assignee for the bug. _______________________________________________ freebsd-bugs@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-bugs To unsubscribe, send any mail to "freebsd-bugs-unsubscr...@freebsd.org"
