Date: Sun, 9 Oct 2016 14:41:21 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: FreeBSD Hackers <freebsd-hackers@FreeBSD.org> Subject: I/O-APIC redirection table on AMD chipsets Message-ID: <95ddd0c4-b001-e15e-75cc-79d69dca0518@FreeBSD.org>
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I just want to share a small discovery. For AMD SB7x0 and SB8x0 southbridges (and maybe the newer chipsets too) the Delivery Mode bits in the IO-APIC redirection table MUST be programmed according to the HyperTransport specification, NOT the APIC specification and chipset documentations. For example, for NMIs the delivery mode has to be set to 3 (011b). BTW, the HyperTransport specification says that the destination ID should be 0xff (broadcast) for the NMI type, but in my tests it can be an individual APIC ID as well. Fixed, Lowest Priority and SMI modes have the same encoding in both specification. That explains why this peculiarity is not well known. Refer to Appendix F.1 of the HyperTransport 3.0 Specification for x86 interrupt delivery modes. -- Andriy Gapon
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