SFENCE and peripheral devices

dm71 — Mon, 15 Oct 2007 08:21:27 GMT

Does SFENCE(MFENCE) instruction ensure that preceding memory writes are actually propagated to the system bus, so the writes are visible by bus master peripheral devices? Or does it work in conjunction with MESI protocol and is guaranteed to propagate writes only between CPUs/cores?

Re: SFENCE and peripheral devices

Intel_Software_Netw1 — Tue, 16 Oct 2007 15:36:27 GMT

We forwarded this question to our engineering contacts,one of whomresponded:

sfence does cause the so called "PCI posting" to be flushed to devices. The most common way to force a PCI posting flush is to do an mmio read from the device in question; per the PCI spec this will cause any buffered (posted) data to be flushed first.

Lexi S.

IntelSoftware NetworkSupport

http://www.intel.com/software

topic SFENCE and peripheral devices in Intel® ISA Extensions

SFENCE and peripheral devices

Re: SFENCE and peripheral devices