From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Luck, Tony" Date: Wed, 05 Nov 2003 17:00:01 +0000 Subject: RE: [RFC] Better MCA recovery on IPF Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org > I still believe that a failed speculative read (for example > of poisoned data) will generate an MCA. Perhaps someone from > Intel can confirm or deny? It depends on exactly what you mean by "speculative read", and even there it is not architecturally defined, so different implementations may behave differently ("Ask not the elves for advice for they will say both yes and no" - Tolkien). "Speculative" reads from memory as a result of lfetch, or a code fetch for a mispredicted branch that reference poisoned data may not generate an MCA (since the processor can know that the poisoned data will not be consumed. Speculative reads from "ld.s" have less scope to avoid the MCA There's a new bit coming for PAL_PROC_{GET,SET}_FEATURES which will at least tell you (and may allow you to request, if the implementation supports it) whether the processor will respond to poison with CMCI, or upgrade to MCA ... watch the web for a spec update to the SDV -Tony