Original URL: http://www.theregister.co.uk/2005/09/08/xeon_amd64_fix/
Intel to bring full AMD64-compatibility to Xeon
Exclusive Intel is upgrading its Xeon DP processor line-up to introduce a pair of extra EM64T instructions. The move will finally bring the 64-bit server chips into full compatibility with AMD's AMD64 technology.
The chip giant this week revealed it will update the Xeon DP's core from stepping E-0 to G-1, according to company documents seen by The Register. Intel is clearly getting wise to the extent to which journalists are taking a peek at the files it sends to its customers, and the Xeon notice is short on detail, referring readers to non-disclosure agreement-protected specification information.
It needn't have bothered. The changes it's hiding behind the NDA involve the addition of the LAHF and SAHF instructions, currently missing from EM64T but present in AMD64. Allegedly, that's because AMD added the two instructions to its 64-bit ISA after Intel engineers had used it to produce EM64T.
These two instructions copy content back and forth between the chip's status flags and its AH register.
The fully AMD64-compatible Xeons are due to sample on 17 October, Intel's document reveals, the day on which the chip giant will also ship samples of fully AMD64-compatible Pentium 4 5x1 processors. Indeed, when we reported on the planned update of the P4 5x1 line, we suggested that Intel would next patch the Xeon processors based on the desktop series. P4 6x1 updates seem likely too.
The updated P4s are expected to ship in volume on 14 November, with full Xeon availability following a week later on 28 November. ®