Feeds

Intel cribbed x86-64 tech 'from AMD documents'

But not 100% compatible with AMD64, says analyst

  • alert
  • submit to reddit

Top three mobile application threats

Intel developed its 64-bit extensions to the 32-bit x86 instruction set by "reading AMD's pre-release documentation", Microprocessor Report analyst Tom Halfhill has claimed.

This exercise in "reverse engineering", he says, has yielded a technology that's almost but not quite fully compatible with AMD's AMD64 architecture, the foundation of the chip company's Athlon 64 and Opteron processor families.

Microprocessor Report has "compared all the new instructions, modified instructions, deleted instructions, and modifications to the register files - including control registers, system registers and registers visible to application programs", Halfhill said. It also compared the memory-addressing schemes and many other architectural features, such as data-addressing modes, context-switching behavior, interrupt handling, and support for existing 16- and 32-bit x86 execution modes.

The upshot? "In every case," he concludes, "we found Intel had patterned its 64-bit x86 architecture after AMD64 in almost every detail."

The differences, however, are still enough to cause problems, albeit "minor" ones, according to Halfhill. He suggests these may be eliminated in future incarnations of Intel's x86-64 technology, and in any case, software can be easily coded to cope with both 64-bit architectures. That's what the OpenBSD folks have done, we understand.

"We've tested the Intel x86 64-bit stuff, and it works for OpenBSD," said one of the OS development team. "But it's nasty, because they left out the NX (non-executable) bit in the page tables." ®

Related Stories

Intel's Barrett hints at 64-bit compatibility glitches
Intel's Xeon Extender promises to enlarge your memory size
Intel to ship 64-bit Pentium in time for Longhorn
Intel unveils 64-bit capable Xeon

Combat fraud and increase customer satisfaction

More from The Register

next story
This time it's 'Personal': new Office 365 sub covers just two devices
Redmond also brings Office into Google's back yard
Kingston DataTraveler MicroDuo: Turn your phone into a 72GB beast
USB-usiness in the front, micro-USB party in the back
AMD's 'Seattle' 64-bit ARM server chips now sampling, set to launch in late 2014
But they won't appear in SeaMicro Fabric Compute Systems anytime soon
Brit boffins use TARDIS to re-route data flows through time and space
'Traffic Assignment and Retiming Dynamics with Inherent Stability' algo can save ISPs big bucks
Microsoft's Nadella: SQL Server 2014 means we're all about data
Adds new big data tools in quest for 'ambient intelligence'
prev story

Whitepapers

Securing web applications made simple and scalable
In this whitepaper learn how automated security testing can provide a simple and scalable way to protect your web applications.
Combat fraud and increase customer satisfaction
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
SANS - Survey on application security programs
In this whitepaper learn about the state of application security programs and practices of 488 surveyed respondents, and discover how mature and effective these programs are.
3 Big data security analytics techniques
Applying these Big Data security analytics techniques can help you make your business safer by detecting attacks early, before significant damage is done.