Intel is disabling TSX in Haswell due to software failures

Subject: General Tech | August 12, 2014 - 01:07 PM |
Tagged: Intel, haswell, tsx, errata

Transactional Synchronization Extensions, aka TSX, are a backwards compatible set of instructions which first appeared in some Haswell chips as a method to improve concurrency and multi-threadedness with as little work for the programmer as possible.  It was intended to improve the scaling of multi-threaded apps running on multi-core processors and has not yet been widely adopted.  The adoption has run into another hurdle, in some cases the use of TSX can cause critical software failures and as a result Intel will be disabling the instruction set via new BIOS/UEFI updates which will be pushed out soon.  If your software uses the new instruction set and you wish it to continue to do so you should avoid updating your motherboard BIOS/UEFI and ask your users to do the same.  You can read more about this bug/errata and other famous problems over at The Tech Report.

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"The TSX instructions built into Intel's Haswell CPU cores haven't become widely used by everyday software just yet, but they promise to make certain types of multithreaded applications run much faster than they can today. Some of the savviest software developers are likely building TSX-enabled software right about now."

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August 12, 2014 | 01:36 PM - Posted by Anonymous (not verified)

This is a HUGE deal. O_O

It speaks to an Intel validation failure, which quite frankly is earth shattering. These guys are supposed to be the best of the best, and nothing like this should ever get by their internal testing and released in the wild.

August 12, 2014 | 03:40 PM - Posted by Jeremy Hellstrom

Not the first time nor the last.  Google Pentium FDIV Bug.

August 12, 2014 | 06:25 PM - Posted by Anonymous (not verified)

how about something a bit newer... like the Sandy Bridge Chipset P/H/Z 67 recall.

August 12, 2014 | 01:40 PM - Posted by Tim Verry

This is good news for Carrizo as I believe the latest leaks had it matched up with Haswell on the instruction set front except for TSX heh. At least it's not a mandatory update and users can still take advantage of it in the apps it does work well with.

August 12, 2014 | 04:13 PM - Posted by Anonymous (not verified)

Oh no! Jeffery come down here, The lock elision has been borked, Oh no! Intel's blaming the little Griffin boy, and they- [cut to superman's fortress of solitude....]

August 14, 2014 | 10:48 PM - Posted by Woof (not verified)

Not surprising at all. Most Haswell Core i5 and i7 desktop parts are still being referenced as 84W when a subsequent specification update has changed TDP to 95W. This happened after the marketing bandwagon trumpeted Haswell's power efficiency as one of its key features. Up until today, I don't know why most references, including Intel's ARK, cite these specific desktop parts as 84W when it is in fact 95W. Sure, the mobile parts may have been more energy efficient but the marketing literature wants you to believe that it is a feature of that generation spanning both the mobile and desktop products. Ever heard of the quote "Haswell is Ivy Bridge plus 10 degrees Celsius"?

And what is up with the woeful heatsink and fan Intel ships with boxed processors? As if using cheap thermal paste on the heat spreader (vs solder previously) and initially lying about the TDP isn't bad enough, Intel had to ship coolers that are so loud and subpar, at least relative to the TDP it is trying to address, that its i5 and i7 processors throttle when under heavy load as die temperatures exceed 95 degrees Celsius. A big aftermarket cooler is almost mandatory if you don't want your processor to fry itself.

Now TSX doesn't work. And what more else could turn out to be broken or buggy down the road? AVX, VT-d, AES? Intel knew that Haswell had so little new features going for it that it had to manufacture a dubious feature list to be able to push it to market. Maybe someone inside thought that no one uses these oh so newfangled features anyway so it's perfectly fine to lie and exaggerate about them, no one will know.

Intel's PR and Marketing are really savvy to the point of being deceptively creative. Behavior consistent with their prior practice of using market dominance to "incentivize" resellers from exclusively selling their chips. If resellers don't toe the line, they do so at the expense of "deep discounts".

I also use Intel stuff but I so painfully hope that Intel had more and better competition in the desktop processor market... They've grown complacent and corrupt from being at the top of their game too long. The Haswell and Broadwell desktop processors have been nothing but forcing desktop and enterprise customers to subsidize the company's efforts at the mobile market.

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