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Boffins offer to make speculative execution great again with Spectre-Meltdown CPU fix

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Linux

Hard as I try...

I can't picture chipmakers fixing these vulns in hardware and comercialising the new chips in less than two years. The amount of work involved in updating the designs for most of their market niches has to be a humongous nightmare! 8^(

I'm curious about whether it'd be possible to create a Linux version that can't be affected by these exploits, if neccesary with the help of new programming tools and mandatory programming standards.

This situation has a good chance of turning hundreds of millions of old(ish) PCs into linux stations.

PD: We definitely need a Keep-On-Dreaming Icon! 8^)

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Re: Hard as I try...

> and mandatory programming standards

There's your problem right there.

If you criminalise side channel attacks then only criminals will have side channel attacks.

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Re: Hard as I try...

I'd like to believe that 1) SafeSpec is actually viable (in terms of die space and performance cost) and that 2) CPU vendors will actually spend money implementing it. But I try not to be too optimistic ...

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Re: Hard as I try...

and mandatory programming standards

There's your problem right there.

The problem is the "need for speed" and the fact the world+dog now expects to run javascript in web browsers. So the malicious code comes from any web site that is vaguely compromised (such as advert channels) and that today is "normal". Web browsers can (and partly may do) things to disrupt timing which is the underlying exploit route, but I doubt they are willing to break stuff that is already out there to shore up hardware design flaws.

Most likely their core developer efforts are about removing useful browser functions (firefox) or adding spying (chrome) instead, but then I'm a cynical bastard at heart.

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Stop

Re: Hard as I try...

mandatory programming standards? who would enforce it? what's the punishment for violating it, 'whack my pee pee' or 'take away my birthday' ???

last thing we need is MORE regulations on software. say buh-bye to open source if that ever starts, because once gummint gets its grimy paws on something, it NEVER! LETS! GO!!!

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Devil

Re: Hard as I try...

"SafeSpec is actually viable"

At least one person proposed something even simpler, in essence saving the speculative state along with thread/task state, and restoring it on thread/task switch. That way it wouldn't really be possible to have "the same speculative state" across thread/task switches. Couple that with actual security tests on speculative memory access [at the time of access, not 'some amount of time after you did it'], and the leaks SHOULD be plugged.

you wouldn't need any 'shadow states' or anything like that. Just normal task state stuff inside the kernel would do. And if you don't want anybody accessing that info, you DO! NOT! MAP! IT! INTO! USER! SPACE!!!

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Re: Hard as I try...

The best defense against bad guys with side channel attacks are obviously good guys with side channel attacks. That is of course what National Sidechannel Association (better known as NSA) want me to believe.

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Re: Hard as I try... (@ GrumpyOldBloke)

No need to criminalize anything. You make compilers that create only safe code -in the context of the discussed processor bugs-. and somehow force the OS to accept only executables created using these tools. the progamming standards just provides a list of things that safe executables can and can not do, and the compilers&such enforce said rules. The las step consists on the Hypothetical OS checking that the executables have been developed using these tools, probably by using some crypto-negotiation and similar dark magicks.

Does this make sense? Honest question.

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Anonymous Coward

Re: Hard as I try... (@ GrumpyOldBloke)

I've no idea if it needs crypto singing. I don't "know" that my HTTPS connection is really HTTPS, it could be Google and chrome are pretending, and just displaying an entirely fake website, the OS and PC built and distributed by the CIA to "catch me"... however I assume the system is programed and working as intended, with no lizard people.

Same goes for the water. I don't test it for lead and poison, my house does not test it. The community/society/industry does. I don't have the ability to test every drop of water.

So providing the community start using these tools, we can presume bank that says their online banking is "programed with spectre safe calls/registers/etc" is programed that way. As with the HTTPS standard, those saying they have it implemented, but don't actually implement it (we have all seen .jpg icons on websites that don't implement those standards, would be detected by these researchers. (Just as a fake browser would soon become evident it's not really doing HTTPS, as sites that require it would refuse connection, and the user would investigate why). But I agree, hopefully in time, the OS can detect if the app is "secure" or not. But the OS cannot know if the user wants "secure" or not (how does it know it's a password store or a game character gold points store?).

If companies don't start using these mitigations, users (professional code divers or not) will start to notice data/passwords getting "lots" more often than those that do!

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Anonymous Coward

Re: Hard as I try... (@ GrumpyOldBloke)

No. Adding more lock-in crap is not the way. It's already bad enough with uefi and "secure boot". That is, unless you actually want to relinquish the ability to run whatever the hell you want, and enthrall yourself to corporate whims.

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Re: Hard as I try... (@ GrumpyOldBloke)

"Does this make sense? Honest question." - nope. The compilers are not at fault, although they may help alleviate the pain. It is multistage pipelines in the CPU and the associated high cost of branch misprediction which pushed the CPU designers to speculatively execute branches before we know whether or not we need it. Couple this with the high cost of cache misses and that's your side channel attach right there.

One way to fix it would be to push the "speculative" part from the CPU to the compiler like Mill architecture does, but it is a very different beast to what we have now, with a very different instruction set to match.

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Big Brother

Re: Hard as I try...

If you criminalise side channel attacks then only criminals will have side channel attacks.

That's not what is being said.

What is being said is that the code should follow certain guidelines so that risks regarding certain side-channel are mitigated in released tarballs (same as no code should be released that doesn't have a pretty good guarantee that buffer overflows can't happen, because it's 2018)

I mean, who would think of criminalizing side-channel attacks? That would be like saying security research is illegal, or allowing patenting some obscure mathematical theorem. Who could be that retarded and in thrall to special interests?

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Re: Hard as I try...

One solution is to make high precision timers inaccessible to JavaScript. All these side channels go away if your timer only has multi-microsecond resolution.

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Re: Hard as I try...

"I'm curious about whether it'd be possible to create a Linux version that can't be affected by these exploits"

Yes and No. There already are Windows, Linux etc versions not affected by these exploits, and that is done by canning speculative execution and losing performance. As I understand the issue, a Linux (or any OS) version that is not affected AND still runs speculative execution (and therefore full performance) is not possible, since it's a hardware issue.

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Re: Hard as I try...

One solution is to make high precision timers inaccessible to JavaScript. All these side channels go away if your timer only has multi-microsecond resolution.

Or to just wonder how, and why, an interpreted language that is designed to execute within any compliant webbrowser, on any Operating System, on any hardware/virtual architecture can somehow access the low level CPU state.

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Re: Hard as I try...

I'm not up with the latest features of the latest x86 CPUs but common sense would indicate that there should be instructions that will flush the hardware executable environment, including the pipeline and speculative caches.

In this case the task/process manager of the operating system could ensure that such flushes are performed however the more rapidly that processes are switched between (to give the illusion of parallel execution) the more such a change would affect the performance of the system.

Any thorough solution is likely to require both hardware and software changes, with a certain level of fallback capability within the hardware to cover non-supporting operating systems.

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Re: Hard as I try... (@ GrumpyOldBloke)

...and somehow force the OS to...

I love when people propose a "solution" and use the word "somehow" in it.

It's like "we've totally got this flying car sorted out - we just need to somehow develop an antigravity paint, and some way of stopping people crashing into each other..."

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Re: Hard as I try...

"It's already bad enough with uefi and "secure boot"."

UEFI is just a modern replacement for a BIOS, you might as well complain about SATA and PCIe.

Secure boot is just a method of checking that your bootloader has not been tampered with.

What's the problem?

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Anonymous Coward

It's time to remove "Speculation" from CPUs

Back in 1996 when the Pentium 1 with 200 MHz was modern, we had no such thing as "Speculation" inside the CPU.

Then came the Pentium Pro and Pentium II and introduced flacky "Speculation" to improve speed on behalf of security.

So let's go back to No-Speculation inside CPU. It's not the first time, Intel had to abandon a CPU architecture and go back to decade old CPU. Pentium 4 was a dead-end and they went back to the Pentium Pro architecture that powered also Pentium II and Pentium III, as well as Pentium M (the Pentium III for Notebooks) and then later again served as Core, Core2Duo, Core5/7. And Intel went back to Pentium I architecture for the first Atom series (2008). Ironically, it's the only "modern" Intel CPU that isn't defected and vulnerable to Meltdown and Spectre, yet has HyperThreading and 1.4 GHz performance and runs Win7/2008R2 without any issues at all.

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Re: Hard as I try...

At least one person proposed something even simpler, in essence saving the speculative state along with thread/task state, and restoring it on thread/task switch.

I'm curious why you think this would close the cache timing channel. Or indeed most other side channels.

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Re: Hard as I try...

One solution is to make high precision timers inaccessible to JavaScript.

There are many alternate timing mechanisms. I've posted the link to the paper in Reg discussions of Spectre-class attacks before.

Or to just wonder how, and why, an interpreted language that is designed to execute within any compliant webbrowser, on any Operating System, on any hardware/virtual architecture can somehow access the low level CPU state.

Why do you think it needs to? The original Javascript Spectre attacks did not "access the low level CPU state".

The various Spectre variants are well-documented and described in detail in many places. It's not hard to learn how they work, or why bumper-sticker solutions don't significantly reduce the class of side-channel attacks.

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Re: It's time to remove "Speculation" from CPUs

Back in 1996 when the Pentium 1 with 200 MHz was modern, we had no such thing as "Speculation" inside the CPU.

Perhaps you didn't. Plenty of us did.

Then came the Pentium Pro and Pentium II and introduced flacky "Speculation" to improve speed on behalf of security.

The PPro and P2 did not invent speculation. And it is probably not "flacky", though it's hard to say, since that appears to be your personal coinage.

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Re: Hard as I try...

> what's the punishment for violating it

Torvalds will swear at you!

> 'whack my pee pee'

Don't piss him off *too* much...

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Devil

I'd like to add that...

... another effect would be millions of PCs freed of Windows 10 OSmalware. What's there not to like?

Farewell, WIntel, it was nice while it lasted. Don't let the door hit your etc etc ...

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Re: I'd like to add that...

Where are you gonna go, then? Most of the other architectures suffer from variants of this, too, including ARM. The few that don't are basically too simple for practical applications these days.

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Re: I'd like to add that...

Hindows10 my friend :)

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To Stop Futures and Derivative Plays as Presently Planned for the Past ..... Believe in Miracles

What hardware/chipsets/Intel type operations, and Supporting Software Programming too for that matter, all appear to be doing, is vain and unnecessarily self-destructive and catastrophically revealing battle against a Not Dysfunctional Almighty Imagination Pentesting Universal Interfaces and Users Intelligence, with such a proposed Secure Siloing of Rogue and/or Random and Renegade Speculation/Advanced Physical Plans, in the likes of something which is not yet realised to be extraordinarily rendered as no better than a colander leaking remote virtual operation to Greater Forces with Alienating Sources.

Is the Past to be Present in your Future Plan and Greater IntelAIgent Games Play? Or are you Free of and Released from that Prison to Travel to Brave New More Orderly Newsed Worlds?

There's a lot more going on out there in the Realms of CyberSpace, El Reg, than just the little that has the Status Quo terrifying and terrorising itself with the actions and plans of A.N.Others to justify the Daily Zeroday News as delivers their Present Plan ....... and it is always infinitely more exciting and rewarding when human to be engaged and inquisitive, isn't it.

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Re: To Stop Futures and Derivative Plays as Presently Planned for the Past ..... Believe in Miracles

LINE!

Oh. Sorry.

I thought this was buzzword bingo.

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Re: To Stop Futures and Derivative Plays as Presently Planned for the Past ..... Believe in Miracles

"I thought this was buzzword bingo."

No. Just AMFM

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Anonymous Coward

Re: To Stop Futures and Derivative Plays as Presently Planned for the Past ..... Believe in Miracles

I thought it was word spaghetti.

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This post has been deleted by its author

Anonymous Coward

Re: To Stop Futures and Derivative Plays as Presently Planned for the Past ..... Believe in Miracles

Come on, mars.

"a design principle where speculative state is stored in temporary structures that are not accessible by committed instructions,"

Doesn't that sound like a poor classical man's implementation of Nature's Quantum Mechanics. It's all there, but to progress, you have to choose one.

I'm awaiting Intel "Xeon Semi-Deadcat" in 5 years, where no credit will be given to the discussed paper.

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Holmes

Re: To Stop Futures and Derivative Plays as Presently Planned for the Past ..... Believe in Miracles

"Daily Zeroday News" sounds intriguing, and it actually exists!

https://www.hackerone.com/zerodaily

That's more than enough to terrorize any Status Quo.

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Anonymous Coward

Re: You have to choose one (-:

Ah. How possibly wise and secure to think planymetricall, while you have to think in 3d - being a quantum communication chain yourself.

Universe expects, etc. Is it a modern restore of a human - to have brain and, in the same time, have none?

Have a nice day in this box. Whatever happen inside of it, most of the observers will have hope for good.

Because there is a cat inside. Do you feel sympathy to it? Add to its chances, cross your fingers for it.

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Anonymous Coward

Hardware having to make up for cr*ap programming

I think that the main problems we have is that we now have to rely on hardware to speed up our cr*p programming skills.

In the days before limitless memory, storage, CPU power and when CPU pipelining started to appear in processors (1990s) the optimisation was built into the compilers and their methods/quirks/style guides were published so that programmers (NOT CODERS) were able to use them intelligently.

Now every CODER thinks they are a programming genius and knows how to write efficient code and the bean counters are happy because the coders can knock out code quickly and cheaply.

Relying on hardware sort out some poor excuse for a piece of programming is always going to have unintended consequences and leave a snake's nest of possibilities for side attackes.

</Rant>

Now back to watching the Le Mans cars bouncing off each other/the barriers during the night.

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Re: Hardware having to make up for cr*ap programming

You do realise these problems are hardware based problems with chip design and nothing whatsoever to do with programming?

The fact you get infected by programs is a side effect of how we use computers, but the issues are hardware based speculative execution flaws.

As for the mess of programs, that is because programming has been made more accessible. The more accesible a skill is, the more the quality is averaged out. To be fair though, the coding generally isn't all that bad, it's just the amount of things that are trying to run at once and are competing for limited resouces that becomes the problem.

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Anonymous Coward

Re: Hardware having to make up for cr*ap programming

- Why is Anonymous Coward getting downvoted?

- The OP does have a point, but keep in mind that the effects of removing speculative execution is not exclusively caused by bad programming.

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Anonymous Coward

"Abu-Ghazaleh acknowledged that SafeSpec requires some extra space on the L1 cache, but he considers the hardware changes to be minimal. And in terms of performance, he said, SafeSpec could even offer small improvements."

As somebody who works in this field, these conclusions seem unlikely to be true.

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Anonymous Coward

Ah.

So it is a hardware fix. I misread the rest of the article to be a software/firmware solution. :(

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Re: Ah. And a Response to Something Relatively New for Doing Private and Pirate Deals With

This might be initially misunderstandable but please do persevere to realise more of the programming to be true and made readily available to you for Current Presentation..... Future Revelation.

So it is a hardware fix. I misread the rest of the article to be a software/firmware solution. :( .... Anonymous Coward

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AILeading Space for Immaculate Source Providers, a la Turing Type Leads to Quantum Communications Machines. Advanced IntelAIgent Media Machines Revealing urFutures .... with what worlds have in store for All to Enjoy Best with Almighty Creative Use ..... and with Passion Servering Desire and Delivering Unquenchable Satisfaction for Perfect AI Applications, is an Titanic Epic AIDVenture.

And where that takes you, with what Quantum Communications Machinery Does So Easily Provide in AI Pioneer Positions, and what can be done in the Space before you to Exercise and Crash Beta Test with and for AIMaster Quantum Communications Piloting Controls Delivering Future Pleasures.

One can only begin to imagine what Almighty Use Perfectly True Hedonists would be Able to Enable, Exercise and Enjoy There Then, and Now Here Too in Spaces unveiling Places on Virtual Pages for Universal Presentation ..... and Globalised Virtual AIRealisation ..... is, well, and let's not beat about the bushes here, Almighty Immaculate Virgin Territory for Hosting with Heavenly Asset Suppliers. ..... Immaculate Source Providers.

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What would that be classified and/or weaponised as .... Toxic/COSMIC/ExtraTerrestrial/Alienating?

And in a world with worlds dominated by markets at their work, rest and play, one just has to ask ..... Just take a Wild Guess at how much all that is worth? Are there any numbers to truly express and represent the value?

Is Sir Richard Branson into The Virtual Enterprise with AI Concepts Realisation Programs/Advanced IntelAIgent ProgramMING Personnel?

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Mushroom

Re: Ah. And a Response to Something Relatively New for Doing Private and Pirate Deals With

I think I may have a problem. A serious problem.

I've just read the entire of two of amanfromMars's posts in the space of a few minutes and my brain is now going to suffer for the rest of the day. Luckily it's a Monday and nobody is likely to notice because I have long perfected the blank look when somebody foolishly asks me about that something that happened the other side of the weekend...

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As somebody who works in this field, these conclusions seem unlikely to be true.

The performance claim is based on running a suite of benchmarks against an emulator. Hard to say what would happen with real silicon, but it's not a complete SWAG.

The hardware overhead, on the other hand... the paper says 17% increase in area and 26% in power. That may well be acceptable for many applications, but it's a pretty big price to pay for others.

There is, after all, no free lunch. Resources you take to create shadow structures can't be used for additional sets of primary structures. The paper describes some clever ways to optimize shadowing and reduce the overhead (a naive implementation would make much less efficient use of cache lines), but as you suggest, there's going to be a cost.

And since this approach requires significant CPU redesign, it's not likely to produce a chip that lets the OS flip a switch - SafeSpec or use-all-resources-for-primary. So CPU manufacturers would have to decide whether they want to cater to security-focused or performance-focused customers. Or manufacture two design families.

And, of course, we still have other side channels ("other structures would have to be hardened too").

Don't break out the party hats yet.

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Anonymous Coward

Re: Ah. And a Response to Something Relatively New for Doing Private and Pirate Deals With

Rick. Knock-knock is not a kick-kick. Boom a Tom.

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Boffin

I have a simple plan...

1. Remove all speculative and predictive nonsense.

2. Treble the clock speeds.

3. Make much faster memory.

My fix is called 'SPECless' and the logo will be a stock photo of a young smiling woman in a low-cut top, staring happily at her mobile, and not wearing glasses!

This one looks about right - I realise she's showing more teeth than the average horse, but she does look very happy: https://www.istockphoto.com/gb/photo/happy-message-gm694767632-128422759

Who's with me?

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Re: I have a simple plan...

Are you sure you understand the complications of removal of speculative execution? Increasing clock speeds doesn't solve the problem, nor does making "faster memory".

Disabling "speculative and predictive nonsense" could easily set the world back to 2005 (or even before that) in terms of computing power.

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Re: I have a simple plan...

"2. Treble the clock speeds."

Intel called. They want their P4 NetBurst CPUs back. If you'll look back, you soon realize you can't just run everything faster. It just doesn't scale. Why do you think CPUs weren't and even today aren't specced much higher than 4GHz in clock speeds? One word: HEAT! The problems Intel had with NetBurst were the reason they had to take a step back to the P3, work smarter instead, and the end result is their current CPU line, the Core series.

"3. Make much faster memory."

There isn't much you can do about faster memory anymore without side effects. The biggest obstacles at this point are the speed of electricity combined with cycle lengths. In one nanosecond, electricity can travel, at most, about a foot. And yet you need at least some spacing due to all the heat both the CPU and the RAM inevitably kick up.

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Re: I have a simple plan...

"3. Make much faster memory" to be honest, we already have much faster memory, it is called SRAM - sadly required power makes it not practical for anything beyond small amount inside the CPU for caches. I agree that we should invest in research (and productisation) of new types of memory, optimised for very low latency.

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Re: I have a simple plan...

With you on the pretty picture or the hardware wish list? :)

Others have already made comments on the hardware wish list. However something that would help with performance mitigation is processor architectures that have considerably more executable cores, likely with different requirements and capabilities depending on task/process requirements. This would require potentially substantial changes to operating systems and many applications would have to be updated to "request" the appropriate processing requirements but it would allow a good deal of optimisation of use. For example, an audio decoding process would not need a huge amount of CPU power but does require very regular servicing (there is some support for this kind of thing already, but more would be better).

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Re: I have a simple plan...

Actually in a nanosecond the electrons will have for all intents and purposes no moved. Electrons move Very slowly in circuits, the effects move very fast.

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Re: I have a simple plan...

Are you sure you understand the complications of removal of speculative execution?

It depends, really...

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