Wait don't fix you code bug!

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Wait don't fix you code bug!

Jerome Shidel
Hello all,

In case you haven't heard, there is a severe bug in Intel Skylake and Newer CPUs. I only know a little about it. From what I heard, it crops up with hyper-threading inside loops less than 64 bytes effecting several high byte registers (AH, BH, etc). They are working on a microcode patch and hopefully will have it out soon.

So, I guess it could effect DOS asm code running inside a VM.

I think it's been a while since there last major bug. Last one I recall was that Pentium 90 Floating Point problem.

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Re: Wait don't fix you code bug!

Rugxulo
Hi,

On Fri, Jun 30, 2017 at 8:02 PM, Jerome Shidel <[hidden email]> wrote:
>
> In case you haven't heard, there is a severe bug in Intel Skylake and Newer CPUs.

Most of us aren't trendy. This Nehalem Westmere (Core gen #1) is my
newest machine (so far).   ;-)

> I only know a little about it. From what I heard, it crops up with hyper-threading
> inside loops less than 64 bytes effecting several high byte registers (AH, BH, etc).
> They are working on a microcode patch and hopefully will have it out soon.

Don't panic! Bugs are part of life ("par for the course").

http://www.os2museum.com/wp/vme-fixed-on-amd-ryzen/

> So, I guess it could effect DOS asm code running inside a VM.
>
> I think it's been a while since there last major bug. Last one I recall was that Pentium 90 Floating Point problem.

You mean the FDIV bug? That was fixed in 120 Mhz (and higher) models.

But there have always been other cpu bugs:

* https://en.wikipedia.org/wiki/Pentium_F00F_bug
* (P3 serializing bug)
http://web.archive.org/web/20070808143526/http://clio.rice.edu:80/djgpp/r5bug05.txt

So this is far from the last one we'll see.

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Re: Wait don't fix you code bug!

Jerome Shidel


> On Jun 30, 2017, at 10:56 PM, Rugxulo <[hidden email]> wrote:
>
> Hi,
>
>> On Fri, Jun 30, 2017 at 8:02 PM, Jerome Shidel <[hidden email]> wrote:
>>
>> In case you haven't heard, there is a severe bug in Intel Skylake and Newer CPUs.
>
> Most of us aren't trendy. This Nehalem Westmere (Core gen #1) is my
> newest machine (so far).   ;-)

What? Are you telling me DOS users aren't trendy? ;-)

>
>> I only know a little about it. From what I heard, it crops up with hyper-threading
>> inside loops less than 64 bytes effecting several high byte registers (AH, BH, etc).
>> They are working on a microcode patch and hopefully will have it out soon.
>
> Don't panic! Bugs are part of life ("par for the course").

At least they claim they can fix it. :-)

>
> http://www.os2museum.com/wp/vme-fixed-on-amd-ryzen/
>
>> So, I guess it could effect DOS asm code running inside a VM.
>>
>> I think it's been a while since there last major bug. Last one I recall was that Pentium 90 Floating Point problem.
>
> You mean the FDIV bug? That was fixed in 120 Mhz (and higher) models.
>
> But there have always been other cpu bugs:
>
> * https://en.wikipedia.org/wiki/Pentium_F00F_bug
> * (P3 serializing bug)
> http://web.archive.org/web/20070808143526/http://clio.rice.edu:80/djgpp/r5bug05.txt

I was never bit by ether. So, my memory of them is foggy at best.

>
> So this is far from the last one we'll see.

No doubt. CPUs are complex little monsters.

>
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> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
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