Re: [Freedos-devel] Wait don't fix you code bug!

2017-06-30 Thread Rugxulo
Hi,

On Fri, Jun 30, 2017 at 8:02 PM, Jerome Shidel  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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[Freedos-devel] Wait don't fix you code bug!

2017-06-30 Thread 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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