Red hat issued a vulnerability alert and include Z and Power: 
https://access.redhat.com/security/vulnerabilities/speculativeexecution

It provides no details of why. Given the different pipeline architectures I'd 
like to know why.

The fix for Intel et alii appears to be separate address spaces but Z has 
always had that.


-------- Original message --------
From: John McKown <[email protected]>
Date: 1/4/18 09:14 (GMT-05:00)
To: [email protected]
Subject: Re: [LINUX-390] Meltdown/Spectre; Linux on z affected?

On Thu, Jan 4, 2018 at 7:36 AM, Guest, Darren <[email protected]>
wrote:

> Hi,
>
> Not sure if people have seen that attached article or heard of the 'intel'
> chip issues from elsewhere:
> https://www.theregister.co.uk/2018/01/02/intel_cpu_design_flaw/
>
> The 'fix' for meltdown (at least) is apparently to change the Linux kernel
> which will potentially affect performance. I'm pretty sure that zSeries
> isn't affected by the issue (is it?), but if the Linux Kernel is changed,
> are we likely to see a performance hit on Linux running on zSeries as well
> (even though we don't need the fix)?
>
> Best case scenario, can I tell my management that these won't affect Linux
> on z?
>

​I am not any kind of Linux internals wizzard. But this exploit takes
advantage of a _HARDWARD_ flaw in the Intel CPU. Linux on z does not run on
an _Intel_ chip. The story, that I've read at least, specifically mentions
that​ most AMD chips are not affected; nor are ARM chips. So why would the
z chip? Of course, management usually being composed of hardware illiterate
"liberal arts" majors, perhaps it would be a good idea for IBM to
explicitly announce to the work that this flaw does not affect the IBMZ
machines.



>
>
> Cheers,
>
> Darren
>
> Darren Guest
>
> First Aider
> Senior Fire Executive
> Senior Systems Engineer
> Mainframe OS
> Global Technology Services, Experian UK
>

--
I have a theory that it's impossible to prove anything, but I can't prove
it.

Maranatha! <><
John McKown

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