Re: [GIT PULL] perf changes for v3.8

From: Ingo Molnar
Date: Thu Dec 13 2012 - 02:30:51 EST



* David Ahern <dsahern@xxxxxxxxx> wrote:

> > But doing it this way was wrong. Switch that "exclude_guest"
> > attribute around, and admit that "H" was bogus, and that the
> > right thing to do was to add a "V" flag that sets the
> > "force_guest" flag instead.
>
> I understand this is annoying. [...]

It's not annoying, it's outright broken - it's a regression that
we'll fix.

> [...] Older binaries on newer kernels was the only case I
> could not fix. [...]

The "only" case?? Old, working binaries are actually our _most_
important usecase: it's 99.9% of our current installed base ...

> [...] (I guess a message could be added kernel side to at
> least give a hint.) But the alternative -- based on code that
> has existed for some time -- is for older binaries to crash
> VMs.

That should be fixed differently, by not breaking existing
working functionality.

Thanks,

Ingo
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