Switching Fedora to pae kernel by default?

Avi Kivity avi at redhat.com
Tue Jan 20 17:28:10 UTC 2009


Kyle McMartin wrote:
> Look, I'm sorry if I'm just not thinking big picture enough here, but
> what exactly is the use case for a PAE kernel these days? The compat
> code in x86_64 should be more than good enough for the apps that require
> an i686 chroot.
>   

It's certainly very good.  I converted my i386 install to an x86_64 one, 
and the intermediate step of running the i386 userspace on x86_64 kernel 
worked well.

> I just don't see the status quo as doing any real harm, as the only
> generations of CPU that benefit are really P4 (which aren't worth the
> electricity used to power them) or Core (One) Duo (which didn't exist
> for a particularly long time...) Neither of which actually supported
> more than 3GB of RAM on their northbridges except for the Xeon chipsets
> anyway.
>
> I have no idea what the installer and livecd do, but to me, it would
> seem to be a waste of space to carry two sets of installable kernels on
> the discs, when one would do. That said again, I'm suprised we aren't
> installing i586 kernels by default... Odd.
>
> I think the ideal solution here is to support x86_64 kernel, i686
> userspace more actively.
>   

I'm all in favor of pushing x86_64.  But I think currently most installs 
are i386.

> What, honestly, are the odds of someone with a bunch of P4 Xeons these
> days with 32GB of ram running Fedora? Are there really enough of them
> that it's worth caring? ;-)
>
> Of course, take what I say with a grain of salt. I don't particularly
> care at all, I'm just trying to play the pragmatist.
>
> Another question is what's the perf penalty of going to PAE on a
> 2GB of ram machine versus the vanilla HIGHMEM4G config?
>   

I'm guessing, pretty low.

> The only argument I really buy into is the NX one, honestly...
>
> What about a yum plugin that recommends a kernel that the user could
> override? I'll poke at it this afternoon (hey, I've always wanted to
> learn python...)
>   

Users won't be running yum.  They're running that applet thing.

-- 
error compiling committee.c: too many arguments to function




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