Switching Fedora to pae kernel by default?

[Kyle McMartin]

On Tue, Jan 20, 2009 at 11:06:17AM +0200, Avi Kivity wrote:
> Eric Paris wrote:
>> I've got a P3 (Coppermine) with 256M memory running F10.  My significant
>> other took it with her to Antarctica (Well F9 has been to Antarctica but
>> it'll be F10 in Antarctica next month).  You can only run one app at a
>> time and have to be patient, but it's perfectly usable (and noone cares
>> if this laptop is lost, stolen or destroyed [aside from her being pissed
>> she lost all her research data]).  I wouldn't/couldn't to use it as a
>> daily machine, so while I'm in favor of -PAE default, F10 is "usable" on
>> such small machines.  I don't care if old machines need some bit
>> twiddling to get to work, but we aren't dead yet   :)
>>   
>
> By F12 you'll be down to zero apps at the same time, and slow...
>
> We can keep the non-PAE kernel, but as non-default in recognition that  
> technology has moved on.
>

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.

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.

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?

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...)

cheers, Kyle