[X86] x86 SIG / Dropping PAE support

[Jeff Backus]

Hi List,
I wanted to reach out to you to let you know that we have established an
x86 SIG in an effort to help address x86-related issues in Fedora. To help
https://bugzilla.redhat.com/show_bug.cgi?id=1489998
https://bugzilla.redhat.com/show_bug.cgi?id=179258
Please feel free to also reach out to us via the x86 mailing
Also, I wanted to let you know that we have decided to drop PAE support. I
believe the kernel team has already disabled it for F27. They pointed out
that this may affect Anaconda as well. And that the Lorax templates may need
to be updated?

We are not dropping PAE for F27, it is a bit late for that. We have disabled
for rawhide/F28

Doh! Right, sorry. F28. Makes more sense. Sorry! :)

jeff

[Jeff Backus]

Also, I wanted to let you know that we have decided to drop PAE support.

Does this disable direct NX support, too?
Thanks,
Florian

Hmm.... Good question. Looks like it. I'm not very familiar with the
no-execute stuff, but yes, I do believe it requires PAE.

jeff

[Jeff Backus]

Post by Jeff Backus

Also, I wanted to let you know that we have decided to drop PAE support.

Does this disable direct NX support, too?
Thanks,
Florian

Hmm.... Good question. Looks like it. I'm not very familiar with the
no-execute stuff, but yes, I do believe it requires PAE.

Isn't this a rather significant feature regression?

Only from a security standpoint? *sheepish grin* Thanks for point this
out. We'll need to revisit.

jeff

[Stephen John Smoogen]

Post by Jeff Backus

Also, I wanted to let you know that we have decided to drop PAE support.

Does this disable direct NX support, too?
Thanks,
Florian

Hmm.... Good question. Looks like it. I'm not very familiar with the
no-execute stuff, but yes, I do believe it requires PAE.

Isn't this a rather significant feature regression?

Argh. This is an oversight on my part when bringing this as an option
from the kernel team. I was not aware that the NX was dependent on
PAE. The primary hardware that people were wanting all seemed to be
below 4 GB so having PAE didn't seem to be worth the overhead. I am
not sure if the OLPC desktops even have support for either NX or PAE.
The people with P-III or no SSE2 definitely don't have PAE.

[Florian Weimer]

Post by Stephen John Smoogen
Argh. This is an oversight on my part when bringing this as an option
from the kernel team. I was not aware that the NX was dependent on
PAE. The primary hardware that people were wanting all seemed to be
below 4 GB so having PAE didn't seem to be worth the overhead. I am
not sure if the OLPC desktops even have support for either NX or PAE.
The people with P-III or no SSE2 definitely don't have PAE.

PAE is *way* older than NX/XD, but as you said, it does not matter for
the old hardware because of RAM sizes and lack of NX/XD support.

There used to be an approximation to NX/XD based on segment register
limits, but the art of writing userspace applications to make use of
that may have been lost (and I don't know if the corresponding kernel
code bits still exist and are being maintained).

Thanks,
Florian

[Bruno Wolff III]

Is there a change page for this somewhere?

Note if you are using PAE kernels you just stop getting updates. Maybe there
should be some obsoletes to make the change over more transparent?

[Bruno Wolff III]

On Thu, Sep 21, 2017 at 06:01:48 -0500,

Yes, measures will have to be taken for that to happen, but given that it
isn't hitting most users until the F28 cycle, they have not been put into
place yet. In the meantime, manually installing a single non PAE kernel
will get everything back on track since you are following rawhide.

That's what I did. I was just confused for a bit when I saw kernels weren't
updating on my i686 machine. I eventually noticed there weren't PAE rpms
and went looking for a discussion about it to see if it was a short term or
long term change.

[Jeff Backus]

Hi List,
* One for General x86-related issues: https://bugzilla.redhat.com/show_bug.cgi?id=1489998
* One for x86 ExcludeArch-related issues: https://bugzilla.redhat.com/show_bug.cgi?id=179258
Also, I wanted to let you know that we have decided to drop PAE support. I believe the kernel team has already disabled it for F27. They pointed out that this may affect Anaconda as well. And that the Lorax templates may need to be updated?

Hi all,

Just following up on this.

Ananconda Team - how should we proceed. Should I file a bug to have PAE support dropped?

Thanks!
jeff