torios team mailing list archive

[Nio Wiklund <nio.wiklund@xxxxxxxxx>]

Den 2014-08-22 16:54, Israel skrev:
> Hi Nio!
> 
> On 08/22/2014 09:28 AM, Nio Wiklund wrote:
>> Den 2014-08-22 15:33, Israel skrev:
>>> Hi,
>>> Has anyone had any success finding any info out about the PAE issue?
>>>
>>> a. can we install a non-pae on a pae device and it work using OBI?
>>> b. is it easy to get a pae kernel in Trusty?
>>>
>> Hi Israel,
>>
>> a. Yes, we can install a system with a non-pae kernel in a computer with
>> a PAE CPU. (I have done it many times.)
>>
>> Or do you mean the opposite? To install a system with a pae kernel in a
>> computer with a non-pae PAE CPU. Pentium M and Celeron M have PAE
>> capability but no PAE flag. They work with fake-pae and forcepae. Old
>> CPUs without PAE capability are actually hard to find nowadays, and are
>> usually too weak for a modern linux system anyway. Maybe DSL may work or
>> a simple text base debian system. Anyway non-pae CPUs need non-pae
>> operating systems.
> I have been staring at CmakeLists trying to force Precise to FindFLTK so
> my brain is a bit jelly right now :)
> 
> I think the main issue is the PAE flag. I did mean the opposite. 
> Installing on non-pae for the older laptops that don't set the flag in
> the processor.  Like 12.04 Lubuntu offering a non-pae installation option.
> 
> Can this be done in OBI by using a pae kernel on a non pae?
> as in, the very last section (C) on this page...
> https://help.ubuntu.com/community/PAE

Yes, this was the fundament for my work with Lubuntu-fake-pae

https://help.ubuntu.com/community/Lubuntu-fake-PAE

The best alternative for 12.04 LTS is to deliver it with fake-PAE.
Otherwise Pentium M and Celeron M will boot from grub, but not
'dist-upgrade' to new pae kernels. It is also possible to deliver it
with an old non-pae kernel. Lubuntu and Xubuntu 12.04 came with non-pae
kernels originally.

> So does the whole non-pae issue arise from a flag that a processor
> doesn't set, even if it is PAE.

Yes, almost. (There are also some rare CPUs with similar 'horsepower' as
old Pentium M CPUs that are claimed to lack PAE capability, Transmeta
Crusoe and some old Via processors.)

> I am trying to understand whether or not we can install trusty on a
> non-pae flag computer with a normal (in the repos) kernel, or whether we
> need to use Precise to do precisely this :)

Yes, if PAE capable but without PAE flag, you can use the boot option
forcepae in Trusty. See

https://wiki.ubuntu.com/Lubuntu/AdvancedMethods#Pentium_M_and_Celeron_M

> OR, is it possible to use phillw's kernel and have it stay up-to-date in
> trusty?  Or is it needed only for the Live image?

It is possible to have Phill's non-pae kernel. I think he intended to
keep it up to date, but you have to ask him directly how and for how
long he manages to do that.

The PAE live image can also boot with the boot option forcepae in
Trusty, but not in Precise.

> I hope I am more clear, but it is hard to mush my thoughts back together
> :)  And I don't entirely understand the pae issue.

Ask again, I'm glad to help you. I think I understand the PAE issue, but
may not explain it well enough.

(I think that the main problem is that the Ubuntu development team
forgot about Pentium M and Celeron M, when they decided to skip the
non-pae kernel. And when the decision was there nobody wanted to reverse
it. I also think forcepae is a good work-around, and I would be happy,
if it could be back-ported from Trusty to Precise, because some drivers
for old hardware were dropped between Precise and Trusty.)

>> I can also run Phill's non-pae kernel in my Toshiba with Intel i5 (which
>> has 64-bit architecture). I have made installations with two kernels,
>> the default 'generic pae' and the non-pae kernel. Both work, but the
>> non-pae kernel cannot use RAM above 2 GB as efficiently as PAE (of
>> course). But UEFI demands 64-bit systems.
>>
>> b. Yes, you get it by default in Ubuntu based systems. If you have only
>> a non-pae kernel you can install the current PAE kernel with
>>
>> sudo apt-get install linux-generic-pae
>> probably even
>>
>> sudo apt-get install linux-generic
>>
>> will install it. Try it yourself :-)
>>
>> If I remember correctly, it is one of the menu alternatives in
>>
>> http://phillw.net/isos/linux-tools/9w/obi_Trusty-nonpae-txt5-9w.iso
>>
>> Best regards
>> Nio
>>
>>
>>
>>
> 
>