Mailinglist Archive: opensuse-factory (549 mails)

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Re: Fwd: Re: [opensuse-factory] Kernel clarification
  • From: Basil Chupin <blchupin@xxxxxxxxxxxx>
  • Date: Tue, 10 Nov 2009 15:53:07 +1100
  • Message-id: <4AF8F1B3.3070209@xxxxxxxxxxxx>
On 10/11/09 03:35, Jeff Mahoney wrote:
On 11/08/2009 01:57 AM, Basil Chupin wrote:

-------- Original Message --------
Subject: Re: [opensuse-factory] Kernel clarification
Date: Sun, 08 Nov 2009 17:37:08 +1100
From: Basil Chupin <blchupin@xxxxxxxxxxxx>
To: opensuse-factory@xxxxxxxxxxxx

On 08/11/09 06:54, Andreas Jaeger wrote:

On Saturday 07 November 2009 03:06:19 Basil Chupin wrote:

Forgot to mention: the CPU is AMD XP 3200+, 1.5GB RAM, 2x 500GB HDs,

The desktop kernel needs AFAIR PAE support, I'm not sure your CPU has it -
that might be the reason for the installation of the default one.

In general: kernel-desktop runs on "newer" hardware only, kernel-default
runs also on some older,


Thanks for this Andreas, but then the puzzlement deepens because in 11.1
the pae kernel was installed on my computer. See the attached menu.lst.

I don't have earlier versions of oS installed on HDs so cannot check but
I seem to recall the the pae kernel was also installed by at least one
other earlier version of oS.

I also remember "fiddling" with a copy of the kernel in 11.1 to compile
my own which had the (?some of the) qualities now in the desktop kernel
eg,the Timer Frequency set to 1000Hz.

Am I wrong or isn't it the situation that if the kernel is compiled with
parameters selected but which, in fact, are not available in the CPU
then the kernel still does its job and uses those which ARE available?
That is, it doesn't have a hernia, throw up its hands and runs off
screaming into the distance :-) .

No, that's exactly what happens. It examines the CPU feature set and
gives up if features aren't available.

In the case of PAE, it is because PAE requires 3 level page tables and
non-PAE requires 2 level page tables. They can't currently coexist.


Which is why the default kernel didn't collapse in a screaming heap
because my Athlon XP cpu does have pae support :-) , and the default
kernel in 11.2 does have pae support enabled as one of its parameters.

But surely suggesting what you did above that the kernel gives up if the
features are not available is a slight exaggeration? :-) If this was
the case then for every installation the kernel would need to be
compiled in real time to suit the cpu being used. Or is this where
modules come into play and are loaded if required? I am not an expert
and so am simply asking to be 'heducated' :-) .


I work to live not live to work.

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