Mailinglist Archive: opensuse-factory (549 mails)

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Re: [opensuse-factory] Kernel clarification
  • From: Rob OpenSuSE <rob.opensuse.linux@xxxxxxxxxxxxxx>
  • Date: Tue, 10 Nov 2009 01:41:07 +0000
  • Message-id: <ce9d8ed60911091741k4e0738cbkfc3e87e69c5bb139@xxxxxxxxxxxxxx>
2009/11/9 Larry Stotler <larrystotler@xxxxxxxxx>:
On Sat, Nov 7, 2009 at 2:54 PM, Andreas Jaeger <aj@xxxxxxxxxx> wrote:

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

Kernel PAE was installed on 11.1 to enable the NX/XD bit on newer
machines, basically 64bit processors.  The only 32bit procs that
support it is the Atom, the Intel Core Solo/Duo & some of the Pentium
M procs(Banias and some slower Pentium M's don't have support for it).
 There was a lot of discussion about how the PAE kernel wasn't very
stable on some older hardware(I switched my P3 laptops to
default-kernel).

Personally, I'm not convinced that PAE should be enabled by default
because I'm not sure it's as efficient as not using it.  Very few
32bit systems actually have the ability to use more than 4GB RAM.

Yes, and PAE goes into meltdown according to Linus above the 8GiB mark.

The 64GiB old SuSE big smp kernels were effectively for "server"
boxen, when desktop was
synonymous with uni-processor. They used to waste fair amount of
kernel memory as
some kernel data structures were sized according to max number cpus.
On a 4GiB AMD64
box, installed with 32 bit 10.3, switching to default kernel was a
small performance win (and
more convenient with KMPs), though having NX/XD is nice security feature.

Those desktops with 64 bit CPU, and 2+ GiB RAM are best served by 64
bit OS. If they use the
RAM, the architectural advantages of AMD64 help, and if they don't
then avoiding a level of
indirection (and bounce buffers) is an advantage.

The 32 bit desktop, ought to be aimed at older & frugal hardware like
Atom, Geodes, Via,
with < 2 GiB RAM & small max CPU value, not for 64 bit "Forum
Refuseniks" who object to having
32 bit copies of system libraries on disk. Optimising for space, may
well make sense there to.

Rob
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