a "Q" about forcepae -- and helpful answers

[cobaka]

Hello all:

The forcepae command is used with the Pentium "M" series CPU to force compatibility (or bootability) with the Puppy OS.

Dell Inspiron D800 and 8600 laptops use the Pentium "M" CPU.
I used forcepae previously with a Dell 8600 laptop - allowed me to boot an otherwise un-bootable laptop.
In that case I added "-- forcepae" to one line in the boot-loader. Note the double dashes before the command.

Now, I am configuring a Dell D800 - and I found the same block to booting. BUT! Being a Puppian of long memory .....
this was easily solved - this time using the command "forcepae". Notice that the two dashes are missing.

What's going on here? Why the difference between the two laptops and what (oh what) does forcepae do?
BTW - thanks to BigPup for getting the 8600 to boot (some years ago now).
Anyone here got SoDIMM DDR2 1GiB modules they want to sell? I need another GiB in the memory slot.

Woof to all!

cobaka

[rcrsn51]

In the previous setup, did you know for sure that the -- was required? Or did you just use it because someone suggested it?

[cobaka]

@rcrsn51

In this link -> https://www.forum.puppylinux.com/viewto ... epae#p6674
you will find I had a long discussion about this topic with the well-known (and almost famous) BigPup.
BigPup is a well informed and very helpful fellow.

The answer to my Q isn't important.
I'm just trying to understand what's going on.

Cobaka.

[bigpup]

This is all about supporting more than 4GB of memory in a 32bit OS. 32bit OS is limited to support max 4GB of memory.

So a way was figured out how to get it to support up to max 64GB.

PAE (Physical Address Extension)

In computing, Physical Address Extension, sometimes referred to as Page Address Extension, is a memory management feature for the x86 architecture.
PAE was first introduced by Intel in the Pentium Pro, and later by AMD in the Athlon processor.

The Linux kernel includes full PAE-mode support starting with version 2.3.23, [24] in 1999 enabling access of up to 64 GB of memory on 32-bit machines.
A PAE-enabled Linux kernel requires that the CPU also support PAE. The Linux kernel supports PAE as a build option.

Linux distributions that require PAE may refuse to boot on Pentium M family processors because they do not show the PAE support flag in their CPUID information (even though it is supported internally). However, this can be easily bypassed with the forcepae option.

All kernels for 32bit Puppy versions, seem to now only be configured to use PAE. They do not provide a pae or non-pae kernel.
So they are configured for using pae and expect to have it available in the computers CPU abilities.

As I understand it.
If the CPU cannot provide pae support. The CPU never was built to have it.
Nothing will make a 32bit Puppy, with a pae configured kernel, boot on this CPU.
In the past Puppy versions did get released as pae or non-pae versions.
Example:
slacko-5.6-4G-NON-PAE.iso
slacko-5.6-PAE.iso

[bigpup]

Using -- or not using it in the forecepae command is most likely something to do with this:
https://help.ubuntu.com/community/BootO ... ore--after

Older Puppy versions that did not have this kernel patch.

Kernel patch that changed the previous behaviour was:

commit 51e158c
Author: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon Apr 28 11:34:33 2014 +0930
param: hand arguments after -- straight to init

The kernel parses parameters from the kernel command line up to "--";
if it doesn't recognize a parameter and it doesn't contain a '.', the
parameter gets passed to init: parameters with '=' go into init's
environment, others are passed as command line arguments to init.
Everything after "--" is passed as an argument to init.