windows 7 32-bit PAE hack

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venm11

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Is anyone familiar with this?

I've been using this for a few months as a workaround for my older 32-bit laptop to get at >4gb until I can transition. It's a hack for the 7600 kernel to enable PAE on a non-server windows OS. It does the job and I haven't had any problems.

The problem is that it only seems to be available for kernel build 7600. That means a downgrade from SP1 to [pre-SP1].

Does anyone know of such a hack for kernel 7601?

Does anyone know what changes were made to the kernel 7600 with 7601 ?
 
Once upon a time I did appcompat, and that is a concern, but DosBox seems to be pretty good at emulating dos apps, even though it was designed for games. But yes, Hyper-V or VirtualBox, or VMware could also be used.

But even so, I would never hot patch the kernel to put it into an unsupported state. I would also try to get to a 64 bit operating system as fast as possible, with all the security advantages.

This posting is provided "AS IS" with no warranties, and confers no rights.
 
AFAIK PAE support is disabled in Win32 due to the device drivers. The drivers can't handle extended address spaces which will lead into system instability (memory gets written over) if you try to enable PAE. And since Windows can have a gazillion different device drivers, trying to get them all fixed would be a gigantic endeavour.
 
B00nie said:
AFAIK PAE support is disabled in Win32 due to the device drivers.
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That is what they claim. However server versions of windows are not crippled in this way. So clearly at least some hardware vendors are capable of writing drivers that work correctly with PAE used to support memory over 4GB on a 32-bit system.
 
B00nie said:
AFAIK PAE support is disabled in Win32 due to the device drivers. The drivers can't handle extended address spaces which will lead into system instability (memory gets written over) if you try to enable PAE. And since Windows can have a gazillion different device drivers, trying to get them all fixed would be a gigantic endeavour.
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plugwash said:
That is what they claim. However server versions of windows are not crippled in this way. So clearly at least some hardware vendors are capable of writing drivers that work correctly with PAE used to support memory over 4GB on a 32-bit system.
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PAE isn't disabled. PAE will in fact turn itself on automatically on systems which support it, or can be explicitly enabled in the boot configuration.
http://msdn.microsoft.com/en-us/library/windows/desktop/aa366796(v=vs.85).aspx

The problem is that even with PAE most 32-bit copies of Windows, for licensing purposes, are limited to a 32 bit address space. This is because Microsoft would have to offer support for the larger address space on 32-bit, and this would be expensive because drivers do not cope well with the extended address space.
 
You wouldn't believe how many drivers were bugchecking when it was enabled and people had more than 4 gb of memory... I'm not sure it'd be a problem today, but today if you have more than enough memory, get rid of the PAE hack, and go with 64 bit windows.

This posting is provided "AS IS" with no warranties, and confers no rights.
 
Dogs said:
The problem is that even with PAE most 32-bit copies of Windows,
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Specificially desktop editions of 32-bit windows. Server editions don't have the restrictions on address space (though they do have restrictions on ram which are different between 32-bit and 64-bit versions)

Of course by number of copies sold the desktop editions presumably far outnumber the server ones.

for licensing purposes,
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They used the license enforcement mechanisms to enforce the restriction but that does not mean that the restrictions were "for licensing purposes". Afaict the license agreements for desktop versions of windows make no mention of amounts of memory.

are limited to a 32 bit address space.
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Indeed, my previous post wassn't strictly accurate. Strictly speaking they enabled PAE but then locked out the ability to actually use the extended physical addresses (PAE brings some other benefits too though which is why they enabled it)

This is because Microsoft would have to offer support for the larger address space on 32-bit, and this would be expensive because drivers do not cope well with the extended address space.
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I strongly suspect you are right here.

By limiting the feature to the server editions they both limit the number of people who will try to use it and get paid a lot more per copy where it is used. So the support burden is nowhere near as great as it would be if people with desktop editions were enabling support and wondering why it crashed.
 
plugwash said:
Afaict the license agreements for desktop versions of windows make no mention of amounts of memory.
Click to expand...

Before SP2, XP could make use of more than 4 GB address space with PAE, so you could get 4 GB usable system ram. But only up to 4 GB usable, so they don't want non-server editions to go beyond 4.
 
I'm reasonably sure you can still enable PAE via the boot config, bit MSFT forces addressing below the 4GB boundary because drivers tended to break.

In any case, I don't see a huge need; the Win32 memory addressing limitations are still in full effect, even with PAE enabled, namely, a SINGLE application is limited to 2GB Address Space usage. So for a single app, PAE isn't going to give any real benefit.
 
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