Vista 32bit with SP1 detecting all 4gb ram!?

[IceDigger]

Just installed sp1 for my 32bit vista home prem and it is now detecting all 4gb of ram. Is my computer possesed or what?

[pallesen]

yes, in their wisdom microsoft decided to change that. But they still don't support it, they just display it

[OldMX]

Nah, its just a cosmetic fix, windows still uses 3.5 gb tops of ram

[IceDigger]

darn

[pallesen]

the day hell freeze over they might change their mind and give us access to >4GB, without going 64bit

[Mithent]

It's nothing to do with changing their minds, 32-bit address space doesn't allow it. (And going PAE is not the solution, it introduces incompatibilities of its own and you may as well go 64-bit if you're doing that. It's not even true 32-bit.)

[pallesen]

Yes, they say pae equals trouble because of bad drivers. But maybe not all people are affected by such drivers. If you only have good drivers, it works like a charm

Anyways, I said "when hell freeze over" :)

[ryan_975]

Yes, they say pae equals trouble because of bad drivers. But maybe not all people are affected by such drivers.

Anyways, I said "when hell freeze over" :)

What is so hard about "going to 64-bit"? PAE was a hack and ill-supported by third parties. 64-bit is an official implementation and support is tightly regulated (at least with Vista, XP x64 not so much). I'd rather use the much better implemented and more flexible option than a hardware hack.

[pallesen]

PAE is not a hack. What gives you that idea?

I don't mind going 64bit.I just had a funny moment

[DeaconFrost]

What is so hard about "going to 64-bit"? PAE was a hack and ill-supported by third parties.
Because pallesen would miss out on all the fun and joy of posting the same lines about PAE in each and every thread this is discussed in. For everyone else, if you want 4 GB, legitimately, without any hacks, shortcuts, black magic, implementation, configuration setting, or whatever else you want to call it, x64 is definitely the way to go.

[pallesen]

It is very legit to wonder about it. The internet is full of references to it. And since both xp and vista comes with a pae kernel many people wonder why they still cannot pass the 4G

[DeaconFrost]

I'm sure there are numerous references to it, and some valid situations to use it. I was just taking a good natured zinger.

[pallesen]

And if it wasn't for the bad drivers, it would be the perfect solution to have all 4 GB RAM addressable. Heck, Microsoft had support for it in xp pre-sp2

[sumofatguy]

'displaying it' and 'using it' are two different things...

http://technet2.microsoft.com/WindowsVista/en/library/005f921e-f706-401e-abb5-eec42ea0a03e1033.mspx?mfr=true

[Mithent]

Using PAE is basically going to a 36-bit OS which only shows a 32-bit virtual address space to non-PAE-aware programs (nearly all of them). Even the PAE-aware applications have to use a windowing technique and can't address all their memory at once. It was sometimes useful for high-end servers etc. to use PAE to make use of more RAM - before 64-bit CPUs were available.

Now that we have native 64-bit CPUs there's no need to use this stop-gap method any more; if you're going to write drivers that support 36-bit address space, why not just go all the way and use 64-bit address space, avoiding all these windowing issues and giving plenty of headroom for the future? It makes more sense to just move to the new standard architecture and be set for the next few decades than to endure similar potential compatibility issues to move to a hybrid 36-bit system with addressing limitations which will be outdated much more quickly.

After all, ten years ago I think it would be fair to say that 128MB/256MB of RAM would have been common, and now it's not unusual to see 4GB RAM, a 32/16 times increase. If a similar increase was seen over the next ten years, we'd be at 128GB/64GB and be hitting or exceeding the limits of what you can address with PAE. The 64-bit limit is unlikely to be met any time soon, though.

[pallesen]

We're not talking 100xgigs of RAM here. Right now we're just talking about 4 GB. And the fact is, with PAE you can use it all, if Microsoft didn't choose to cripple the pae kernel. And yes, each application has a default user space of 2 GB, you just have to live with that. But often you run several apps at a time, so you can make full use of it

[masteraleph]

We're not talking 100xgigs of RAM here. Right now we're just talking about 4 GB. And the fact is, with PAE you can use it all, if Microsoft didn't choose to cripple the pae kernel. And yes, each application has a default user space of 2 GB, you just have to live with that. But often you run several apps at a time, so you can make full use of it

MS crippled it because of bad drivers and crashes. It shouldn't be too much of an issue anymore, but I know that the original Geforces had that issue, and for a time nvidia drivers had an issue in general (somewhere around the 8x.yy generation). They may be fixed now, but it's enough of a problem to keep PAE crippled, especially when everything works with x64.

[Sycraft]

There is no "deciding" to give you access to all 4GB of memory. It isn't a Windows thing that you can't get at it, it is a system architecture thing. Unless you can change how the system works on a hardware level, this is just how it is going to be.

I'll let Dan (http://www.dansdata.com/askdan00015.htm) explain it, since he is quite good at such things. Bottom line is this is just how systems are going to work. If you want access to more memory, quitcherbitchin and get a 64-bit OS.

[pallesen]

There is no "deciding" to give you access to all 4GB of memory. It isn't a Windows thing that you can't get at it, it is a system architecture thing. Unless you can change how the system works on a hardware level, this is just how it is going to be.

If we take for granted that there is hardware support for more than 4 GB, and there is memory remapping - the kind of support that is needed to be able to see it all in your 64-bit OS, then you can do the exact same thing with pae in 32-bit

[Eva_Unit_0]

PAE is not just a magic switch that magically frees up your "hidden" ram in a 32-bit operating system. As stated many many times, it was merely a cheap hack to allow 32-bit servers to have more than 4gb of ram, since around the time 64-bit cpus first started showing up 4gb was easily attainable in a large corporate server. It wasn't pretty, but it was the ONLY POSSIBLE WAY for servers on the cusp of the x86_64 transition to have enough memory.

However, it has a lot of problems with it. First and foremost, it drastically slows down the kernel when doing paging operations. If you have PAE enabled, then all memory accesses are slowed down considerably (because of all the extra page table shit it has to do). It breaks most drivers. Please, people, stop looking for PAE to come riding to the rescue and fix your memory issues. All it does is trade one problem for like 10 more.

[pallesen]

For the last time, it is not just a "cheap hack". Just because some vendors write bad drivers, doesn't mean PAE is bad.

Talking about page tables. In PAE the page table has 3 layers. In 64-bit it has 4 layers. So which one is more complex to handle?

[Sycraft]

If we take for granted that there is hardware support for more than 4 GB, and there is memory remapping - the kind of support that is needed to be able to see it all in your 64-bit OS, then you can do the exact same thing with pae in 32-bit

No, not so much actually. PAE is like EMS/XMS of days of old. So the way it works is you define a window of RAM in the 32-bit address range that will be used for high memory access. How big you set the window defines how much you can access at once. You then slide that around the high RAM area to access the data you want.

This is, as anyone who programmed back in the DOS days will tell you, a really nasty hack. Windows supports it via something called AWE, but it isn't the sort of thing useful to the system overall. Rather an app that is aware of it and has use for it like SQL server will then handle all the stuff.

So the answer is just to STFU and get a 64-bit OS. There is no reason not to if you need more RAM. It is simply a much better solution. Even if it would work, there'd be no reason for MS to try and use PAE in this fashion since 64-bit processors are now cheap and readily available.

[pallesen]

No, go research what PAE is all about.

AWE is not PAE

[sparks]

pae is included in xp sp2...
and 32 ain't going to get to 4 gigs no matter how hard you try.

2^32 = 4 294 967 296
4 gigs...well 1024 per meg x 1024 for gig = 4096
ok it looks like it but it aint LOL
subtract all the overhead reserved for winders in lower memory and it just doesn't get there

[pallesen]

Yes, sp2 - and vista - has a pae kernel, but it is crippled, obviously, otherwise you would have full access. It is there to provide dep support.

Due to the way memory access is handled, that math doesn't tell you anything about how much physical memory you can address. It is all up to the MMU and how many bits you use in the page table to describe the physical address