Simple XP 32BIT 64Gb RAM (true Pae) Guide

[reboot12]

Which patch for WinXP SP2 ? I tried WinXPPAE_v35.7z but patch only ntkrnl*.exe

Search for differences

1. C:\WINDOWS\system32\ntkrnlpa.exe: 2 015 232 bytes
2. C:\WINDOWS\system32\ntkrnl2.exe: 2 015 232 bytes
Offsets: hexadec.

   138:	D9	23
   139:	22	1E
15BF1B:	07	00
15BF20:	01	02
160F0E:	74	EB
1B07CC:	10	00
1B07CD:	00	02
1B07E2:	1B	00
1B07EA:	FC	F8
1B07EE:	01	02

10 difference(s) found. 

I try use patched files from Dibya128GB -> ntkrnlpa.exe + hal.dll but OS not boot and only black screen.

[user57]

On 1/2/2017 at 4:19 PM, liquidLD said:

yes, on 32 bit XP . It's my understanding that in a 32 bit PAE system,no app can acces more than 3-4 Gb, but the system can utilise in some manner all the memory available.

So,even if one app cannot use,let's say ,more than 3 or 4 Gb, the OS,as a whole can. And it's always good to have lots of memory. Especially when you run many apps at once.

edited for some grammar mistakes (not a native speaker)

there are 3 that can exceed the 4 GB limit

PAE

PSE

PAGING

lets say this patch works, it dont exceed the normal 4 GB limit what rather is like 2 GB per running executable/app - this is because the usermode useally takes 0-7FFFFFFF addresses 

the rest is in kernel mode (80000000-FFFFFFFF)

so somewhat somehow it can use that 4 GB per app, but its split apart (2 gb usermode memory and 2 gb kernel mode memory)

 

to have a little more userspace, there is a smaller solution to pass that 2 GB limit to a 3 GB limit

https://learn.microsoft.com/en-us/windows/win32/memory/4-gigabyte-tuning

then the usermode limit is 0-BFFFFFFF and kernel mode is C0000000-FFFFFFFF

(3 gb usermode, 1 gb kernelmode)

but back to that important answer, normal apps dont use for example segments to exceed that 2 GB/maybe 4 GB limit 

 

but there is actually a different reasoning why the 64 GB are use anyways 

and that reason is that you dont have just 1 app/executable running on XP

those different apps then can point to a different spot in memory (aka passing the 4 GB limit)

so having multiple applications (for example google use a lot of extra/or restarting applications/executables) is also a solution to use the 64 GB ram

 

have the patch ever tryed to be functional ? norm-wise it is certainly possible, someone might actually run a lot of big applications and check what physical memory pages are mapped out

 

to make a paging example there are segments

https://en.wikipedia.org/wiki/X86_memory_segmentation

but XP barly use these segments (nor do 7 8 or 10 - and if they do they are not used to pass the 4 GB limit)

for example in a older normwise app there is this segment (often called a selector) that is using the CS:EIP combination to execude the code flow, while the data access DS selector can access a different part in memory - but that wasnt happening - both DS and CS where made to point to the same memory in like win98-win10 OS`s

the ES segment for example could be a choice to pass the 4 GB limit over the segment solution

a even simplier idea would just to use the next counter for CS 

 

but if you then disassembly the applications you can see that the executables/apps are not using that - that goes for 99 %+ of apps/executables - also they cant if the OS/kernel mode dont have a controlment for this

the most applications/executables dont have the selector being used

but you can write an access with like a code using "cs:offset" instead of just "offset"

 

besides the software, also a role plays if the hardware can do it, some still have 32 wires, then the CPU might be able to do so, but the motherboard dont have enough wires

[j7n]

If you have a lot of RAM memory (to make use of PAE) that in itself consumes space in the kernel memory where a translation table is kept. Drivers allocate kernel memory for their own needs. For this reason /3GB might lead to instability with only 1 GB left over. /USERVA allows to tune the boundary to give a little more user memory, such as 2.5 GB.

[user57]

maybe it would be possible over this what microsoft calls AWE

https://learn.microsoft.com/en-us/windows/win32/memory/address-windowing-extensions

however it seems to give control over physical pages but it is connected to a virtual address

but it is not using a selector 

 

going with only 1 executable, that means you might can map more then 4 GB of data piece wise

but always when you want to access that RAM/data you have to remap it to a virtual offset

 

and just thinking around if that AWE is used by internal functions of windows - thats maybe how windows xp passes the 4 GB limit - in a post before i wrote its possible to map the other ram (higher then 4 gb) in a 32 bit system (or with a different name "pages") 

thus xp could map ram above 4 GB in multiple applications (that sounds very similiar to what i wanted to point out)

 

having the "multiple app/executable" solution is not that bad so you actually use up the 8 GB 16 GB or whatever you have installed in your computer

chrome is the best example right now i have 24 open executables of chrome (with 3 times google started up)

[reboot12]

OK, finally works 

I was running all the time with CSMWrap and it turned out that with this it doesn't work on Haswell:
https://forums.mydigitallife.net/threads/winxppae-v3-5-winxp-sp2-issue.89363/#post-1881947

Also, the ntkl64g.exe file has a bad checksum and doesn't work when trying to run using winload.exe - error 221:

setcsum ntkl64g.exe

 SetCSUM v1.01, (c)2000 Jeremy Collake
 http://www.collakesoftware.com
 mailto:collake@charter.net
 ----------------------------------------------------------------------
 .\ntkl64g.exe =
    Header Checksum:  001FACDE
    Correct Checksum: 001FF99B
    Checksums do not match!
     Set correct checksum in file? [Y/N/Q] Y
     Recompute
     Header Checksum: 001FF99B
     Correct Checksum: 001FF99B
     Checksum set!

 Done!