OS: Windows XP Home SP2
CPU/Ram: Mobile AMD Duron 4, 1GHz / 256MB
System Manufacturer: Compaq Presario 730us

Using windiag.exe to test my RAM I get a consistent error for the following address: 0b5d9270. The system returns the wrong value, e.g. expects value f7f7f7f7 and instead gets f7f7e7f7. This RAM is on the motherboard and it's about as expensive to replace it than to buy a new computer.
Is there any small program that could be written so as to reserve/exclude this specific RAM address at boot so that it's not used? Unfortunately I know little programming ...
THANK YOU very much for your response, I really appreciate it.

Juan

Actually I meant to write "small assembler program"; somebody told me that one couldn't write it in C

With linux, you can (or could?) mark areas of memory as bad, and not have them used by the memory manager. With win9x, there might be a system.ini or registry settings, but I wouldn't know it. For NT, I believe there's a boot.ini switch to limit the amount of memory seen by the OS - but that would mean you can only use ~180 megs of those 256 megs. It might be possible to write a driver that allocates the specific areas of memory that are bad.

In case you haven't seen it, have a look at http://www.memtest86.com/ to pinpoint the exact areas that are bad.

f0dder, thank you very much for your reply. It's the closest I've got to a hint about how to proceed to fix it. Do you know anybody or any forum or any way to get this driver written? Do you think it's even possible? I've posted this questions to some C and C++ forums and everybody, without exception has told me it's not possible to do. However, it's seems to me logically possible so I'm surprised.
Juan
P.S. I have the exact address of the area that's bad (windiag.exe determined it)

I have a question and a sugestion, then where is the problem in the RAM or in the mother board????


The suesgtion is, I guess is posible to write a application pheraphs not necesary to be a driver, but instead of mark the address permanently, alloc some memory there making a "shield" around this address, dont know if is posible to use the mark of allocation directly for an address instead of let the OS select where is, if is posible that, then your programm will only run at startup, allocate a shield around this addres and by this flag of allocation, any other programm not will be able of request this memory.


Pheraphs you get the idea, andpheraphs is exactly equal dificult than do the driver, but instead of limit your memory to 160 you make make a shield of about some Kb, and you dont loss much memory .

Hope that sugestion serve, and the question that remain is: is posible to do a like allocation directly for a range of address, only for the porpuose of dont let others application use exactly this range of memory?

if its @ the end , win 9x has a function to set maximum memory to use, it clips the end

There's a thread in order to get started writing a driver of your own:
http://board.flatassembler.net/topic.php?t=256

Matrix, any idea of what function is that of win 9x that allows you to clip the end? It may work; I don't mind switching back to win98.

pelaillo, as far as you know, is there a function that could be used in a driver to either reserve or exclude memory with a certain phisical address?

Juan, if you're on NT, get hold of Four-F's KMD tutorials and perhaps also the NTDDK (for documentation). I'm pretty sure there's a way to allocate a specific memory region. Since your bad region isn't near the start or end of your memory region, I guess there's a good chance the memory isn't allocated by other drivers/applications if you load your driver at system boot.

It's been a while since I did driver development, and I never really touched memory allocation, so I don't know whether there's an "easy" API to use, or if you have to build MDLs describing the bad areas. But once you find the right APIs to use, it should be very easy to develop the driver.

It probably has to be done from a driver, though - I know of no ring3 APIs that allow you to reserve physical memory.

JuanPedro, as per f0dder's advice, the allocation cannot be done in ring3 because any allocation will be in virtual memory and is windows that decide the final physical address to use.

In win98 you may allocate the memory before booting windows (config.sys ?) or using a simple ring0 resident program that allocate the bad region. Once allocated, win98 detect it as used and skip it (by compatibility with old DOS programs)

run msconfig.exe
click to special, then set memory limiting
that's all

Where is Four-F? I was trying access http://masm32.cjb.net/ but I cant get the redirection and I dont know the real name ...

I posted a topic on hiro's board, have a look: http://www.win32asmcommunity.net/board/topic.php?p=153796

f0dder, pelaillo, what you say about winNT allowing me to allocate a specific memory region is also valid for XP?
I'll switch to NT if I have to; I currently have XP and I'm curious.
Thanks

f0dder, I just now realized about the topic you posted on hiro's board. It's great, thank you very much !!!!!
I don't understand most of it but you and these guys are terrific; I'll try to follow it and see what I can get from it.

Juan

I went into the topic posted into hiro's board and, even though I didn't understand much, I was able to realize that the suggested approaches led to something very similar to what Matrix suggested. In addition, as I was able to find out, Matrix approach is also do-able in XP (via boot.ini). This is very clean, easy and achieves the same thing as the suggestions in hiro's board.

f0dder, I wander if the approach suggested by the people who reponded to your posted topic may be used to actually selectively take out that memory address (0b5d9270) instead of just cutting off everything above 190MB as I had to do.

Some like this should be nice, http://msdn.microsoft.com/library/en-us/memory/base/creating_guard_pages.asp?frame=true

I have also watched that Windows CE have a function for alloc a address http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wcecoreos5/html/wce50lrfAllocPhysMem.asp

But is only for Windows CE, altought pheraphs something similar is posible for Windows.

Like write a driver that combine this two concepts using allocation and some flags like PAGE_GUARD|NOREAD|NOWRITE. Hehe, altought I think it should not be a easy problem?? to solve??

I had a quick poke around, and I guess some of these might be starting points if you feel like playing with driver development - unfortunately I don't have the time to play around myself right now :/

NTOSKRNL::IoAllocateMdl
NTOSKRNL::MmAllocatePagesForMdl
NTOSKRNL::MmProbeAndLockPages

Any progress?

I'm having the same trouble with a computer but with two defective address located at 6.0 MB and 6.5 MB. As you can see I can't just set a config to exclude all memory above 6.0 MB. Apart of MmAllocatePagesForMdl I found IoReportResourceForDetection and IoReportDetectedDevice that seems to be another way. The computer has a WinMe installed (and the user does not want another OS), can I use those function over WinME freely?

Any other ideas of how to exclude memory regions will be much appreciated.

Regards