Memtest address vs. BadRAM address

[fabricator4]

Aaaagh! I tried googling things like badram, mask etc and the first thing it offered up was this self same thread. You've got me curious so I shall keep looking, maybe for a manual for badram.

Does memtest+ always give the same errors in the exact same locations? This is important obviously, since if the failures are more random you can't hit a moving target.

Chris

[fabricator4]

OK, got it, I think. I went and had a look at the instructions for badram again. That prompted me to start memtest and have a look. Start memtest and press 'c' for configuration and then:

4 Error reporting mode
3 Badram patterns

Try that and see if it gives you useful information.

Chris

[vanrein]

Hello,

Following is the BadRAM documentation. It usually comes as part of the kernel patch, but inclusion in something as mainstream as Ubuntu probably means that you haven't seen it yet.


Good luck,

Rick "BadRAM" van Rein

http://rick.vanrein.org/linux/badram/

[vanrein]

The documentation for BadRAM is part of the kernel source, and from the sound of it is missing from the current Ubuntu release. I'll attach the original documentation so you can download, read and use it.

Enjoy,

Rick "BadRAM" van Rein

http://rick.vanrein.org/linux/badram

[fabricator4]

Thanks Rick, That file on your website was going to be my next stop. After sleep. Hopefully Dan will be able to get some useful data out of memtest86+ and get this to work. I really like the idea of being able to run Linux on an old laptop even though the fixed RAM is faulty. Chalk one up for the good guys.

If badram.txt is included with 10.04 release it's awfully hard to find. Another thing that's needed is a blow-by-blow instruction manual for people like Dan and myself who have never done this before. Maybe there's one out there, but it also is not easy to find.

Hopefully Dan will be able to get some useful information from memtest86+ and figure out how to pass this to grub.

Chris.

[Marturion]

OK, got it, I think. I went and had a look at the instructions for badram again. That prompted me to start memtest and have a look. Start memtest and press 'c' for configuration and then:

4 Error reporting mode
3 Badram patterns

Try that and see if it gives you useful information.

Chris

Thanks Chris. Yes, I'm aware of the badram error reporting mode in memtest+, but have you actually gotten it to work when encountering an error? As I originally stated, there appears to be a bug in memtest+ so the badram patterns aren't displayed properly. In my case only a blank red bar show up when the error(s) are encountered (at least in two versions of memtest+ I tried - 4.10 and 4.20.)

That's why I am asking how to translate the default memtest+ report into a badram pattern that will work in the GRUB_BADRAM boot parameter (in /etc/default/grub). If I could just use the badram report already available in memtest+, this problem would have a much easier solution

The documentation for BadRAM is part of the kernel source, and from the sound of it is missing from the current Ubuntu release. I'll attach the original documentation so you can download, read and use it.

Thanks Rick for BadRAM and for posting your badram.txt documentation here, I'll certainly look through that.

[fabricator4]

Unfortunately (or fortunately for me!) I don't have any bad RAM to test this on.

Maybe the data is right in front of you - the "Bad: ffff7bff" might be the mask you are looking for. We might just be mislead about the statement that memtest86+ is going to present us with an addr:mask result. If this is the case the "good" will be the compliment of the "bad" mask. You only need the "bad" mask for badram:

Failing address: 0000b609d50
Good: fffffbff
Bad: ffff7bff
ERR Bits: 00008000

11111111111111111111101111111111 = Good
11111111111111110111101111111111 = Bad
00000000000000001000000000000000 = ERR bits

Umm, is ERR bits the part you need, the "mask". It's all I can see at the moment...

Rick? Anyone?


Chris

[vanrein]

There was a request for a more detailed explanation than the kernel readme. This is a Linux Journal article that may help; note however that their layout shows 0<\#215>1234 instead of 0x1234.

http://www.linuxjournal.com/article/4489

Good luck,
Rick "BadRAM" van Rein

[bobblanchett]

The format of the badram part varies in length for x86 and x64 machines.

When you run memtest+ choose (c)onfigure then error formats then badram patterns
Then continue.

If memtest+ finds errors (and it may take hours or multiple runs) it will spit out a badram kernel parm in 32 bit format:
badram=0xbaseaddress,0xmemorymask

If one is or more modules are badly affected you may have several address/mask pairs as the value of the badram key.

eg
badram=0xdeadbeef,0xfffffffc

For x64 machines you must left pad the base address with 8 zeros and the mask with 8 f's.
as root, Edit /etc/default/grub then update-grub

Read badram.txt in the newer badram patches for details

Cheers,
Bob

For now, I'm going to attempt using memmap based on the information

here:
http://gquigs.blogspot.com/2009/01/b...ory-howto.html

and

here:
http://ubuntuforums.org/showthread.php?t=1342957

However, I would still be interested in the answer to my original question regarding Memtest+ and BadRAM if there's anyone who knows.

Thanks again everybody for your suggestions and friendly assistance.

[Dreamer Fithp Apprentice]

I'd love to know if OP ever got either of these approaches to work. For that matter has anyone figured how to get either to work for any Ubuntu? The text file the BADRAM gent attached was talking about LILO so it wasn't at all clear to me that it had any applicability to grub.

I got to this thread by using Ixquick/Google to try to find exactly what OP was asking for - how to get from memtest86 report nomenclature to BADRAM= nomenclature and I can't find anything on what I would have thought would be simple. It is hard to find any place where even the question is articulated clearly and I got no smell of an answer.

Is there any logical reason to prefer one approach over the other? I mean besides not being able to find any clear instructions on how to use one or both. I looks to me like in both cases this same fix will have to be done separately for each OS on the system. It would seem to me that the /etc/default/grub file containing the BADRAM= statement would have to be redone with any new installation but that the e approach might carry over if the new installation uses grub.

If there is any practical way to use either approach I sure would love to find clear instructions.

Edit added a few minutes later: I didn't notice this http://ubuntuforums.org/showthread.php?t=1342957 , post # 2 before posting. It's a third approach. Post is 2 years old but the statement sisco is writing about is still there in /etc/default/grub with a pair of empty quotation marks waiting to be filled. So I filled it thus:

GRUB_CMDLINE_LINUX="65M\$570M"

Following sisco311's instructions I did "sudo update-grub" and confirmed that a change had been made in /boot/grub/grub.cfg. I rebooted and haven't crashed. But since this doesn't take effect, assuming it works, until after I boot this OS, memtest can't test it. So how do I know if it worked?