Author Topic: Plop creates errors while using memtest86  (Read 4743 times)

starbright

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Plop creates errors while using memtest86
« on: May 15, 2011, 15:27:44 PM »
Dear Plop developers. First thanks for this great tool. Anyhow, I found an issue, which has driven me almost crazy. Memtest86+, started via Plop from an USB stick, shows some errors at around 0.6MB.
I could verify this with 3 differen RAM modules, so I suspected first my Laptop.
But with the Ubuntu-Build-In memtest,  with memtest started from an USB CDROM (which can't be started afaik via plop) and started from the same USB stick via BIOS boot selection I don't have trouble. So I could isolate Plop as a reason for this errors.
That makes me a bit nervous about using plop an my general bootmanager. Can someone here explain, what is going on? Why is this happen and how is to handle this?
If you would like to look at the messages from memtest86+ see here:

http://forum.canardpc.com/threads/56618-Error-in-first-0.6MB-in-every-of-3-RAM-modulse-AMD-C-50-issue

Elmar

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Re: Plop creates errors while using memtest86
« Reply #1 on: May 15, 2011, 17:43:40 PM »
hi,
you don't have to be nervous, your ram is fine at that address. the technical background is:
memtest checks the whole ram except parts that are marked not to test because those memory parts are used by bios and similar, hardware memory i/o, the low memory and so on. when you look at the memory test range, then you will see something like 107K- (=begin testing at memory 107KB)  or 108K-  (=begin testing at 108K) or similar. i often explained that the boot manager has no space left to add anything because of some limitation and thats why the boot manager does not set the info that the address space that the usb driver is using is reserved space and must not be checked. so the space is checked and this causes the memory error of 2 bytes.

btw. i did now some tests. memtest does not aways start the memory test from the same ram address.
examles:

hard disk -> plop boot manager -> usb -> syslinux -> memtest: test starts at 108K -> the 2  bytes are not tested -> no memory error

network boot -> pxelinux -> memtest: test starts at too 108K -> the 2  bytes are not tested, regardless if the plop usb driver is loaded or not -> no memory error

floppy -> plop boot manager -> usb -> syslinux -> memtest: test starts at 107K -> the 2 bytes are tested -> report of 3 memory errors (one address is tested 2x)

regards
elmar

starbright

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Re: Plop creates errors while using memtest86
« Reply #2 on: May 15, 2011, 21:56:34 PM »
Thanks for the details - now I can sleep much better :)