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I have a stick of bad memory (the computer randomly segfaults an it gives memtest86+ errors, picture of output at bottom). As I would like this computer to be working while I work on getting new ram, I would like to use the functionality on grub2 to mask off bad memory. (How to blacklist a correct bad RAM sector according to MemTest86+ error indication? uses a different method which involves passing arguments to the kernel to do the same thing)

Following the directions from the bottom of this page and the comment in /etc/defaults/grub I added the following line to /etc/defaults/grub

GRUB_BADRAM="0xbfc90044,0xffff80c4,0xb0490444,0xf77f84ec,0xb2490444,0xf27facc4,0xb0492864,0xf07faef4,0xb0490044,0xfd7f91e4,0xb0492144,0xff7fa1c4,0xb0490244,0xf37fe2c4,0xb0494044,0xf3ffc0e4,0xb0493464,0xf17fb4e4,0xb0490044,0xff7fa0c4"

which after running update-grub added 

badram 0xbfc90044,0xffff80c4,0xb0490444,0xf77f84ec,0xb2490444,0xf27facc4,0xb0492864,0xf07faef4,0xb0490044,0xfd7f91e4,0xb0492144,0xff7fa1c4,0xb0490244,0xf37fe2c4,0xb0494044,0xf3ffc0e4,0xb0493464,0xf17fb4e4,0xb0490044,0xff7fa0c4

to /boot/grub/grub.cfg which seems to correctly match the command line arguments specified here.

However, when I re-boot grub does not load, there is just a blank screen. Booting with a live-disc, commenting out the badram line in /boot/grub/grub.cfg allowed me to boot again (but I still have the bad memory un-masked).

I am pretty sure I copied the addresses and masks correctly (had an office mate read the picture to me after I copied it and then I read the file back to them while they were looking at the picture) so I assume I have done something wrong with the formatting, but I do not know what.

memtest86+ output

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  • Isn't this the same Q as here? How to blacklist a correct bad RAM sector according to MemTest86+ error imdocation? Commented Oct 25, 2013 at 23:56
  • @slm same goal, but it uses a kernel argument (memmap) rather than instructions to grub. Commented Oct 26, 2013 at 0:30
  • OK, that what I thought but I wanted you to double check. Commented Oct 26, 2013 at 0:33
  • I did see that thread, probably should have made note of that. Having grub do it seems more elegant some how. Commented Oct 26, 2013 at 0:35

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To use badram option you need patched kernel, and latest patch avaliable only for 2.6.28.

I think you use more recent kernel without that patch, and this is the cause of black screen.

You should use memmap option instead of badram.

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    no, this is passing the information to grub not to the kernel. Commented Oct 25, 2013 at 18:47
  • Further, the issue happens before grub has loaded, thus the kernel is not involved at all. Commented Oct 25, 2013 at 18:55

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