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[solved] Using memmap to reserve multiple memory ranges
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pjp
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PostPosted: Thu Dec 26, 2024 3:10 am    Post subject: [solved] Using memmap to reserve multiple memory ranges Reply with quote

After running memtest, I appear to have two memory ranges that are bad. Presuming I'm not mistaken, the subsequent question is how to mask both ranges.

Transcribed:
Code:
Tst  Pass   Failing Address           Good       Bad     Err-Bits  Count  CPU
---  ----  ------------------------  --------  --------  --------  -----  ----
  7     1  002a0a1d670 - 10,762.8MB  dfffffff  dffffffd  00000002      1    0
  7     1  002a0a1d8b0 - 10,762.8MB  ffffffdf  ffffffd2  00000002      2    0
  7     1  002a0a1d9b0 - 10,762.8MB  fffffdff  fffffdfd  00000002      3    0

  7     1  002e0a1d650 - 11,786.8MB  dfffffff  dffffffd  00000002      4    0
  7     1  002e0a1d890 - 11,786.8MB  ffffffdf  ffffffdd  00000002      5    0
  7     1  002e0a1d990 - 11,786.8MB  fffffdff  fffffdfd  00000002      6    0
Each "segment" appears separated by about 1bn bytes, so two ranges seem appropriate.

The first three: 002a0a1d670, 002a0a1d8b0, 002a0a1d9b0 are in the 4k block: 002A0A1D000 - 002A0A1E000

While the second three: 002e0a1d650, 002e0a1d890, 002e0a1d990 are in the 4k block: 002E0A1D000 - 002E0A1E000


For memmap= it seems that multiple ranges require multiple memmap= declarations.

So, without an actual root= line available (memtest86 is still running), this should be the solution:
Code:
root=UUID=... memmap=4K\$0x002A0A1D000 memmap=4K\$0x002E0A1D000
It seems grub doesn't like $, and escaping is required. Exactly how isn't clear, but I think I came across two references to \\\$.

Did I calculate the memory ranges incorrectly? Does the root= parameter seem OK? Anything else?
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pjp
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PostPosted: Thu Dec 26, 2024 5:21 am    Post subject: Reply with quote

I had an error in the memmap= entries. I forgot the leading 0x.

I had tried \\\$0x2... and that failed. There were some messages I didn't note carefully. As it was non-responsive to keyboard input, I considered it to be "locked up."

I updated the above post with the entries that seem to have worked. To verify:
Code:
$ dmesg |grep -i reserv |grep user: |grep -i 02[ae]0a1d00
[    0.000000] user: [mem 0x00000002a0a1d000-0x00000002a0a1dfff] reserved
[    0.000000] user: [mem 0x00000002e0a1d000-0x00000002e0a1dfff] reserved


I ought to see if there's a chance re-seating the memory would help, or moving the 3rd 4GB stick to another slot, but not today. 22hrs+ of memtest only found the referenced errors on the first pass. After six passes, no new errors were found.

Memory is fairly cheap though, so if it is RAM, maybe an upgrade from 4x4GB to 2x16GB.

I'm also revisiting a Zen build. Cases are mostly awful. :(
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