[Sun Mar 1 07:51:40 2020] MTRR default type: uncachable [Sun Mar 1 07:51:40 2020] MTRR fixed ranges enabled: [Sun Mar 1 07:51:40 2020] MTRR variable ranges enabled: [Sun Mar 1 07:51:40 2020] pmd_set_huge: Cannot satisfy [mem 0xf8000000-0xf8200000] with a huge-page mapping due to MTRR override.
Noticed these messages just now, after I've rebooted the server several days ago.
Might be relevant:
enable_mtrr_cleanup found in kernel parameters, I quote:
The kernel tries to adjust MTRR layout from continuous to discrete, to make X server driver able to add WB entry later. This parameter enables that.
I don't understand the above, but I feel I should mention the hardware:
It's an older piece from Dell, PowerEdge T20 with CPU (and iGPU) Intel Xeon E3-1225 v3 3.2GHz, 8MB cache, 4C/4T, full specs on Intel's Ark + it has 32 GB of DDR3 in UDIMM.
All I managed to find on MTRR (Memory Type Range Register) is on Wikipedia, sadly I do not understand much of this either. Any hints in more or less layman terms? Should I even care for that
dmesg message on my Debian 10?
As opposed to the server above, here is relevant part mentioning MTRR on hardware being my newer laptop also from Dell, Inspiron 15, 32 GB of DDR4 in SO-DIMM:
[Sat Mar 7 10:00:42 2020] MTRR default type: write-back [Sat Mar 7 10:00:42 2020] MTRR fixed ranges enabled: [Sat Mar 7 10:00:42 2020] MTRR variable ranges enabled:
I can see little difference, maybe there is none in real-word application... maybe there is.