Gentoo Archives: gentoo-user

From: tuxic@××××××.de
To: Gentoo <gentoo-user@l.g.o>
Subject: [gentoo-user] New motherboard, new CPU => MTRR problems
Date: Wed, 25 Mar 2020 06:09:17
Message-Id: 20200325060904.dq5a33gk5yy44jlk@solfire

the hardware consists of:
AMD Ryzen 5 3600
MSI Tomahawk MAX
32GB RAM (Corsair Venegeance 2x16GB,dual channel)
NVidia RTX 2060 SUPER

cat /proc/mtrr gives me

reg00: base=0x000000000 (    0MB), size= 2048MB, count=1: write-back
reg01: base=0x080000000 ( 2048MB), size= 1024MB, count=1: write-back
reg02: base=0x0c0000000 ( 3072MB), size=  512MB, count=1: write-back
reg03: base=0x0dc0a0000 ( 3520MB), size=   64KB, count=1: uncachable

-> there is a chunk of uncachable memory

I activated the sanitizer in the kernel and in kernel I found

[    0.000000] MTRR default type: uncachable
[    0.000000] MTRR fixed ranges enabled:
[    0.000000]   00000-9FFFF write-back
[    0.000000]   A0000-BFFFF write-through
[    0.000000]   C0000-FFFFF write-protect
[    0.000000] MTRR variable ranges enabled:
[    0.000000]   0 base 000000000000 mask FFFF80000000 write-back
[    0.000000]   1 base 000080000000 mask FFFFC0000000 write-back
[    0.000000]   2 base 0000C0000000 mask FFFFE0000000 write-back
[    0.000000]   3 base 0000DC0A0000 mask FFFFFFFF0000 uncachable
[    0.000000]   4 disabled
[    0.000000]   5 disabled
[    0.000000]   6 disabled
[    0.000000]   7 disabled
[    0.000000]  gran_size: 64K 	chunk_size: 64M 	num_reg: 4  	lose cover RAM: 0G

So I set the kernel cmdline to:
BOOT_IMAGE=/vmlinuz-5051101-64-RT root=/dev/sda11 ro console=tty0 console=ttyS0,115200n8 enable_mtrr_cleanup mtrr_spare_reg_nr=1 mtrr_gran_size=64K mtrr_chunk_size=64M

rebooted and found the same problem unchanged.

The Gentoo docs says, that there is a BIOS setting - probably under
"CPU" - which I should set from continuos to separated...but nowaday
BIOSse may look like a part of a Science Fiction moview...but I can
find those setting neither under "EZ" (for "easy settings" not under
"advanced" (for "danger ahead - you may screw up your board").

The bios of the board is not the top is the previous
The changelog of the newest BIOS does not mention anything I would
see as related to the mtrr problem...

Background: The RTX 2060 SUPER was intended to replace the
old GTX 960 I had....but the "BMW27" benchmark with Blender
is slower than with the GTX 960...

How can I fix the mtrr problem (and the performance problem
of the graphics card, is related) ?

Thanks a lot in advance for any help!


Subject Author
Re: [gentoo-user] New motherboard, new CPU => MTRR problems "J. Roeleveld" <joost@××××××××.org>