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[Bug 1435210] [NEW] Ubuntu 15.04: Bad MTRR memory management

 

Public bug reported:

Hello,
in order to contribute to quality improvement of the new Ubuntu 15.04, I'm reporting a problem I found in this "beta" version - related to MTRR memory management (mtrr_gran_size/mtrr_chunk_size stuff).

If compared with Manjaro XFCE 0.9.0-pre4 edition (systemd, X.org server
1.17.1, kernel 1.19.1), it is quite obvious that there's definitely
something wrong with the way how Ubuntu handles 16GB of RAM (inside
BIOS, Intel graphics card is set to 256MB).

Asus optimus notebook N750JVT-4069H (Intel® Core™ i7-4700HQ; RAM 16GB;
Nvidia GeForce GT750M)

Manjaro dmesg output:

[    0.000000] DMI: ASUSTeK COMPUTER INC. N750JV/N750JV, BIOS N750JV.210 04/11/2014
[    0.000000] e820: update [mem 0x00000000-0x00000fff] usable ==> reserved
[    0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable
[    0.000000] AGP: No AGP bridge found
[    0.000000] e820: last_pfn = 0x42f200 max_arch_pfn = 0x400000000
[    0.000000] MTRR default type: uncachable
[    0.000000] MTRR fixed ranges enabled:
[    0.000000]   00000-9FFFF write-back
[    0.000000]   A0000-DFFFF uncachable
[    0.000000]   E0000-FFFFF write-protect
[    0.000000] MTRR variable ranges enabled:
[    0.000000]   0 base 0000000000 mask 7C00000000 write-back
[    0.000000]   1 base 0400000000 mask 7FE0000000 write-back
[    0.000000]   2 base 0420000000 mask 7FF8000000 write-back
[    0.000000]   3 base 0428000000 mask 7FFC000000 write-back
[    0.000000]   4 base 042C000000 mask 7FFE000000 write-back
[    0.000000]   5 base 042E000000 mask 7FFF000000 write-back
[    0.000000]   6 base 042F000000 mask 7FFFE00000 write-back
[    0.000000]   7 base 00C0000000 mask 7FC0000000 uncachable
[    0.000000]   8 base 00BFC00000 mask 7FFFC00000 uncachable
[    0.000000]   9 disabled
[    0.000000] PAT configuration [0-7]: WB  WC  UC- UC  WB  WC  UC- UC 
[    0.000000] e820: update [mem 0xbfc00000-0xffffffff] usable ==> reserved
[    0.000000] e820: last_pfn = 0xbf000 max_arch_pfn = 0x400000000
[    0.000000] Scanning 1 areas for low memory corruption

Ubuntu dmesg output:

[    0.000000] DMI: ASUSTeK COMPUTER INC. N750JV/N750JV, BIOS N750JV.210 04/11/2014
[    0.000000] e820: update [mem 0x00000000-0x00000fff] usable ==> reserved
[    0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable
[    0.000000] AGP: No AGP bridge found
[    0.000000] e820: last_pfn = 0x42f200 max_arch_pfn = 0x400000000
[    0.000000] MTRR default type: uncachable
[    0.000000] MTRR fixed ranges enabled:
[    0.000000]   00000-9FFFF write-back
[    0.000000]   A0000-DFFFF uncachable
[    0.000000]   E0000-FFFFF write-protect
[    0.000000] MTRR variable ranges enabled:
[    0.000000]   0 base 0000000000 mask 7C00000000 write-back
[    0.000000]   1 base 0400000000 mask 7FE0000000 write-back
[    0.000000]   2 base 0420000000 mask 7FF8000000 write-back
[    0.000000]   3 base 0428000000 mask 7FFC000000 write-back
[    0.000000]   4 base 042C000000 mask 7FFE000000 write-back
[    0.000000]   5 base 042E000000 mask 7FFF000000 write-back
[    0.000000]   6 base 042F000000 mask 7FFFE00000 write-back
[    0.000000]   7 base 00C0000000 mask 7FC0000000 uncachable
[    0.000000]   8 base 00BFC00000 mask 7FFFC00000 uncachable
[    0.000000]   9 disabled
[    0.000000] PAT configuration [0-7]: WB  WC  UC- UC  WB  WC  UC- UC  
[    0.000000] original variable MTRRs
[    0.000000] reg 0, base: 0GB, range: 16GB, type WB
[    0.000000] reg 1, base: 16GB, range: 512MB, type WB
[    0.000000] reg 2, base: 16896MB, range: 128MB, type WB
[    0.000000] reg 3, base: 17024MB, range: 64MB, type WB
[    0.000000] reg 4, base: 17088MB, range: 32MB, type WB
[    0.000000] reg 5, base: 17120MB, range: 16MB, type WB
[    0.000000] reg 6, base: 17136MB, range: 2MB, type WB
[    0.000000] reg 7, base: 3GB, range: 1GB, type UC
[    0.000000] reg 8, base: 3068MB, range: 4MB, type UC
[    0.000000] total RAM covered: 16110M
[    0.000000]  gran_size: 64K     chunk_size: 64K     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 64K     chunk_size: 128K     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 64K     chunk_size: 256K     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 64K     chunk_size: 512K     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 64K     chunk_size: 1M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 64K     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 64K     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 64K     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
[    0.000000]  gran_size: 64K     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 64K     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 64K     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 64K     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 64K     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 64K     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 64K     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
[    0.000000] *BAD*gran_size: 64K     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
[    0.000000]  gran_size: 128K     chunk_size: 128K     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 128K     chunk_size: 256K     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 128K     chunk_size: 512K     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 128K     chunk_size: 1M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 128K     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 128K     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 128K     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
[    0.000000]  gran_size: 128K     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 128K     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 128K     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 128K     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 128K     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 128K     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 128K     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
[    0.000000] *BAD*gran_size: 128K     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
[    0.000000]  gran_size: 256K     chunk_size: 256K     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 256K     chunk_size: 512K     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 256K     chunk_size: 1M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 256K     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 256K     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 256K     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
[    0.000000]  gran_size: 256K     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 256K     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 256K     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 256K     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 256K     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 256K     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 256K     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
[    0.000000] *BAD*gran_size: 256K     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
[    0.000000]  gran_size: 512K     chunk_size: 512K     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 512K     chunk_size: 1M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 512K     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 512K     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 512K     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
[    0.000000]  gran_size: 512K     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 512K     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 512K     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 512K     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 512K     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 512K     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 512K     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
[    0.000000] *BAD*gran_size: 512K     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
[    0.000000]  gran_size: 1M     chunk_size: 1M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 1M     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 1M     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 1M     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
[    0.000000]  gran_size: 1M     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 1M     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 1M     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 1M     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 1M     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 1M     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 1M     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
[    0.000000] *BAD*gran_size: 1M     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
[    0.000000]  gran_size: 2M     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 2M     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 2M     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
[    0.000000]  gran_size: 2M     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 2M     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 2M     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 2M     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 2M     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 2M     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
[    0.000000]  gran_size: 2M     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
[    0.000000] *BAD*gran_size: 2M     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
[    0.000000]  gran_size: 4M     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
[    0.000000]  gran_size: 4M     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
[    0.000000]  gran_size: 4M     chunk_size: 16M     num_reg: 10      lose cover RAM: 2M
[    0.000000]  gran_size: 4M     chunk_size: 32M     num_reg: 8      lose cover RAM: 2M
[    0.000000]  gran_size: 4M     chunk_size: 64M     num_reg: 8      lose cover RAM: 2M
[    0.000000]  gran_size: 4M     chunk_size: 128M     num_reg: 8      lose cover RAM: 2M
[    0.000000]  gran_size: 4M     chunk_size: 256M     num_reg: 8      lose cover RAM: 2M
[    0.000000]  gran_size: 4M     chunk_size: 512M     num_reg: 8      lose cover RAM: 2M
[    0.000000]  gran_size: 4M     chunk_size: 1G     num_reg: 8      lose cover RAM: 2M
[    0.000000]  gran_size: 4M     chunk_size: 2G     num_reg: 9      lose cover RAM: 2M
[    0.000000]  gran_size: 8M     chunk_size: 8M     num_reg: 10      lose cover RAM: 758M
[    0.000000]  gran_size: 8M     chunk_size: 16M     num_reg: 10      lose cover RAM: 6M
[    0.000000]  gran_size: 8M     chunk_size: 32M     num_reg: 8      lose cover RAM: 6M
[    0.000000]  gran_size: 8M     chunk_size: 64M     num_reg: 8      lose cover RAM: 6M
[    0.000000]  gran_size: 8M     chunk_size: 128M     num_reg: 8      lose cover RAM: 6M
[    0.000000]  gran_size: 8M     chunk_size: 256M     num_reg: 8      lose cover RAM: 6M
[    0.000000]  gran_size: 8M     chunk_size: 512M     num_reg: 8      lose cover RAM: 6M
[    0.000000]  gran_size: 8M     chunk_size: 1G     num_reg: 8      lose cover RAM: 6M
[    0.000000]  gran_size: 8M     chunk_size: 2G     num_reg: 9      lose cover RAM: 6M
[    0.000000]  gran_size: 16M     chunk_size: 16M     num_reg: 10      lose cover RAM: 254M
[    0.000000]  gran_size: 16M     chunk_size: 32M     num_reg: 8      lose cover RAM: 14M
[    0.000000]  gran_size: 16M     chunk_size: 64M     num_reg: 8      lose cover RAM: 14M
[    0.000000]  gran_size: 16M     chunk_size: 128M     num_reg: 8      lose cover RAM: 14M
[    0.000000]  gran_size: 16M     chunk_size: 256M     num_reg: 8      lose cover RAM: 14M
[    0.000000]  gran_size: 16M     chunk_size: 512M     num_reg: 8      lose cover RAM: 14M
[    0.000000]  gran_size: 16M     chunk_size: 1G     num_reg: 8      lose cover RAM: 14M
[    0.000000]  gran_size: 16M     chunk_size: 2G     num_reg: 9      lose cover RAM: 14M
[    0.000000]  gran_size: 32M     chunk_size: 32M     num_reg: 10      lose cover RAM: 142M
[    0.000000]  gran_size: 32M     chunk_size: 64M     num_reg: 8      lose cover RAM: 46M
[    0.000000]  gran_size: 32M     chunk_size: 128M     num_reg: 8      lose cover RAM: 46M
[    0.000000]  gran_size: 32M     chunk_size: 256M     num_reg: 8      lose cover RAM: 46M
[    0.000000]  gran_size: 32M     chunk_size: 512M     num_reg: 8      lose cover RAM: 46M
[    0.000000]  gran_size: 32M     chunk_size: 1G     num_reg: 8      lose cover RAM: 46M
[    0.000000]  gran_size: 32M     chunk_size: 2G     num_reg: 9      lose cover RAM: 46M
[    0.000000]  gran_size: 64M     chunk_size: 64M     num_reg: 10      lose cover RAM: 110M
[    0.000000]  gran_size: 64M     chunk_size: 128M     num_reg: 8      lose cover RAM: 110M
[    0.000000]  gran_size: 64M     chunk_size: 256M     num_reg: 8      lose cover RAM: 110M
[    0.000000]  gran_size: 64M     chunk_size: 512M     num_reg: 8      lose cover RAM: 110M
[    0.000000]  gran_size: 64M     chunk_size: 1G     num_reg: 8      lose cover RAM: 110M
[    0.000000]  gran_size: 64M     chunk_size: 2G     num_reg: 9      lose cover RAM: 110M
[    0.000000]  gran_size: 128M     chunk_size: 128M     num_reg: 8      lose cover RAM: 238M
[    0.000000]  gran_size: 128M     chunk_size: 256M     num_reg: 8      lose cover RAM: 238M
[    0.000000]  gran_size: 128M     chunk_size: 512M     num_reg: 8      lose cover RAM: 238M
[    0.000000]  gran_size: 128M     chunk_size: 1G     num_reg: 8      lose cover RAM: 238M
[    0.000000]  gran_size: 128M     chunk_size: 2G     num_reg: 9      lose cover RAM: 238M
[    0.000000]  gran_size: 256M     chunk_size: 256M     num_reg: 6      lose cover RAM: 494M
[    0.000000]  gran_size: 256M     chunk_size: 512M     num_reg: 6      lose cover RAM: 494M
[    0.000000]  gran_size: 256M     chunk_size: 1G     num_reg: 7      lose cover RAM: 494M
[    0.000000]  gran_size: 256M     chunk_size: 2G     num_reg: 8      lose cover RAM: 494M
[    0.000000]  gran_size: 512M     chunk_size: 512M     num_reg: 5      lose cover RAM: 750M
[    0.000000]  gran_size: 512M     chunk_size: 1G     num_reg: 7      lose cover RAM: 750M
[    0.000000]  gran_size: 512M     chunk_size: 2G     num_reg: 8      lose cover RAM: 750M
[    0.000000]  gran_size: 1G     chunk_size: 1G     num_reg: 3      lose cover RAM: 1774M
[    0.000000]  gran_size: 1G     chunk_size: 2G     num_reg: 3      lose cover RAM: 1774M
[    0.000000]  gran_size: 2G     chunk_size: 2G     num_reg: 3      lose cover RAM: 1774M
[    0.000000] mtrr_cleanup: can not find optimal value
[    0.000000] please specify mtrr_gran_size/mtrr_chunk_size
[    0.000000] e820: update [mem 0xbfc00000-0xffffffff] usable ==> reserved
[    0.000000] e820: last_pfn = 0xbf000 max_arch_pfn = 0x400000000
[    0.000000] Scanning 1 areas for low memory corruption

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: linux-image-3.19.0-9-generic 3.19.0-9.9 [modified: boot/vmlinuz-3.19.0-9-generic]
ProcVersionSignature: Ubuntu 3.19.0-9.9-generic 3.19.1
Uname: Linux 3.19.0-9-generic x86_64
ApportVersion: 2.16.2-0ubuntu4
Architecture: amd64
AudioDevicesInUse:
 USER        PID ACCESS COMMAND
 /dev/snd/controlC1:  aljosa     1824 F.... pulseaudio
 /dev/snd/controlC0:  aljosa     1824 F.... pulseaudio
CurrentDesktop: Unity
Date: Mon Mar 23 09:52:24 2015
HibernationDevice: RESUME=UUID=df42f272-c519-4323-977d-bb1fe697e7f0
InstallationDate: Installed on 2015-03-19 (3 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20150318)
MachineType: ASUSTeK COMPUTER INC. N750JV
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-9-generic.efi.signed root=UUID=da571e57-f1af-49b1-95ba-206e95c86cec ro quiet splash ipv6.disable=1 vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.19.0-9-generic N/A
 linux-backports-modules-3.19.0-9-generic  N/A
 linux-firmware                            1.143
SourcePackage: linux
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/11/2014
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: N750JV.210
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: N750JV
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: 1.0
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK COMPUTER INC.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrN750JV.210:bd04/11/2014:svnASUSTeKCOMPUTERINC.:pnN750JV:pvr1.0:rvnASUSTeKCOMPUTERINC.:rnN750JV:rvr1.0:cvnASUSTeKCOMPUTERINC.:ct10:cvr1.0:
dmi.product.name: N750JV
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK COMPUTER INC.

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: Confirmed


** Tags: amd64 apport-bug vivid

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https://bugs.launchpad.net/bugs/1435210

Title:
  Ubuntu 15.04: Bad MTRR memory management

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  Hello,
  in order to contribute to quality improvement of the new Ubuntu 15.04, I'm reporting a problem I found in this "beta" version - related to MTRR memory management (mtrr_gran_size/mtrr_chunk_size stuff).

  If compared with Manjaro XFCE 0.9.0-pre4 edition (systemd, X.org
  server 1.17.1, kernel 1.19.1), it is quite obvious that there's
  definitely something wrong with the way how Ubuntu handles 16GB of RAM
  (inside BIOS, Intel graphics card is set to 256MB).

  Asus optimus notebook N750JVT-4069H (Intel® Core™ i7-4700HQ; RAM 16GB;
  Nvidia GeForce GT750M)

  Manjaro dmesg output:

  [    0.000000] DMI: ASUSTeK COMPUTER INC. N750JV/N750JV, BIOS N750JV.210 04/11/2014
  [    0.000000] e820: update [mem 0x00000000-0x00000fff] usable ==> reserved
  [    0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable
  [    0.000000] AGP: No AGP bridge found
  [    0.000000] e820: last_pfn = 0x42f200 max_arch_pfn = 0x400000000
  [    0.000000] MTRR default type: uncachable
  [    0.000000] MTRR fixed ranges enabled:
  [    0.000000]   00000-9FFFF write-back
  [    0.000000]   A0000-DFFFF uncachable
  [    0.000000]   E0000-FFFFF write-protect
  [    0.000000] MTRR variable ranges enabled:
  [    0.000000]   0 base 0000000000 mask 7C00000000 write-back
  [    0.000000]   1 base 0400000000 mask 7FE0000000 write-back
  [    0.000000]   2 base 0420000000 mask 7FF8000000 write-back
  [    0.000000]   3 base 0428000000 mask 7FFC000000 write-back
  [    0.000000]   4 base 042C000000 mask 7FFE000000 write-back
  [    0.000000]   5 base 042E000000 mask 7FFF000000 write-back
  [    0.000000]   6 base 042F000000 mask 7FFFE00000 write-back
  [    0.000000]   7 base 00C0000000 mask 7FC0000000 uncachable
  [    0.000000]   8 base 00BFC00000 mask 7FFFC00000 uncachable
  [    0.000000]   9 disabled
  [    0.000000] PAT configuration [0-7]: WB  WC  UC- UC  WB  WC  UC- UC 
  [    0.000000] e820: update [mem 0xbfc00000-0xffffffff] usable ==> reserved
  [    0.000000] e820: last_pfn = 0xbf000 max_arch_pfn = 0x400000000
  [    0.000000] Scanning 1 areas for low memory corruption

  Ubuntu dmesg output:

  [    0.000000] DMI: ASUSTeK COMPUTER INC. N750JV/N750JV, BIOS N750JV.210 04/11/2014
  [    0.000000] e820: update [mem 0x00000000-0x00000fff] usable ==> reserved
  [    0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable
  [    0.000000] AGP: No AGP bridge found
  [    0.000000] e820: last_pfn = 0x42f200 max_arch_pfn = 0x400000000
  [    0.000000] MTRR default type: uncachable
  [    0.000000] MTRR fixed ranges enabled:
  [    0.000000]   00000-9FFFF write-back
  [    0.000000]   A0000-DFFFF uncachable
  [    0.000000]   E0000-FFFFF write-protect
  [    0.000000] MTRR variable ranges enabled:
  [    0.000000]   0 base 0000000000 mask 7C00000000 write-back
  [    0.000000]   1 base 0400000000 mask 7FE0000000 write-back
  [    0.000000]   2 base 0420000000 mask 7FF8000000 write-back
  [    0.000000]   3 base 0428000000 mask 7FFC000000 write-back
  [    0.000000]   4 base 042C000000 mask 7FFE000000 write-back
  [    0.000000]   5 base 042E000000 mask 7FFF000000 write-back
  [    0.000000]   6 base 042F000000 mask 7FFFE00000 write-back
  [    0.000000]   7 base 00C0000000 mask 7FC0000000 uncachable
  [    0.000000]   8 base 00BFC00000 mask 7FFFC00000 uncachable
  [    0.000000]   9 disabled
  [    0.000000] PAT configuration [0-7]: WB  WC  UC- UC  WB  WC  UC- UC  
  [    0.000000] original variable MTRRs
  [    0.000000] reg 0, base: 0GB, range: 16GB, type WB
  [    0.000000] reg 1, base: 16GB, range: 512MB, type WB
  [    0.000000] reg 2, base: 16896MB, range: 128MB, type WB
  [    0.000000] reg 3, base: 17024MB, range: 64MB, type WB
  [    0.000000] reg 4, base: 17088MB, range: 32MB, type WB
  [    0.000000] reg 5, base: 17120MB, range: 16MB, type WB
  [    0.000000] reg 6, base: 17136MB, range: 2MB, type WB
  [    0.000000] reg 7, base: 3GB, range: 1GB, type UC
  [    0.000000] reg 8, base: 3068MB, range: 4MB, type UC
  [    0.000000] total RAM covered: 16110M
  [    0.000000]  gran_size: 64K     chunk_size: 64K     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 64K     chunk_size: 128K     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 64K     chunk_size: 256K     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 64K     chunk_size: 512K     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 64K     chunk_size: 1M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 64K     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 64K     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 64K     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
  [    0.000000]  gran_size: 64K     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 64K     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 64K     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 64K     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 64K     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 64K     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 64K     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
  [    0.000000] *BAD*gran_size: 64K     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
  [    0.000000]  gran_size: 128K     chunk_size: 128K     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 128K     chunk_size: 256K     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 128K     chunk_size: 512K     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 128K     chunk_size: 1M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 128K     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 128K     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 128K     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
  [    0.000000]  gran_size: 128K     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 128K     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 128K     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 128K     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 128K     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 128K     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 128K     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
  [    0.000000] *BAD*gran_size: 128K     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
  [    0.000000]  gran_size: 256K     chunk_size: 256K     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 256K     chunk_size: 512K     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 256K     chunk_size: 1M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 256K     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 256K     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 256K     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
  [    0.000000]  gran_size: 256K     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 256K     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 256K     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 256K     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 256K     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 256K     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 256K     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
  [    0.000000] *BAD*gran_size: 256K     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
  [    0.000000]  gran_size: 512K     chunk_size: 512K     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 512K     chunk_size: 1M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 512K     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 512K     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 512K     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
  [    0.000000]  gran_size: 512K     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 512K     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 512K     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 512K     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 512K     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 512K     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 512K     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
  [    0.000000] *BAD*gran_size: 512K     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
  [    0.000000]  gran_size: 1M     chunk_size: 1M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 1M     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 1M     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 1M     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
  [    0.000000]  gran_size: 1M     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 1M     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 1M     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 1M     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 1M     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 1M     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 1M     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
  [    0.000000] *BAD*gran_size: 1M     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
  [    0.000000]  gran_size: 2M     chunk_size: 2M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 2M     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 2M     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
  [    0.000000]  gran_size: 2M     chunk_size: 16M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 2M     chunk_size: 32M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 2M     chunk_size: 64M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 2M     chunk_size: 128M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 2M     chunk_size: 256M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 2M     chunk_size: 512M     num_reg: 10      lose cover RAM: 0G
  [    0.000000]  gran_size: 2M     chunk_size: 1G     num_reg: 10      lose cover RAM: 0G
  [    0.000000] *BAD*gran_size: 2M     chunk_size: 2G     num_reg: 10      lose cover RAM: -1G
  [    0.000000]  gran_size: 4M     chunk_size: 4M     num_reg: 10      lose cover RAM: 8946M
  [    0.000000]  gran_size: 4M     chunk_size: 8M     num_reg: 10      lose cover RAM: 2M
  [    0.000000]  gran_size: 4M     chunk_size: 16M     num_reg: 10      lose cover RAM: 2M
  [    0.000000]  gran_size: 4M     chunk_size: 32M     num_reg: 8      lose cover RAM: 2M
  [    0.000000]  gran_size: 4M     chunk_size: 64M     num_reg: 8      lose cover RAM: 2M
  [    0.000000]  gran_size: 4M     chunk_size: 128M     num_reg: 8      lose cover RAM: 2M
  [    0.000000]  gran_size: 4M     chunk_size: 256M     num_reg: 8      lose cover RAM: 2M
  [    0.000000]  gran_size: 4M     chunk_size: 512M     num_reg: 8      lose cover RAM: 2M
  [    0.000000]  gran_size: 4M     chunk_size: 1G     num_reg: 8      lose cover RAM: 2M
  [    0.000000]  gran_size: 4M     chunk_size: 2G     num_reg: 9      lose cover RAM: 2M
  [    0.000000]  gran_size: 8M     chunk_size: 8M     num_reg: 10      lose cover RAM: 758M
  [    0.000000]  gran_size: 8M     chunk_size: 16M     num_reg: 10      lose cover RAM: 6M
  [    0.000000]  gran_size: 8M     chunk_size: 32M     num_reg: 8      lose cover RAM: 6M
  [    0.000000]  gran_size: 8M     chunk_size: 64M     num_reg: 8      lose cover RAM: 6M
  [    0.000000]  gran_size: 8M     chunk_size: 128M     num_reg: 8      lose cover RAM: 6M
  [    0.000000]  gran_size: 8M     chunk_size: 256M     num_reg: 8      lose cover RAM: 6M
  [    0.000000]  gran_size: 8M     chunk_size: 512M     num_reg: 8      lose cover RAM: 6M
  [    0.000000]  gran_size: 8M     chunk_size: 1G     num_reg: 8      lose cover RAM: 6M
  [    0.000000]  gran_size: 8M     chunk_size: 2G     num_reg: 9      lose cover RAM: 6M
  [    0.000000]  gran_size: 16M     chunk_size: 16M     num_reg: 10      lose cover RAM: 254M
  [    0.000000]  gran_size: 16M     chunk_size: 32M     num_reg: 8      lose cover RAM: 14M
  [    0.000000]  gran_size: 16M     chunk_size: 64M     num_reg: 8      lose cover RAM: 14M
  [    0.000000]  gran_size: 16M     chunk_size: 128M     num_reg: 8      lose cover RAM: 14M
  [    0.000000]  gran_size: 16M     chunk_size: 256M     num_reg: 8      lose cover RAM: 14M
  [    0.000000]  gran_size: 16M     chunk_size: 512M     num_reg: 8      lose cover RAM: 14M
  [    0.000000]  gran_size: 16M     chunk_size: 1G     num_reg: 8      lose cover RAM: 14M
  [    0.000000]  gran_size: 16M     chunk_size: 2G     num_reg: 9      lose cover RAM: 14M
  [    0.000000]  gran_size: 32M     chunk_size: 32M     num_reg: 10      lose cover RAM: 142M
  [    0.000000]  gran_size: 32M     chunk_size: 64M     num_reg: 8      lose cover RAM: 46M
  [    0.000000]  gran_size: 32M     chunk_size: 128M     num_reg: 8      lose cover RAM: 46M
  [    0.000000]  gran_size: 32M     chunk_size: 256M     num_reg: 8      lose cover RAM: 46M
  [    0.000000]  gran_size: 32M     chunk_size: 512M     num_reg: 8      lose cover RAM: 46M
  [    0.000000]  gran_size: 32M     chunk_size: 1G     num_reg: 8      lose cover RAM: 46M
  [    0.000000]  gran_size: 32M     chunk_size: 2G     num_reg: 9      lose cover RAM: 46M
  [    0.000000]  gran_size: 64M     chunk_size: 64M     num_reg: 10      lose cover RAM: 110M
  [    0.000000]  gran_size: 64M     chunk_size: 128M     num_reg: 8      lose cover RAM: 110M
  [    0.000000]  gran_size: 64M     chunk_size: 256M     num_reg: 8      lose cover RAM: 110M
  [    0.000000]  gran_size: 64M     chunk_size: 512M     num_reg: 8      lose cover RAM: 110M
  [    0.000000]  gran_size: 64M     chunk_size: 1G     num_reg: 8      lose cover RAM: 110M
  [    0.000000]  gran_size: 64M     chunk_size: 2G     num_reg: 9      lose cover RAM: 110M
  [    0.000000]  gran_size: 128M     chunk_size: 128M     num_reg: 8      lose cover RAM: 238M
  [    0.000000]  gran_size: 128M     chunk_size: 256M     num_reg: 8      lose cover RAM: 238M
  [    0.000000]  gran_size: 128M     chunk_size: 512M     num_reg: 8      lose cover RAM: 238M
  [    0.000000]  gran_size: 128M     chunk_size: 1G     num_reg: 8      lose cover RAM: 238M
  [    0.000000]  gran_size: 128M     chunk_size: 2G     num_reg: 9      lose cover RAM: 238M
  [    0.000000]  gran_size: 256M     chunk_size: 256M     num_reg: 6      lose cover RAM: 494M
  [    0.000000]  gran_size: 256M     chunk_size: 512M     num_reg: 6      lose cover RAM: 494M
  [    0.000000]  gran_size: 256M     chunk_size: 1G     num_reg: 7      lose cover RAM: 494M
  [    0.000000]  gran_size: 256M     chunk_size: 2G     num_reg: 8      lose cover RAM: 494M
  [    0.000000]  gran_size: 512M     chunk_size: 512M     num_reg: 5      lose cover RAM: 750M
  [    0.000000]  gran_size: 512M     chunk_size: 1G     num_reg: 7      lose cover RAM: 750M
  [    0.000000]  gran_size: 512M     chunk_size: 2G     num_reg: 8      lose cover RAM: 750M
  [    0.000000]  gran_size: 1G     chunk_size: 1G     num_reg: 3      lose cover RAM: 1774M
  [    0.000000]  gran_size: 1G     chunk_size: 2G     num_reg: 3      lose cover RAM: 1774M
  [    0.000000]  gran_size: 2G     chunk_size: 2G     num_reg: 3      lose cover RAM: 1774M
  [    0.000000] mtrr_cleanup: can not find optimal value
  [    0.000000] please specify mtrr_gran_size/mtrr_chunk_size
  [    0.000000] e820: update [mem 0xbfc00000-0xffffffff] usable ==> reserved
  [    0.000000] e820: last_pfn = 0xbf000 max_arch_pfn = 0x400000000
  [    0.000000] Scanning 1 areas for low memory corruption

  ProblemType: Bug
  DistroRelease: Ubuntu 15.04
  Package: linux-image-3.19.0-9-generic 3.19.0-9.9 [modified: boot/vmlinuz-3.19.0-9-generic]
  ProcVersionSignature: Ubuntu 3.19.0-9.9-generic 3.19.1
  Uname: Linux 3.19.0-9-generic x86_64
  ApportVersion: 2.16.2-0ubuntu4
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC1:  aljosa     1824 F.... pulseaudio
   /dev/snd/controlC0:  aljosa     1824 F.... pulseaudio
  CurrentDesktop: Unity
  Date: Mon Mar 23 09:52:24 2015
  HibernationDevice: RESUME=UUID=df42f272-c519-4323-977d-bb1fe697e7f0
  InstallationDate: Installed on 2015-03-19 (3 days ago)
  InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20150318)
  MachineType: ASUSTeK COMPUTER INC. N750JV
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-9-generic.efi.signed root=UUID=da571e57-f1af-49b1-95ba-206e95c86cec ro quiet splash ipv6.disable=1 vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-3.19.0-9-generic N/A
   linux-backports-modules-3.19.0-9-generic  N/A
   linux-firmware                            1.143
  SourcePackage: linux
  UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 04/11/2014
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: N750JV.210
  dmi.board.asset.tag: ATN12345678901234567
  dmi.board.name: N750JV
  dmi.board.vendor: ASUSTeK COMPUTER INC.
  dmi.board.version: 1.0
  dmi.chassis.asset.tag: No Asset Tag
  dmi.chassis.type: 10
  dmi.chassis.vendor: ASUSTeK COMPUTER INC.
  dmi.chassis.version: 1.0
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrN750JV.210:bd04/11/2014:svnASUSTeKCOMPUTERINC.:pnN750JV:pvr1.0:rvnASUSTeKCOMPUTERINC.:rnN750JV:rvr1.0:cvnASUSTeKCOMPUTERINC.:ct10:cvr1.0:
  dmi.product.name: N750JV
  dmi.product.version: 1.0
  dmi.sys.vendor: ASUSTeK COMPUTER INC.

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Follow ups

References