BIOS bug: CPU MTRRs don't cover all of memory

[didwah]

Ok I have been having trouble getting Ubuntu 8.04 64 bit Server edition to run well on these specs, So I tried Server Edition 8.10 64bit. While this did run better I was only able to see a reduced amount of RAM.

Hardware is as follows:

MOBO: MSI G31M3-L
RAM: Kingston DDR2 4(2x2G)PC6400 800Mhz – KVR800D2N5K2/4G RAM
CPU: Intel ATX E8400 CORE 2 DUO /3.0GHz/6MB/1333FSB/LGA775
HD: 2 x Western Digital 320G SATAII 7200 rpm HDD(16Mb Cache)
DVD: LG H22NS30 SATA 22X+- Super Multi DVD Rewriter

dmesg gave this output. I will also attach the full dmesg out put. The only other thing I can think of is the BIOS with 4 GB of RAM inserted says there is actually 4864MB of RAM!!! This is most likely were the issue lay I think.

[ 0.000000] WARNING: BIOS bug: CPU MTRRs don't cover all of memory, losing 768MB of RAM.
[ 0.000000] ------------[ cut here ]------------
[ 0.000000] WARNING: at /build/buildd/linux-2.6.27/arch/x86/kernel/cpu/mtrr/main.c:1558 mtrr_trim_uncached_memory+0x397/0x3b4()
[ 0.000000] Modules linked in:
[ 0.000000] Pid: 0, comm: swapper Not tainted 2.6.27-7-server #1
[ 0.000000]
[ 0.000000] Call Trace:
[ 0.000000] [<ffffffff8024e9b4>] warn_on_slowpath+0x64/0x90
[ 0.000000] [<ffffffff804ffa66>] ? printk+0x6c/0x6e
[ 0.000000] [<ffffffff80727e5e>] ? e820_update_range_map+0x16/0x11a
[ 0.000000] [<ffffffff8072aa5f>] ? x86_get_mtrr_mem_range+0x16c/0x2ee
[ 0.000000] [<ffffffff8072badf>] mtrr_trim_uncached_memory+0x397/0x3b4
[ 0.000000] [<ffffffff80726c25>] setup_arch+0x5b7/0x8d2
[ 0.000000] [<ffffffff80271827>] ? clockevents_register_notifier+0x47/0x60
[ 0.000000] [<ffffffff8071eb77>] start_kernel+0x75/0x3b5
[ 0.000000] [<ffffffff8071e2b9>] x86_64_start_reservations+0x99/0xb6
[ 0.000000] [<ffffffff8071e3de>] x86_64_start_kernel+0xe0/0xef
[ 0.000000] [<ffffffff8071e140>] ? early_idt_handler+0x0/0x72
[ 0.000000]
[ 0.000000] ---[ end trace 4eaa2a86a8e2da22 ]---
[ 0.000000] update e820 for mtrr
[ 0.000000] modified physical RAM map:
[ 0.000000] modified: 0000000000000000 - 000000000009fc00 (usable)
[ 0.000000] modified: 000000000009fc00 - 00000000000a0000 (reserved)
[ 0.000000] modified: 00000000000e0000 - 0000000000100000 (reserved)
[ 0.000000] modified: 0000000000100000 - 00000000cf6a0000 (usable)
[ 0.000000] modified: 00000000cf6a0000 - 00000000cf6ae000 (ACPI data)
[ 0.000000] modified: 00000000cf6ae000 - 00000000cf6f0000 (ACPI NVS)
[ 0.000000] modified: 00000000cf6f0000 - 00000000cf6fe000 (reserved)
[ 0.000000] modified: 00000000fee00000 - 00000000fee01000 (reserved)
[ 0.000000] modified: 00000000fff80000 - 0000000130000000 (reserved)
[ 0.000000] last_pfn = 0xcf6a0 max_arch_pfn = 0x3ffffffff
[ 0.000000] init_memory_mapping
[ 0.000000] 0000000000 - 00cf600000 page 2M
[ 0.000000] 00cf600000 - 00cf6a0000 page 4k
[ 0.000000] kernel direct mapping tables up to cf6a0000 @ 8000-e000
[ 0.000000] last_map_addr: cf6a0000 end: cf6a0000
[ 0.000000] RAMDISK: 3779f000 - 37fef8c5
[ 0.000000] DMI present.

Please let me know if you require any more info.

Cheers

Didwah

[Leann Ogasawara (leannogasawara)]

Hi didwah,

Just curious if you've checked if there is a BIOS update for you system? Care to also attach your dmidecode information:

sudo dmidecode > dmidecode.log

[didwah (petercdee)]

Hi Leann

Thank you for your reply. I have since gone and purchased a different brand of mATX intel G31 board (Gigabyte GA-G31M-S2L) and this has solved the issue. It looks like it is definitely a BIOS bug as the BIOS is reporting the wrong amount of memory to the OS. I will see if I can find an update for the board and get back to you.

I don't mind if you close this bug report.

Thank you for your help.

Cheers

Didwah

[Leann Ogasawara (leannogasawara)]

Thanks didwah. Lets go ahead and close this out as it appears to be a BIOS issue. Thanks.