Linux & ACPI on ASUS P5B

Ok, so I had a lot of headache due to this and a hard time finding info online. Well, not info per se really; I read a lot of posts from people having the same problem. But there was not much to be found when it came to solutions, workarounds, a HOWTO, or such. The best advice people could come up with was “that sucks, buy another mobo”. So, pretty useless info, IMO. Finally I managed to find out how to fix this, and with a (the?) solution at hand, this page was created to share the info with other people experiencing the same problem.

Problem

You boot you nice Linux system on an ASUS P5B motherboard.
You have made sure that you have the latest BIOS version.
You have enabled ACPI support in BIOS, tried with and without the ACPI 2.0 option, SpeedStep is enabled, C1E Support is enabled, etc.
But the ACPI functions (SpeedStep, poweroff at halt, etc.) do not work!
You search for ACPI in dmesg and find:

[ 0.000000] BIOS-e820: [mem 0x000000007ff90000-0x000000007ff9dfff] ACPI
[ 0.000000] BIOS-e820: [mem 0x000000007ff9e000-0x000000007ffdffff] ACPI NVS
[ 0.000000] ACPI: RSDP 00000000000fa9b0 00024 (v02 ACPIAM)
[ 0.000000] ------------[ cut here ]------------
[ 0.000000] WARNING: CPU: 0 PID: 0 at /build/linux-SMWX37/linux-3.12.9/arch/x86/mm/ioremap.c:536 __early_ioremap+0xe2/0x1ab()
[ 0.000000] Modules linked in:
[ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 3.12-0.bpo.1-amd64 #1 Debian 3.12.9-1~bpo70+1
[ 0.000000] Hardware name: System manufacturer System Product Name/P5B, BIOS 2104 03/09/2009
[ 0.000000] 0000000000000000 ffffffff816f12d0 ffffffff814be0b3 0000000000000000
[ 0.000000] ffffffff810603a7 0000000000000000 000000007ff90100 000000007ff90000
[ 0.000000] 8000000000000563 00000000000eabbb ffffffff818d88af 0000000000000024
[ 0.000000] Call Trace:
[ 0.000000] [<ffffffff814be0b3>] ? dump_stack+0x41/0x51
[ 0.000000] [<ffffffff810603a7>] ? warn_slowpath_common+0x87/0xc0
[ 0.000000] [<ffffffff818d88af>] ? __early_ioremap+0xe2/0x1ab
[ 0.000000] [<ffffffff818d8b49>] ? early_ioremap+0x10/0x12
[ 0.000000] [<ffffffff818f8ad9>] ? acpi_tb_parse_root_table+0xad/0x2b4
[ 0.000000] [<ffffffff818f6a62>] ? acpi_table_init+0x17/0x99
[ 0.000000] [<ffffffff818cf2a4>] ? acpi_boot_table_init+0x1b/0x81
[ 0.000000] [<ffffffff818c7631>] ? setup_arch+0xb7b/0xcc0
[ 0.000000] [<ffffffff814bb14f>] ? printk+0x4f/0x54
[ 0.000000] [<ffffffff818c0b74>] ? start_kernel+0xce/0x435
[ 0.000000] [<ffffffff818c0120>] ? early_idt_handlers+0x120/0x120
[ 0.000000] [<ffffffff818c06d9>] ? x86_64_start_kernel+0x10e/0x11d
[ 0.000000] ---[ end trace 171789a7326777e3 ]---
[ 0.000000] ACPI: \xffffffa8<?? 000000007ff90100 EABBAA8A (v135 \xffffffbe*\xffffffe4\xffffffaa\xffffffeaz !ge\xfffffff5\xffffffce\xfffffff0d? 21888E54 k?\xfffffffa\xffffffbf D44B68DF)
[ 0.000000] ------------[ cut here ]------------
[ 0.182998] PM: Registering ACPI NVS region [mem 0x7ff9e000-0x7ffdffff]
[ 0.184082] ACPI: Interpreter disabled.
[ 0.185660] pci 0000:00:1f.0: quirk: [io 0x0800-0x087f] claimed by ICH6 ACPI/GPIO/TCO
[ 0.190025] pnp: PnP ACPI: disabled
[ 4.733499] ACPI Exception: AE_BAD_PARAMETER, Thread 2072557632 could not acquire Mutex [0x1] (20130725/utmutex-285)
[ 4.733637] ACPI Exception: AE_BAD_PARAMETER, Thread 2072557632 could not acquire Mutex [0x1] (20130725/utmutex-285)
[ 4.733750] ACPI Exception: AE_BAD_PARAMETER, Thread 2072557632 could not acquire Mutex [0x1] (20130725/utmutex-285)
[ 4.772750] ACPI Exception: AE_BAD_PARAMETER, Thread 2075713728 could not acquire Mutex [0x1] (20130725/utmutex-285)
[ 11.760955] input: ACPI Virtual Keyboard Device as /devices/virtual/input/input11

Ok, so something is clearly not ok. But what?

Solution

Disable the Memory Remap Feature in BIOS.

Most probably you have enabled the Memory Remap Feature under North Bridge Chipset Configuration in BIOS. And most probably you did so since you have more than 3008 MB of RAM and want to use it. Well, disable the Memory Remap Feature, save and reboot you Linux system in order to enjoy working ACPI functionality. You will have to choose between only 3008 MB RAM or ACPI functionality, unfortunately.

Please feel free to e-mail me if you have positive comments or concrete suggestions of changes or updates.