IOMMU to ENABLED in the bios

[wintpe]

This is an information message realy rather that a request for help.
its not a bug, but it might give a few people a headache

gigabyte AMD boards have an option

IOMMU in the bios

by default it is disabled.

the realtek 8111E and the black usb ports will behave like they have noise on them

for example TX errors on the nic, and keyboards doing there own thing.
this leads to inability to get dhcp to get dns servers or any combination around dhcp and
comunication errors.

other symptoms clonezilla cd rebooting over and over, mageia dvd booting, loading the ramdisk loader and then freezing int freezing during initial boot if install, and then trying a windows XP install and it works like a charm


until that is you enable IOMMU in the bios

from the jist i picked up in forums, some put this down to gigabytes
lack of even an existance of linux, others to all sorts of imotive reasons.

but this was a system i have built for a relation, based on the AMD FX-6300 6-Core FX Series
mounted on a Gbyte GA-970A-DS3P Motherboard with 1GB Zotac GT210 Synergy DDR3
4GB 2x2GB CMX4GX3M2B1600C9.

once IOMMU was enabled mageia 3 64 DVD release (KDE) behaves as we all expect it to.

without it i was starting to think noise on power supply, bad regulators, and planning to exchange the motherboard, i was a night and day change in stability

the thread that helped me, posted here to give credit , where credit is due.

http://forum.giga-byte.co.uk/index.php?topic=8129.0

heres another thread which backs up one of the symptoms

http://ubuntuforums.org/showthread.php?t=2183078

What is IOMMU, something to do with amd virtualisation in the chipset.

why i need this on a desktop that im not currently using virt with, just to make it stable i dont know
right now.

hope this helps others

regards peter

[doktor5000]

changed to sticky

[wintpe]

if any of you encounter this after enabling iommu the usb 3 ports stop working.
A further fix is required with
iommu=soft appended to the kernel line.

regards peter

[wintpe]

I wanted to add an update to this. although not related to the original post, my own 990FX based board with a phenom II 1100T
now requires IOMMU to be enabled in the bios as of the release of the 3.10.44 kernel.

without it the USB ports simply dont work.

obviously the use of IOMMU by the kerel on AMD 990 , 890 and other chipsets is becoming a requirment.

Not all mainboards offer it in the BIOS, hopefully they wont have the same issues.

regards peter

[wintpe]

If you get errors at the very start of the boot on AMD 990 based boards, about disabling iommu try adding the ivrs_io* entries to your kernel line, like i have
this corrects the motherboards wrong values in some older bioses like the asus crosshair vformula.
and makes iommu work

Code: Select all

title linux
kernel (hd0,0)/boot/vmlinuz BOOT_IMAGE=linux root=UUID=64908e9e-a9d0-42d3-9071-216867feaec8 nokmsboot splash quiet ivrs_ioapic[7]=00:14.0 ivrs_ioapic[8]=00:00.1 resume=UUID=dc0cbfe4-6ac0-4bbf-b247-ceb7ec75a34b vga=788
root (hd0,0)
initrd /boot/initrd.img


regards peter