Hello, I use SUSE 10.0 with all updates and actual kernel 2.6.13-15.8 as provided from SUSE (just self compiled to optimize for Athlon64, SMP, and HZ=100), with an Asus A8N-E motherboard, and an Athlon64x2 CPU. This host is used with VMware GSX server running 6 Linux client and one Windows client host. There's a SW-RAID1 using 2 SATA HDs. When we wanted to install a new client, and inserted a DVD into the PC, it behaved like on drugs, showing the following output in /var/log/warn: Feb 28 15:19:30 baum kernel: rtc: lost some interrupts at 256Hz. Feb 28 15:19:47 baum kernel: rtc: lost some interrupts at 256Hz. Feb 28 15:20:26 baum kernel: rtc: lost some interrupts at 256Hz. Feb 28 15:20:45 baum kernel: PCI-DMA: Out of IOMMU space for 225280 bytes at device 0000:00:08.0 Feb 28 15:20:45 baum kernel: end_request: I/O error, dev sda, sector 12248446 Feb 28 15:20:45 baum kernel: Operation continuing on 1 devices Feb 28 15:20:45 baum kernel: PCI-DMA: Out of IOMMU space for 221184 bytes at device 0000:00:08.0 Feb 28 15:20:45 baum kernel: end_request: I/O error, dev sdb, sector 12248454 Feb 28 15:20:45 baum kernel: printk: 118 messages suppressed. Feb 28 15:20:45 baum kernel: Buffer I/O error on device md0, logical block 1004928 Feb 28 15:20:45 baum kernel: lost page write due to I/O error on md0 Feb 28 15:20:45 baum kernel: Buffer I/O error on device md0, logical block 1004929 Feb 28 15:20:45 baum kernel: lost page write due to I/O error on md0 After that, the SW RAID stopped it's work, some VMware clients crashed and so on. Not a good situation. I found this in dmesg: CPU 0: aperture @ b6c6000000 size 32 MB Aperture from northbridge cpu 0 too small (32 MB) No AGP bridge found Your BIOS doesn't leave a aperture memory hole Please enable the IOMMU option in the BIOS setup This costs you 64 MB of RAM Mapping aperture over 65536 KB of RAM @ 8000000 PCI-DMA: Disabling AGP. PCI-DMA: aperture base @ 8000000 size 65536 KB PCI-DMA: Reserving 64MB of IOMMU area in the AGP aperture The problem is, it's an ASUS A8N-E, and doesn't have AGP but PCI-Express - and therefore no more BIOS setting for the AGP aperture size. The kernel set that IOMMU to 64MB, but it still seems to small. There's a kernel boot option "iommu=...", but using "iommu=off" lead to a frozen system during boot, and "iommu=128M" didn't boot at all. I found a message from Andi Kleen of SUSE suggesting using "iommu=memaper=3", and that helped - at least until now. I just wanted to say thank you for that, and document this fact here for others possibly running into the same problem. Output from the kernel source script "sh scripts/ver_linux": Linux baum 2.6.13-15.8-ZMI #1 SMP Tue Feb 28 16:07:49 CET 2006 x86_64 x86_64 x86_64 GNU/Linux Gnu C 4.0.2 Gnu make 3.80 binutils 2.16.91.0.2 util-linux 2.12q mount 2.12q module-init-tools 3.2-pre8 e2fsprogs 1.38 jfsutils 1.1.8 reiserfsprogs 3.6.18 reiser4progs line xfsprogs 2.6.36 Linux C Library 2.3.5 Dynamic linker (ldd) 2.3.5 Linux C++ Library 6.0.6 Procps 3.2.5 Net-tools 1.60 Kbd 1.12 Sh-utils 5.3.0 udev 068 Modules Loaded vmnet vmmon joydev af_packet iptable_filter ip_tables button battery ac ipv6 ide_cd cdrom sundance mii shpchp pci_hotplug generic ehci_hcd i2c_nforce2 ohci_hcd usbcore i2c_core dm_mod reiserfs raid1 fan thermal processor sg sata_nv libata amd74xx sd_mod scsi_mod ide_disk ide_core -- // Michael Monnerie, Ing.BSc --- it-management Michael Monnerie // http://zmi.at Tel: 0660/4156531 Linux 2.6.11 // PGP Key: "lynx -source http://zmi.at/zmi2.asc | gpg --import" // Fingerprint: EB93 ED8A 1DCD BB6C F952 F7F4 3911 B933 7054 5879 // Keyserver: www.keyserver.net Key-ID: 0x70545879