Ciao Gianluca, I have had problems with IOMMU in SL4 too. You can set IOMMU space with a kernel parameter. Try giving the kernel the parameter iommu=memaper=3 at the grub command line. You can change the number to change the amount of space you want allocated to the IOMMU. James. -----Original Message----- From: [log in to unmask] [mailto:[log in to unmask]] On Behalf Of Gianluca Guidi Sent: 08 May 2007 13:37 To: [log in to unmask] Subject: Problem with IOMMU Hi all, I tried to install SL 4.2 64bit in my Dell Inspiron 6400 Core 2 Duo T5600 (1.83GHz, 667 MHz FSB 2MB L2 cache) 2048 ( MB(1024x2) 667 MHz DDR2 SDRAM but the process stopped during the post-istallation process with the message: Kernel panic: net syncing: PCI-DMA: high address but no IOMMU Actually, I cannot find any IOMMU in my bios. Some ideas? thanks GM Guidi