Ater some years. I am figure out that on these machime was hardware deffect. Hardware is not stable. > > >"IRQ problem dom0 xen4.5-amd64" >i have mothrboard geforce 6100pm-m2(v3.0) latest bios and athtlon 64 x2 5000+ cpu >Mothrboard based on nforce 430 chipset >if in bios enabled apic mode. Xen boot stops on trying to load dom0 kernel (gentoo kernel v4.5 or ubuntu kernel v 4.2)  and just showing black screen, but kernel without xen loads normally. > >if in bios disable apic mode Xen boot dom0 but not see any disk (of cource scsi libata and nforce deivers enabled in kernel by "Y") and keyboard does not work. >logs on screen that i can see: >genirq: flags mismatch irq12 00000080 (i8042) vs 00000000 (mce) >genirq: flags mismatch irq1 00000080 (i8042) vs 0002cc00 (spinlock0) >genirq: flags mismatch irq1 00000080 (rtc0) vs 0002cc00 (xen-pcpu) >genirq: flags mismatch irq5 00000080 (sata_nv) vs 0002cc00 (callfunction0) > >