Hi, did anybody use Xen's ucode option successfully? I'm trying to update the microcode before dom0 starts, since my dom0 doesn't have the xen microcode driver. I'm using a vanilla 3.12.x kernel from kernel.org and to the best of my knowledge, the xen microcode kernel driver didn't make it upstream yet, i.e., it's only in konrad's tree. So I probably want ucode=-1. The documentation is speaking of a CPU microcode update BLOB. So all I need is to make the microcode BLOB the last module in grub, right? But: BLOB in which format? Well, on my system the microcode exists in two formats: - /lib/firmware/microcode.dat (not sure what the format is, it's definitely not cpio based, as would be needed for ucode=scan) - many single files in /lib/firmware/intel-ucode/ Which line in grub would be correct? I guess it isn't module /lib/firmware/microcode.dat or module /lib/firmware/intel-ucode/<somefile> by any chance? Now the documentation of ucode goes one to talk to about some file called kernel/x86/microcode/GenuineIntel.bin. But it only talks about it in combination with ucode=scan. A wild guess could be, that this file is identical to microcode.dat. Another wild guess could be, that this file is something I have to download from intel, and this is also the file I have to use as a module in case I'm using ucode=-1 instead of ucode=-1. So could somebody who did all the research and experimenting show his working configuration to me? I think I tried microcode.dat once, and it didn't seem to work. I haven't tried a file from /lib/firmware/intel-ucode/ as I only have one production system and my test system is a VM where microcode updates are not possible. Regards, Sven