I have been doing a lot of testing with UEFI-native booting to Linux recently, and while the results have been quite positive, I have discovered a couple of issues that are preventing Fedora 10 from being fully UEFI compatible. The first issue is with the bootloader: GRUB will fail if memory cannot be allocated at address 1MB. It is not required by UEFI that this address be made available to the OS, and as such GRUB should be able to respond appropriately if 1MB is not available. The second issue is far more pressing, and much more difficult to solve. The linux kernel will behave incorrectly if more than 400k of runtime memory is declared by system firmware. The kernel attempts to map all UEFI runtime memory into the kernel fixmap table, and any requests to map more than 400k are silently ignored. If this memory is accessed later in the boot process (after transition to virtual mode), the kernel will panic. It is my understanding that this mechanism was designed to enable kexec functionality, but this mechanism is UEFI non-compliant. If Fedora is ever to be reliably booted on UEFI systems, this issue must be addressed. I've briefly contacted the LKML, but after very little discussion the issue was forgotten. I personally don't know how to solve the runtime boot problem while still enabling kexec, but it was my hope that if the Fedora community were involved a solution might be found. - Jonathan Barkelew BIOS Engineer American Megatrends